Intraoperative range of motion (ROM) radiographs are routinely taken during scaphoidectomy and four corner fusion surgery (S4CF) at our institution. It is not known if intraoperative ROM predicts postoperative ROM. We hypothesize that patients with a greater intra-operativeROM would have an improved postoperative ROM at one year, but that this arc would be less than that achieved intra- operatively. We retrospectively reviewed 56 patients that had undergone S4CF at our institution in the past 10 years. Patients less than 18, those who underwent the procedure for reasons other than arthritis, those less than one year from surgery, and those that had since undergone wrist arthrodesis were excluded. Intraoperative ROM was measured from fluoroscopic images taken in flexion and extension at the time of surgery. Patients that met criteria were then invited to take part in a virtual assessment and their ROM was measured using a goniometer. T-tests were used to measure differences between intraoperative and postoperative ROM, Pearson Correlation was used to measure associations, and linear regression was conducted to assess whether intraoperative ROM predicts postoperative ROM. Nineteen patients, two of whom had bilateral surgery, agreed to participate. Mean age was 54 and 14 were male and 5 were male. In the majority, surgical indication was scapholunate advanced collapse; however, two of the participants had scaphoid nonunion advanced collapse. No difference was observed between intraoperative and postoperative flexion. On average there was an increase of seven degrees of extension and 12° arc of motion postoperatively with p values reaching significance Correlation between intr-operative and postoperative ROM did not reach statistical significance for flexion, extension, or arc of motion. There were no statistically significant correlations between intraoperative and postoperative ROM. Intraoperative ROM radiographs are not useful at predicting postoperative ROM. Postoperative extension and arc of motion did increase from that measured intraoperatively

Aims. It has been well documented in the arthroplasty literature that lumbar degenerative disc disease (DDD) contributes to abnormal spinopelvic motion. However, the relationship between the severity or pattern of hip osteoarthritis (OA) as measured on an anteroposterior (AP) pelvic view and spinopelvic biomechanics has not been well investigated. Therefore, the aim of the study is to examine the association between the severity and pattern of hip OA and spinopelvic motion. Methods. A retrospective chart review was conducted to identify patients undergoing primary total hip arthroplasty (THA). Plain AP pelvic radiographs were reviewed to document the morphological characteristic of osteoarthritic hips. Lateral spine-pelvis-hip sitting and standing plain radiographs were used to measure sacral slope (SS) and pelvic femoral angle (PFA) in each position. Lumbar disc spaces were measured to determine the presence of DDD. The difference between sitting and standing SS and PFA were calculated to quantify spinopelvic motion (ΔSS) and hip motion (ΔPFA), respectively. Univariate analysis and Pearson correlation were used to identify morphological hip characteristics associated with changes in spinopelvic motion. Results. In total, 139 patients were included. Increased spinopelvic motion was observed in patients with loss of femoral head contour, cam deformity, and acetabular bone loss (all p < 0.05). Loss of hip motion was observed in patients with loss of femoral head contour, cam deformity, and acetabular bone loss (all p < 0.001). A decreased joint space was associated with a decreased ΔPFA (p = 0.040). The presence of disc space narrowing, disc space narrowing > two levels, and disc narrowing involving the L5–S1 segment were associated with decreased spinopelvic motion (all p < 0.05). Conclusion. Preoperative hip OA as assessed on an AP pelvic radiograph predicts spinopelvic motion. These data suggest that specific hip osteoarthritic morphological characteristics listed above alter spinopelvic motion to a greater extent than others. Cite this article: Bone Joint J 2023;105-B(5):496–503

The function of the shoulder joint has traditionally been evaluated based on range of motion (ROM) in predefined anatomical planes and also by using functional scores, which assessed shoulder function based on the ability to conduct certain activities of daily living (ADLs). However, measuring ROM only in terms of flexion-extension, abduction-adduction and internal-external rotation may under-account for the 3-dimensional mobility of the shoulder joint. Furthermore, functional scores, such as the Oxford shoulder score or American shoulder and elbow surgeons (ASES) score, are subjective measures and are not an accurate assessment of shoulder joint function. In this study, we proposed the use of the globe model of the shoulder joint which can be used to provide an objective measure of the global ROM and also function of the shoulder joint – termed the Global and Functional arc of motion (GAM and FAM). Thirty-three young, healthy male patients (23.7 ± 1.5 years) were recruited and tasked to perform eight ADLs and a full humeral circumduction movement which represented their active global ROM. Reflective markers were placed in accordance to the International Society of Biomechanics (ISB) and optical-based motion capture cameras were used to track relative motion of the dominant humerus with respect to the thorax (i.e. thoracohumeral motion). The GAM and FAM were generated by plotting the thoracohumeral on a spherical coordinate system during global ROM and the eight ADLs respectively. Shoulder joint global ROM and function were quantified by calculating the area enclosed by the closed loop of GAM and FAM respectively. The spherical coordinate system, or more commonly referred to as the globe model, describes thoracohumeral movement using plane of elevation (POE), angle of elevation (AOE) and rotation. In our model, POE and AOE represents longitude and latitude of the globe respectively, and rotation is depicted using a red-green-blue (RGB) colour scale. Overall, subject's GAM of the shoulder joint covered an area of 4.64 ± 0.48 units2 compared to only 1.12 ± 0.26 units2 for the FAM. Subjects only required 24.4 ± 5.7 % of their global shoulder ROM for basic daily functioning. Studies that reduced shoulder joint movement into planar movements (i.e. sagittal, coronal and rotation) do not account for the 3-dimensional nature of the joint and doing so may overestimate the requirement of the shoulder joint for ADLs relative to its ROM in each plane. While others have attempted to use the globe model, such studies tend to reduce the globe into its descriptive angles (i.e. POE, AOE and rotation), reducing its intuitiveness. In contrast, by keeping an intact globe, the proposed globe model was more intuitive and yet capable of quantifying both shoulder joint global ROM and function. Doing so, we found that young healthy subjects only required approximately a quarter of their global ROM of the shoulder joint to complete the most common daily tasks, which was significantly less than what was previously reported

Background:. Few clinical hip score include toe-reach motion after THA (put-on-socks, nail-cutting). Some reports have shown whether THA patients can put on socks or not in daily activity, and not shown how they can do it. The purpose of this study is to investigate real pattern of put-on-socks motion in daily activities after THA, and to evaluate safe range of motion for prevention of hip dislocation. Materials and Methods:. Reviewing clinical chart, we investigated highly frequent pattern in wearing socks motion that would cause hip dislocation in ADL in 100 patients with normal lower extremities except for hip joint more than one year after THA, then, we classified the motion pattern. Using an optical 3-D motion analysis (MAC3D system, Motion Analysis, USA), we measured necessary angle of the hip in 10 THA subjects (mean age at operation 61 years old) one year postoperatively, while the patients make such frequent patterns of movement as above. Simultaneously, individual 3-dimensional skeletal model was reconstructed from CT data and implant CAD data. Driving 3-D skeletal model combined with motion analysis data on display (Zed Hip, LEXI), we calculated angle from posture that hip flexion angle was maximum during wearing-socks motion to impingement point (implant and/or bone) for each direction. ALL joint angle was defined as “zero” in supine position. Results:. Resulting from clinical chart, high incident pattern of the motion was “Leg raising pattern” (26%), and “Trunk flexion pattern” (23%) (Figure 1). For above two pattern of the socks-wearing motion, 3-D motion analysis showed that maximum hip flexion angle was 85 ± 13 degrees for leg raising pattern, 88 ± 14 degrees for trunk flexion pattern. Hip angle of abduction/adduction or external/internal rotation was within mean 15 degrees during each motion. 3-D model simulation combined with motion data showed that 39 ± 15 degrees, 33 ± 9.7 degrees for direction of hip flection, 34 ± 17 degrees, 32 ± 11 degrees for direction of hip adduction and 78 ± 21 degrees, 51 ± 21 degrees for direction of hip internal rotation from posture on maximum hip flexion angle to impingement point for each motion, respectively. All cases showed safe range of more than 20 degrees for all direction and impingement occurred between cup and stem in all cases (Figure 2, 3). Discussion:. Recently, there have been trend to decrease limitation of motion in ADL after THA. Safe range of motion without impingement have been enlarged resulting from development of implant design, proper alignment and operative technique. This study showed safe range without impingement in frequent socks-wearing pattern in daily living among THA patients one year after surgery. More research for motion in ADL can lead to remove postoperative restrictions in THA patients

For many years, marker-based systems have been used for motion analysis. However, the emergence of new technologies, such as 4D scanners provide exciting new opportunities for motion analysis. In 4D scanners, the subjects are measured as a dense mesh, which enables the use of shape analysis techniques. In this talk, we will explore how the combination of the rising new motion analysis methods and shape modelling may change the way we think about movement and its analysis

Assessing the efficacy of cervical orthoses in restricting spinal motion has historically proved challenging due to a poor understanding of spinal kinematics and the difficulty in accurately measuring spinal motion. This study is the first to use an 8 camera optoelectronic, passive marker, motion analysis system with a novel marker protocol to compare the effectiveness of the Aspen, Aspen Vista, Philadelphia, Miami-J and Miami-J Advanced collars. Restriction of cervical spine motion was assessed for physiological and functional range of motion (ROM). Nineteen healthy volunteers (12 female, 7 male) were fitted with collars by an approved physiotherapist. ProReflex (Qualisys, Sweden) infra-red cameras were used to track the movement of retro-reflective marker clusters attached to the head and trunk. 3-D kinematic data was collected from uncollared and collared subjects during forward flexion, extension, lateral bending and axial rotation for physiological ROM and during five activities of daily living (ADLs). ROM in the three clinical planes was analysed using the Qualisys Track Manager (Qualisys, Sweden) 6 Degree of Freedom calculation to determine head orientation relative to the trunk. For physiological ROM, the Aspen and Philadelphia were more effective at restricting flexion/extension than the Vista (p<0.001), Miami-J (p<0.001 and p<0.01) and Miami-J Advanced (p<0.01 and p<0.05). The Aspen was more effective at restricting rotation compared to the Vista (p<0.001) and Miami-J (p<0.05). The Vista was least effective at restricting lateral bending (p<0.001). Through functional ROM, the Vista was less effective than the Aspen (p<0.001) and other collars (p<0.01) at restricting flexion/extension. The Aspen and Miami-J Advanced were more effective at restricting rotation than the Vista (p<0.01 and p<0.05) and Miami-J (p<0.05). All the collars were comparable when restricting lateral bending. The Aspen is superior to, and the Aspen Vista inferior to, the other collars at restricting cervical spine motion through physiological ROM. Functional ROM observed during ADLs are less than those observed through physiological ROM. The Aspen Vista is inferior to the other collars at restricting motion through functional ROM. The Aspen collar again performs well, particularly at restricting rotation, but is otherwise comparable to the other collars at restricting motion through functional ranges

Introduction. Today, there is no clear consensus as to the amplitude of movement of the “normal hip”. Knowing the necessary joint mobility for everyday life is important to understand different pathologies and to better plan their treatments. Moreover, determining the hip range of motion (ROM) is one of the key points of its clinical examination. Unfortunately this process may lack precision because of movement of other joints around the pelvis. Our goal was to perform a preliminary study based on the coupling of MRI and optical motion capture to define precisely the necessary hip joint mobility for everyday tasks and to assess the accuracy of the hip ROM clinical exam. Methods. MRI was carried out on 4 healthy volunteers (mean age, 28 years). A morphological analysis was performed to assess any bony abnormalities. Two motion capture sessions were conducted: one aimed at recording routine activities (stand-to-sit, lie down, lace the shoes while seated, pick an object on the floor while seated or standing) known to be painful or prone to implant failures. During the second session, a hip clinical exam was performed successively by 2 orthopedists (2 and 12 years' experience), while the motion of the subjects was simultaneously recorded (Fig.1). These sequences were captured: 1) supine: maximal flexion, maximal IR/ER with hip flexed 90°, maximal abduction; 2) seated: maximal IR/ER with hip and knee flexed 90°. A hand held goniometer was used by clinicians to measure hip angles in those different positions. Hip joint kinematics was computed from the markers trajectories using a validated optimized fitting algorithm which accounted for skin motion artifacts (accuracy: translational error≍0.5 mm, rotational error <3°). The resulting computed motions were applied to patient-specific hip joint 3D models reconstructed from their MRI data (Fig. 2). Hip angles were determined at each point of the motion thanks to two bone coordinate systems (pelvis and femur). The orthopedist's results were compared. Results. All subject's hips were morphologically normal. For all movements, a minimum of 95° hip flexion was required (mean range 95°–107°), lacing the shoes and lying down being the more demanding. Abduction/adduction and IR/ER remained low (± 20°) and variable across subjects. Regarding the clinical exam, the error made by the clinicians varied in the range of ± 10°, except for the flexion and abduction where the error was higher (flexion: mean 9.5°, range −7°–22°; abduction: mean 19.5°, range: 8–32°). No significant differences between the errors made by the two examiners were noted (mean error for each examiner: 7.4° vs. 8.4°). Conclusion. Daily activities of a “normal hip” involve intensive hip flexion, which could explain why such motion can yield hip pain or possible implant failure. This information should be considered in the surgical planning and prosthesis design when restoring patient mobility and stability. The clinical exam seems to be a precise method for determining hip passive motion, if extra care is taken to stabilize the pelvis during flexion and abduction to prevent overestimation of the ROM. Further studies including more subjects are required before attesting the accuracy of this test

Body motion tracking for kinematic study is typically done with optical sensors. The user wears markers and the cameras track them to compute the transformation of the motion frame by frame. This method requires a set up of multiple motion capturing cameras and it can only be done within the specific area. The goal of this project is to create a tracking unit that does not require expensive overhead and can be done in any location. The advancement in micro-machined microelectromechanical system (MEMS) sensors such as accelerometer, gyroscope and magnetometers can be used for human motion tracking. The unit is attached to a body segment or an external housing unit such as a knee brace. The orientation of the unit can be calculated based on the data from all 3 of the sensors. A complementary filter is used to fuse the data together to generate a single Euler angle matrix. Relative motion between the joint can be calculated from the output of 2 of the measuring units. The sensors are calibrated with an average static orientation error of +/−0.7 degree and standard deviation of 1.8 degrees. The dynamic orientation error of rotating around a single axis is 2.38, 0.15 and 0.517 degrees with standard deviation of 0.99, 0.98 and 0.7 degree for roll, pitch and yaw respectively. The initial design shows good result for human body motion tracking. The performance of the unit can be further improved with optimizing the filter and using the data from different type of the sensors to compensate each other

Study Purpose. A preliminary study to compare continuous sagittal plane lumbar inter-vertebral kinematics in 10 healthy volunteers in recumbent and weight bearing configurations using quantitative fluoroscopy. Background. There are no direct in-vivo comparisons between continuous weight bearing and non-weight bearing inter-vertebral kinematics in the same healthy individuals. This information will advance our knowledge of spine mechanics and provide reference values for clinical studies. Methods. Ten male healthy control volunteer subjects aged between 30 and 50 underwent a recumbent bending procedure during fluoroscopy. All participants repeated this in weight bearing. Trunk motion was controlled for range and velocity. Digital image sequences (DICOM) of these movements were captured at 15 fps and analysed using automated frame to frame image registration codes in MATLAB (Mathworks). Inter-vertebral motion characteristics, including inter-vertebral angular range of rotation and attainment rate (Laxity), were calculated. Results. These results are the preliminary output of an ongoing study to create a reference database for normal spine kinematics. Comparisons of the motion patterns within and between participants will be demonstrated along with preliminary statistical analysis of range of motion and speed of attainment (laxity) of the angular range within the first 10° of trunk motion after the inter-vertebral motion starts. Laxity is proposed as a new in vivo proxy for the neutral zone where force is replaced by trunk motion near the neutral position. Conclusion. These preliminary comparisons demonstrate the feasibility of establishing a reference database of lumbar spine kinematics to which patient populations can be compared, potentially allowing these to emerge as outcome measures. No conflicts of interest. Sources of funding: PhD studentship: School of Design Engineering and Computing, Bournemouth University. This abstract has not been previously published in whole or substantial part nor has it been presented previously at a national meeting

Aims. Few reports compare the contribution of the talonavicular articulation to overall range of movement in the sagittal plane after total ankle arthroplasty (TAA) and tibiotalar arthrodesis. The purpose of this study was to assess changes in ROM and functional outcomes following tibiotalar arthrodesis and TAA. Patients and Methods. Patients who underwent isolated tibiotalar arthrodesis or TAA with greater than two-year follow-up were enrolled in the study. Overall arc of movement and talonavicular movement in the sagittal plane were assessed with weight-bearing lateral maximum dorsiflexion and plantarflexion radiographs. All patients completed Short Form-12 version 2.0 questionnaires, visual analogue scale for pain (VAS) scores, and the Foot and Ankle Ability Measure (FAAM). Results. In all, 41 patients who underwent TAA and 27 patients who underwent tibiotalar arthrodesis were enrolled in the study. The mean total arc of movement was 34.2° (17.0° to 59.1°) with an average contribution from the talonavicular joint of 10.5° (1.2° to 28.8°) in the TAA cohort. The average total arc of movement was 24.3° (6.9° to 44.3°) with a mean contribution from the talonavicular joint of 22.8° (5.6° to 41.4°) in the arthrodesis cohort. A statistically significant difference was detected for both total sagittal plane movement (p = 0.00025), and for talonavicular motion (p < 0.0001). A statistically significant lower VAS score (p = 0.0096) and higher FAAM (p = 0.01, p = 0.019, respectively) was also detected in the TAA group. Conclusion. TAA preserves more anatomical movement, has better pain relief and better patient-perceived post-operative function compared with patients undergoing fusion. The relative increase of talonavicular movement in fusion patients may play a role in the outcomes compared with TAA and may predispose these patients to degenerative changes over time. Take home message: TAA preserves more anatomic sagittal plane motion and provides greater pain relief and better patient-perceived outcomes compared with ankle arthrodesis. Cite this article: Bone Joint J 2016;98-B:634–40

As the field of hip arthroscopy continues to develop, functional measures and testing become increasingly important in patient selection, managing patient expectations prior to surgery, and physical readiness for return to athletic participation. The Hip Sport Test (HST) was developed to assess strength, coordination, agility, and range of motion prior to and following hip arthroscopy as a functional assessment. However, the relationship between HST and hip strength, range of motion, and hip-specific patient reported outcome (PRO) measures have not been investigated. The purpose of this study was to evaluate the correlation between the HST scores and measurements of hip strength and range of motion prior to undergoing hip arthroscopy. Between September 2009 and January 2017, patients aged 18-40 who underwent primary hip arthroscopy for the treatment of femoroacetabular impingement with available pre-operative HST, dynamometry, range of motion, and functional scores (mHHS, WOMAC, HOS-SSS) were identified. Patients were excluded if they were 40 years old, had a Tegner activity score < 7, or did not have HST and dynamometry evaluations within one week of each other. Muscle strength scores were compared between affected and unaffected side to establish a percent difference with a positive score indicating a weaker affected limb and a negative score indicating a stronger affected limb. Correlations were made between HST and strength testing, range of motion, and PROs. A total of 350 patients met inclusion criteria. The average age was 26.9 ± 6.5 years, with 34% females and 36% professional athletes. Total and component HST scores were significantly associated with measure of strength most strongly for flexion (rs = −0.20, p < 0 .001), extension (rs = −0.24, p<.001) and external rotation (rs = −0.20, p < 0 .001). Lateral and diagonal agility, components of HST, were also significantly associated with muscle strength imbalances between internal rotation versus external rotation (rs = −0.18, p=0.01) and flexion versus extension (rs = 0.12, p=0.03). In terms of range of motion, a significant correlation was detected between HST and internal rotation (rs = −0.19, p < 0 .001). Both the total and component HST scores were positively correlated with pre-operative mHHS, WOMAC, and HOS-SSS (p<.001 for all rs). The Hip Sport Test correlates with strength, range of motion, and PROs in the preoperative setting of hip arthroscopy. This test alone and in combination with other diagnostic examinations can provide valuable information about initial hip function and patient prognosis

Aims. In computer simulations, the shape of the range of motion (ROM) of a stem with a cylindrical neck design will be a perfect cone. However, many modern stems have rectangular/oval-shaped necks. We hypothesized that the rectangular/oval stem neck will affect the shape of the ROM and the prosthetic impingement. Methods. Total hip arthroplasty (THA) motion while standing and sitting was simulated using a MATLAB model (one stem with a cylindrical neck and one stem with a rectangular neck). The primary predictor was the geometry of the neck (cylindrical vs rectangular) and the main outcome was the shape of ROM based on the prosthetic impingement between the neck and the liner. The secondary outcome was the difference in the ROM provided by each neck geometry and the effect of the pelvic tilt on this ROM. Multiple regression was used to analyze the data. Results. The stem with a rectangular neck has increased internal and external rotation with a quatrefoil cross-section compared to a cone in a cylindrical neck. Modification of the cup orientation and pelvic tilt affected the direction of projection of the cone or quatrefoil shape. The mean increase in internal rotation with a rectangular neck was 3.4° (0° to 7.9°; p < 0.001); for external rotation, it was 2.8° (0.5° to 7.8°; p < 0.001). Conclusion. Our study shows the importance of attention to femoral implant design for the assessment of prosthetic impingement. Any universal mathematical model or computer simulation that ignores each stem’s unique neck geometry will provide inaccurate predictions of prosthetic impingement. Cite this article: Bone Joint Res 2021;10(12):780–789

To determine the biomechanical effect of increasing scaphoid malunion and scaphoid non-union on carpal kinematics during dynamic wrist motion using an active wrist motion simulator. Seven cadaveric upper extremities underwent active wrist flexion and extension in a custom motion wrist simulator with scaphoid kinematics being captured with respect to the distal radius. A three-stage protocol of progressive simulated malunion severity was performed (intact, 10° malunion, 20° malunion) with data analyzed from 45° wrist flexion to 45° wrist extension. Scaphoid malunions were modelled by creating successive volar wedge osteotomies and fixating the resultant scaphoid fragments with 0.062 Kirshner wires. At the completion of malunion motion trials, a scaphoid non-union trial was carried out by removing surgical fixation to observe motion differences from the malunion trials. Motion of the scaphoid, lunate, capitate, and trapezium-trapezoid was recorded and analyzed using active optical trackers. Increasing scaphoid malunion severity did not significantly affect scaphoid or trapezium-trapezoid motion (p>0.05); however, it did significantly alter lunate motion (p<0.001). Increasing malunion severity resulted in progressive lunate extension across wrist motion (Intact – Mal 10: mean dif. = 7.1° ± 1.6, p<0.05; Intact – Mal 20: mean dif. = 10.2° ± 2.0, p<0.05;) although this change was not as great as the difference seen during non-union trials (native – non-union: mean dif. = 13.8° ± 3.7, p<0.05). In this in-vitro model, increasing scaphoid malunion severity was associated with progressive extension of the lunate in all wrist positions. The clinical significance of this motion change is yet to be elucidated, but this model serves as a basis for understanding the kinematic consequences of scaphoid malunion deformities

Introduction. Sheffield Children's Hospital specialises in limb lengthening for children. Soft tissue contracture and loss of range of motion at the knee and ankle are common complications. This review aims to look at therapeutic techniques used by the therapy team to manage these issues. Materials & Methods. A retrospective case review of therapy notes was performed of femoral and tibial lengthening's over the last 3 years. Included were children having long bone lengthening with an iIntramedullary nail, circular frame or mono-lateral rail. Patients excluded were any external fixators crossing the knee/ankle joints. Results. 20 tibial and 25 femoral lengthening's met the inclusion criteria. Pathologies included, complex fractures, limb deficiency, post septic necrosis and other congenital conditions leading to growth disturbance. All patients had issues with loss of motion at some point during the lengthening process. The knee and foot/ankle were equally affected. Numerous risk factors were identified across the cohort. Treatment provided included splinting, serial casting, bolt on shoes, exercise therapy, electrical muscle stimulation and passive stretching. Conclusions. Loss of motion in lower limb joints was common. Patients at higher risk were those with abnormal anatomy, larger target lengthening's, poor compliance or lack of access to local services. Therapy played a significant role in managing joint motion during treatment. However, limitations were noted. No one treatment option gave preferential outcomes, selection of treatment needed to be patient specific. Future research should look at guidelines to aid timely input and avoid secondary complications

Study purpose and background. Kinematic variables have been identified as potential biomarkers for low back pain patients; however, an in-depth comparison between chronic (n=22), acute (n=15), and healthy controls (n=136) has not been done. This retrospective data analysis compared intervertebral lumbar motion parameters, angular range of motion, translation, maximum disc height, motion share inequality (MSI) and variability (MSV), and laxity, between these groups. Methods and results. Kinematic parameters were determined using video tracking techniques utilising quantitative fluoroscopy (QF), during both weight-bearing and recumbent controlled sagittal bending tasks. Data was analysed for normality, and appropriate statistical tests were applied to determine differences between groups. There were no significant differences between the groups for age, height, weight and sex. Whilst few differences were found between acute and healthy groups, differences were shown between both chronic and healthy, and acute and chronic groups for all six parameters. Of particular note were examples of differences in the motion share parameters between the acute and chronic populations, with an increased MSI in the chronic group during recumbent flexion, and MSV during recumbent extension, and inversely an increase in MSV in the acute group during weight-bearing flexion. Conclusion. Analysis of intervertebral lumbar motion provides valuable insights into kinematic differences between chronic, acute, and healthy control populations. These findings suggest that there is variation between the groups which is knowledge that may benefit management strategies. Further exploration of the time varying data is warranted to explore how such differences may relate to the motion share inequalities and variability shown. Conflicts of Interest. No conflicts of interest. Sources of Funding. No funding obtained

Range of Motion (ROM) assessments are routinely used during joint replacement to evaluate joint stability before, during and after surgery to ensure the effective restoration of patient biomechanics. This study aimed to quantify axial torque in the femur during ROM assessment in total hip arthroplasty to define performance criteria against which hip instruments can be verified. Longer term, this information may provide the ability to quantitatively assess joint stability, extending to quantitation of bone preparation and quality. Joint loads measured with strain-gaged instruments in five cadaveric femurs prepared using posterior approach were analysed. Variables such as surgeon-evaluator, trial offset and specimen leg and weight were used to define 13 individual setups and paired with surgeon appraisal of joint tension for each setup. Peak torque loads were then identified for specific motions within the ROM assessment. The largest torque measured in most setups was observed during maximum extension and external rotation of the joint, with a peak torque of 13Nm recorded in a specimen weighing 98kg. The largest torque range (19.4Nm) was also recorded in this specimen. Other motions within the trial reduction showed clear peaks in applied torque but with lower magnitude. Relationships between peak torque, torque range and specimen weight produced an R2 value greater than 0.65. The data indicated that key influencers of torsional loads during ROM were patient weight, joint tension and limb motion. This correlation with patient weight should be further investigated and highlights the need for population representation during cadaveric evaluation. Although this study considered a small sample size, consistent patterns were seen across several users and specimens. Follow-up studies should aim to increase the number of surgeon-evaluators and further vary specimen size and weight. Consideration should also be given to alternative surgical approaches such as the Direct Anterior Approach

Aims. We aimed to assess the reliability and validity of OpenPose, a posture estimation algorithm, for measurement of knee range of motion after total knee arthroplasty (TKA), in comparison to radiography and goniometry. Methods. In this prospective observational study, we analyzed 35 primary TKAs (24 patients) for knee osteoarthritis. We measured the knee angles in flexion and extension using OpenPose, radiography, and goniometry. We assessed the test-retest reliability of each method using intraclass correlation coefficient (1,1). We evaluated the ability to estimate other measurement values from the OpenPose value using linear regression analysis. We used intraclass correlation coefficients (2,1) and Bland–Altman analyses to evaluate the agreement and error between radiography and the other measurements. Results. OpenPose had excellent test-retest reliability (intraclass correlation coefficient (1,1) = 1.000). The R. 2. of all regression models indicated large correlations (0.747 to 0.927). In the flexion position, the intraclass correlation coefficients (2,1) of OpenPose indicated excellent agreement (0.953) with radiography. In the extension position, the intraclass correlation coefficients (2,1) indicated good agreement of OpenPose and radiography (0.815) and moderate agreement of goniometry with radiography (0.593). OpenPose had no systematic error in the flexion position, and a 2.3° fixed error in the extension position, compared to radiography. Conclusion. OpenPose is a reliable and valid tool for measuring flexion and extension positions after TKA. It has better accuracy than goniometry, especially in the extension position. Accurate measurement values can be obtained with low error, high reproducibility, and no contact, independent of the examiner’s skills. Cite this article: Bone Joint Res 2023;12(5):313–320

For clinical movement analysis, optical marker-based motion capture is the gold standard. With the advancement of AI-driven computer vision, markerless motion capture (MMC) has emerged. Validity against the marker-based standard has only been examined for lightly-dressed subjects as required for marker placement. This pilot study investigates how different clothing affects the measurement of typical gait metrics. Gait tests at self-selected speed (4 km/h) were performed on a treadmill (Motek Grail), captured by 9 cameras (Qualisys Miqus, 720p, f=100Hz) and analyzed by a leading MMC application (Theia, Canada). A healthy subject (female, h=164cm, m=54kg) donned clothes between trials starting from lightly dressed (LD: bicycle tight, short-sleeved shirt), adding a short skirt (SS: hip occlusion) or a midi-skirt (MS: partial knee occlusion) or street wear (SW: jeans covering ankle, long-sleeved blouse), the lattern combined with a short jacket (SWJ) or a long coat (SWC). Gait parameters (mean±SD, t=10s) calculated (left leg, mid-stance) were ankle pronation (AP-M), knee flexion (KF-M), pelvic obliquity (PO-M) and trunk lateral lean (TL-M) representing clinically common metrics, different joints and anatomic planes. Four repetitions of the base style (LD) were compared to states of increased garment coverage using the t-test (Bonferroni correction). For most gait metrics, differences between the light dress (LD) and various clothing styles were absent (p>0.0175), small (< 2SD) or below the minimal clinically important differences (MCID). For instance, KF-M was for LD=10.5°±1.7 versus MD=12.0°±0.5 (p=0.07) despite partial knee cover. AP-M measured for LD=5.2°±0.6 versus SW=4.1°±0.7 (p<0.01) despite ankle cover-up. The difference for KF-M between LD=10.5°±1.7 versus SWL=6.0°±0.9, SW and SWJ (7.6°±1.5, p<0.01) indicates more intra-subject gait variability than clothing effect. This study suggests that typical clothings styles only have a small clinically possibly negligible effect on common gait parameters measured with MMC. Thus, patients may not need to change clothes or be instructed to wear specific garments. In addition to avoiding marker placement, this further increases speed, ease and economy of clinical gait analysis with MMC facilitating high volume or routine application

Aims. This study aimed to compare the outcomes of two different postoperative management approaches following surgical fixation of ankle fractures: traditional cast immobilization versus the Early Motion and Directed Exercise (EMADE) programme. Methods. A total of 157 patients aged 18 years or older who underwent successful open reduction and internal fixation (ORIF) of Weber B (AO44B) ankle fractures were recruited to this randomized controlled trial. At two weeks post-surgical fixation, participants were randomized to either light-weight cast-immobilization or the EMADE programme, consisting of progressive home exercises and weekly advice and education. Both groups were restricted to non-weightbearing until six weeks post-surgery. The primary outcome was assessed using the Olerud-Molander Ankle Score (OMAS) questionnaire at 12 weeks post-surgery, with secondary measures at two, six, 24, and 52 weeks. Exploratory cost-effectiveness analyses were also performed. Results. Overall, 130 participants returned their 12-week OMAS questionnaires. The mean OMAS was significantly higher in the EMADE group compared with the immobilized group (62.0 (SD 20.9) vs 48.8 (SD 22.5)), with a clinically meaningful mean difference of 13.2 (95% CI 5.66 to 20.73; p < 0.001). These differences were maintained at week 24, with convergence by week 52. No intervention-related adverse events, including instability, were reported. Conclusion. The EMADE programme demonstrated an accelerated recovery compared to traditional six-week cast immobilization for those who have undergone ORIF surgery to stabilize Weber B (AO44B) ankle fractures. The study found the EMADE intervention to be safe. Cite this article: Bone Joint J 2024;106-B(9):949–956

Nearly one quarter of ankle fractures have a recognized syndesmosis injury. An intact syndesmosis ligament complex stabilizes the distal tibio-fibular joint while allowing small, physiologic amounts of relative motion. When injured, malreduction of the syndesmosis has been found to be the most important independent factor that contributes to inferior functional outcomes. Despite this, significant variability in surgical treatment remains. This may be due to a poor understanding of normal dynamic syndesmosis motion and the resultant impact of static and dynamic fixation on post-injury syndesmosis kinematics. As the syndesmosis is a dynamic structure, conventional CT static images do not provide a complete picture of syndesmosis position, giving potentially misleading results. Dynamic CT technology has the ability to image joints in real time, as they are moved through a range-of-motion (ROM). The aim of this study was to determine if syndesmosis position changes significantly throughout ankle range of motion, thus warranting further investigation with dynamic CT. This is an a priori planned subgroup analysis of a larger multicentre randomized clinical trial, in which patients with AO-OTA 44-C injuries were randomized to either Tightrope or screw fixation. Bilateral ankle CT scans were performed at 1 year post-injury, while patients moved from maximal dorsiflexion (DF) to maximal plantar flexion (PF). In the uninjured ankles, three measurements were taken at one cm proximal to the ankle joint line in maximal DF and maximal PF: Anterior (ASD), middle (MSD), and posterior (PSD) syndesmosis distance, in order to determine normal syndesmosis position. Paired samples t-tests compared measurements taken at maximal DF and maximal PF. Twelve patients (eight male, six female) were included, with a mean age of 44 years (±13years). The mean maximal DF achieved was 1-degree (± 7-degrees), whereas the mean maximal PF was 47-degrees (± 8-degrees). The ASD in DF was 3.0mm (± 1.1mm) versus 1.9mm (± 0.8mm) in PF (p<0.01). The MSD in DF was 3.3mm (±1.1mm) versus 2.3mm (±0.9mm) in PF (p<0.01). The PSD in DF was 5.3mm (±1.5mm) versus 4.6mm (±1.9mm) in PF (p<0.01). These values are consistent with the range of normal parameters previously reported in the literature, however this is the first study to report the ankle position at which these measurements are acquired and that there is a significant change in syndesmosis measurements based on ankle position. Normal syndesmosis position changes in uninjured ankles significantly throughout range of motion. This motion may contribute to the variation in normal anatomy previously reported and controversies surrounding quantifying anatomic reduction after injury, as the ankle position is not routinely standardized, but rather static measurements are taken at patient-selected ankle positions. Dynamic CT is a promising modality to quantify normal ankle kinematics, in order to better understand normal syndesmosis motion. This information will help optimize assessment of reduction methods and potentially improve patient outcomes. Future directions include side-to-side comparison using dynamic CT analysis in healthy volunteers

Purpose and Background. Work-related musculoskeletal disorders (WRMSD) can affect 56–80% of physiotherapists. Patient handling is reported as a significant risk factor for developing WRMSD with the back most frequently injured. Physiotherapists perform therapeutic handling to manually assist and facilitate patients’ movement to aid rehabilitation, which can increase physiotherapists risk of experiencing high forces during patient handling. Methods and Results. A descriptive cross-sectional study was completed to explore and quantitatively measure the movement of ten physiotherapists during patient handling, over one working day, in a neurological setting. A wearable 3-dimensional motion analysis system, Xsens (Movella, Henderson, NV), was used to measure physiotherapist movement and postures in the ward setting during patient treatment sessions. The resulting joint angles were reported descriptively and compared against a frequently used ergonomic assessment tool, the Rapid Upper Limb Assessment (RULA). Physiotherapists adopted four main positions during patient handling tasks: 1) kneeling; 2) half-kneeling; 3) standing; and 4) sitting. Eight patient handling tasks were identified and described: 1) Lie-to-sit; 2) sit-to-lie; 3) sit-to-stand; facilitation of 4) upper limb; 5) lower limb; 6) trunk; and 7) standing treatments; and 8) walking facilitation. Kneeling and sitting positions demonstrated greater neck extension and greater lumbosacral flexion during treatments which scores highly with the RULA. Conclusion. This research identified that patient treatment tasks were more often performed in kneeling or sitting positions than standing. Current moving and handling guidance teaches moving and handling in a standing position; loading and stresses experienced by the physiotherapists may differ in sitting or kneeling positions. Conflicts of interest. None. Sources of funding. None. This work has been presented as a poster at the CSP conference Glasgow 2023

Introduction. Interactions between hip, pelvis and spine, as abnormal spinopelvic movements, have been associated with inferior outcomes following total hip arthroplasty (THA). Changes in pelvis position lead to a mutual change in functional cup orientation, with both pelvic tilt and rotation having a significant effect on version. Hip osteoarthritis (OA) patients have shown reduced hip kinematics which may place increased demands on the pelvis and the spine. Sagittal and coronal planes assessments are commonly done as these can be adequately studied with anteroposterior and lateral radiographs. However, abnormal pelvis rotation is likely to compromise the outcome as they have a detrimental effect on cup orientation and increased impingement risk. This study aims to determine the association between dynamic motion and radiographic sagittal assessments; and examine the association between axial and sagittal spinal and pelvic kinematics between hip OA patients and healthy controls (CTRL). Methods. This is a prospective study, IRB approved. Twenty hip OA pre-THA patients (11F/9M, 67±9 years) and six CTRL (3F/3M, 46±18 years) underwent lateral spinopelvic radiographs in standing and seated bend-and-reach (SBR) positions. Pelvic tilt (PT), pelvic-femoral-angle (PFA) and lumbar lordosis (LL) angles were measured in both positions and the differences (Δ) between standing and SBR were calculated. Dynamic SBR and seated maximal-trunk-rotation (STR) were recorded in the biomechanics laboratory using a 10-infrared camera and processed on a motion capture system (Vicon, UK). Direct kinematics extracted maximal pelvic tilt (PT. max. ), hip flexion (HF. max. ) and (mid-thoracic to lumbar) spinal flexion (SF. max. ). The SBR pelvic movement contribution (ΔPT. rel. ) was calculated as ΔPT/(ΔPT+ΔPFA)∗100 for the radiographic analysis and as PT. max. /(PT. max. +HF. max. ) for the motion analyses. Axial and sagittal, pelvic and spinal range of motion (ROM) were calculated for STR and SBR, respectively. Spearman's rank-order determined correlations between the spinopelvic radiographs and sagittal kinematics, and the sagittal/axial kinematics. Mann-Whitney U-tests compared measures between groups. Results. Radiograph readings correlated with sagittal kinematics during SBR for ΔPT and PT. max. (ρ=0.64, p<0.001), ΔPFA and HF. max. (ρ=0.44, p<0.0002), and ΔLL and SF. max. (ρ=0.34, p=0.002). Relative pelvic movements (ΔPT. rel. ) were not different between radiographic (11%±21) and biomechanical (15%±29) readings (p=0.9). Sagittal SRB spinal flexion correlated with the axial STR rotation (ρ=0.43, p<0.0001). Although not seen in CTRL, sagittal SRB pelvic flexion strongly correlated with STR pelvic rotation in OA patients (ρ=0.40, p=0.002). All spinopelvic parameters were different between the patients with OA and CTRL. CTRLs exhibited significantly greater mobility and less variability in all 3 segments (spine, pelvis, hip) and both planes (axial and sagittal) (Table 1). Conclusion. Correlation between sagittal kinematics and radiographical measurements during SBR validates the spinopelvic mobility assessments in the biomechanics laboratory. Axial kinematics of both pelvis and spine correlated significantly in OA patients, suggesting that patients with abnormal sagittal mobility are likely to also exhibit abnormal axial mobility, which can further potentiate any at-risk kinematics. Significantly lower OA ROM must be investigated post-THA. Pre-THA variability of both sagittal and axial movements indicates that both planes must be considered ahead of surgical planning with navigation and/or robotics. For any figures or tables, please contact the authors directly

Abstract. Objectives. Neonatal motor development transitions from initially spontaneous to later increasingly complex voluntary movements. A delay in transitioning may indicate cerebral palsy (CP). The general movement optimality score (GMOS) evaluates infant movement variety and is used to diagnose CP, but depends on specialized physiotherapists, is time-consuming, and is subject to inter-observer differences. We hypothesised that an objective means of quantifying movements in young infants using motion tracking data may provide a more consistent early diagnosis of CP and reduce the burden on healthcare systems. This study assessed lower limb kinematic and muscle force variances during neonatal infant kicking movements, and determined that movement variances were associated with GMOS scores, and therefore CP. Methods. Electromagnetic motion tracking data (Polhemus) was collected from neonatal infants performing kicking movements (min 50° knee extension-flexion, <2 seconds) in the supine position over 7 minutes. Tracking data from lower limb anatomical landmarks (midfoot inferior, lateral malleolus, lateral knee epicondyle, ASIS, sacrum) were applied to subject-scaled musculoskeletal models (Gait2354_simbody, OpenSim). Inverse kinematics and static optimisation were applied to estimate lower limb kinematics (knee flexion, hip flexion, hip adduction) and muscle forces (quadriceps femoris, biceps femoris) for isolated kicks. Functional principal component analysis (fPCA) was carried out to reduce kicking kinematic and muscle force waveforms to PC scores capturing ‘modes’ of variance. GMOS scores (lower scores = reduced variety of movement) were collected in parallel with motion capture by a trained operator and specialised physiotherapist. Pearson's correlations were performed to assess if the standard deviation (SD) of kinematic and muscle force waveform PC scores, representing the intra-subject variance of movement or muscle activation, were associated with the GMOS scores. Results. The study compared GMOS scores, kinematics, and muscle force variances from a total of 26 infants with a mean corrected gestational age of 39.7 (±3.34) weeks and GMOS scores between 21 and 40. There was a significant association between the SD of the PC scores for knee flexion and the GMOS scores (PC1: R = 0.59, p = 0.002; PC2: R = 0.49, p = 0.011; PC3: R = 0.56, p = 0.003). The three PCs captured variances of the overall flexion magnitude (66% variance explained), early-to-late kick knee extension (20%), and continual to biphasic kicking (6%). For hip flexion, only the SD of PC1 correlated with GMOS scores (PC1: R = 0.52, p = 0.0068), which captured the variance of the overall flexion magnitude (81%). For the biceps femoris, the SD of PC1 and PC3 associated with GMOS scores (PC1: R = 0.50, p = 0.002; PC3: R = 0.45, p = 0.03), which captured the variance of the overall bicep force magnitude (79%) and early-to-late kick bicep activation (8%). Conclusions. Infants with reduced motor development as scored in the GMOS displayed reduced variances of knee and hip flexion and biceps femoris activation across kicking cycles. These findings suggest that combining objectively measured movement variances with existing classification methods could facilitate the development of more consistent and accurate diagnostic tools for early detection of CP. Declaration of Interest. (b) declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported:I declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project

Abstract. Objectives. Impingement in total hip replacements (THRs), including bone-on-bone impingement, can lead to complications such as dislocation and loosening. The aim of this study was to investigate how the location of the anterior inferior iliac spine (AIIS) affected the range of motion before impingement. Methods. A cohort of 25 CT scans (50 hips) were assessed and nine hips were selected with a range of AIIS locations relative to the hip joint centre. The selected CT Scans were converted to solid models (ScanIP) and THR components (DePuy Synthes) were virtually implanted (Solidworks). Flexion angles of 100⁰, 110⁰, and 120⁰ were applied to the femur, each followed by internal rotation to the point of impingement. The lateral, superior and anterior extent of the AIIS from the Centre of Rotation (CoR) of the hip was measured and its effect on the range of motion was recorded. Results. There was found to be a significant (p<0.05) inverse relationship between the ROM of the THR and the lateral measure of the AIIS. Of the three measures, the lateral AIIS measure showed the strongest relationship with ROM to impingement (R=0.73) with the anterior and superior measures resulting in R values of 0.41 and 0.56 respectively. For every millimetre lateral the AIIS location, there was typically a loss of 1.2° of range of motion. With increasing lateralisation, the AIIS was positioned more directly over the femur, thereby reducing the ROM in the THR during high flexion positions. No soft tissue was included in the models which would have affected the ROM. Conclusions. The results from this study have shown that the lateral measure of the AIIS could be a predictor for bone-on-bone impingement. To build confidence, wider study of AIIS location variation is needed, as well as analysis under impingement prone activities of daily living. Declaration of Interest. (b) declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported:I declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project

Abstract. Objectives. Hip joint laxity after total hip arthroplasty (THA) has been considered to cause microseparation and lead to complications, including wear and dislocation. In the native hip, the hip capsular ligaments may tighten at the limits of range of hip motion and provide a passive stabilising force preventing edge loading and reduce the risk of dislocation. Previous attempts to characterise mechanical properties of hip capsular ligaments have been largely variable and there are no cadaveric studies quantifying the force contributions of each ligament in different hip positions. In this study we quantify the passive force contribution of the hip capsular ligaments throughout a complete range of motion (ROM). Methods. Nine human cadaveric hip specimens (6 males and 3 females) with mean age of (76.4 ± 9.0 years) were skeletonised, preserving the capsular ligaments. Prepared specimens were tested in a 6 degree of freedom system to assess ROM with 5 Nm torque applied in external and internal rotation throughout hip flexion and extension. Capsular ligaments were resected in a stepwise fashion to assess internal force contributions of the iliofemoral (superior and inferior), pubofemoral, and ischiofemoral ligaments during ROM. Results. In external rotation, the superior and inferior iliofemoral ligament minimum force contributions were (136.52 ± 27.15 N) in flexion and (82.40 ± 27.85 N) in extension, respectively. In internal rotation, the ischiofemoral ligament force contributions were dominant in adducted-flexion positions and abducted-extension positions. Conclusions. These findings provide insights into the primary capsular structures that stabilise the hip joint in different manoeuvres. This data allows for an improved understanding of which capsular ligaments contribute the most to hip stability and has important implications for choosing surgical approaches and repair strategies to minimise complications related to joint instability. Declaration of Interest. (b) declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported:I declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project

Introduction. In knee biomechanics the concept of the envelope of motion (EOM) has proven to be a powerful method to characterize joint mechanics and the effect of surgical interventions. It is furthermore indispensable for numerical model validation. While commonly used for tibiofemoral kinematics, there is very little report of applying the concept to patellofemoral kinematics. EOM measurements require precise and reproducible displacement and load control in all degrees of freedom (DOF), which robotic testing has proven to provide. The objectives of this study were therefore to (1) develop a robotic method to assess patellofemoral EOM as a function of tibiofemoral EOM, (2) compare resulting patellofemoral kinematics to published data, and (3) determine which DOFs in the tibiofemoral EOM mostly account for the patellofemoral EOM. Material and Methods. The developed robotic (KUKA KR140 comp) method was evaluated using 8 post-mortem human leg specimens of both genders (age: 55±11 years, BMI: 23±5). Firstly, tibiofemoral neutral flexion was established as well as the EOM by applying anterior-posterior (±100 N), medial-lateral (±100 N), internal-external (±4 Nm) and varus-valgus (±12 Nm) loads under low compression (44 N) at 7 flexion angles. Secondly, patellofemoral flexion kinematics and EOM were measured during a robotic playback of the previously established tibiofemoral kinematics. During these measurements, the quadriceps tendon was loaded with a hanging weight (20 kg) via a pulley system directing the force to the anterior superior iliac spine. Kinematics were tracked optically (OptiTrack) and registered to CT scans using co-scanned aluminum cylinders and beads embedded in the patella. The overall patellofemoral EOM was calculated as the extent of patellar motion observed during manipulating the tibia inside the tibiofemoral EOM in all DOFs. Additionally, patellofemoral EOMs were calculated for tibial manipulations along individual DOFs to analyze the importance of these DOFs. Results. Trends and magnitudes of patella shift, tilt and rotation during knee flexion were similar to reported in-vivo measurements. Envelopes of patellar shift and tilt during internal-external tibiofemoral rotation closely resembled those reported for in-vitro results despite methodological differences. Tibiofemoral internal-external and varus-valgus rotation had the largest effect on patellofemoral EOM. EOMs in patellar shift and tilt were dominated by internal-external rotation in early flexion and varus-valgus rotation in late flexion. The EOM in patellar rotation was dominated by tibiofemoral varus-valgus rotation throughout flexion. Manipulating the tibia in a combined internal-external and varus-valgus rotation envelope yielded the same patellofemoral EOM as the overall patellofemoral EOM. Conclusion. This study has established a novel robotic method to assess the patellofemoral envelope of motion as a function of tibiofemoral EOM. Resulting patellofemoral kinematics resembled data reported in literature. It was furthermore shown that is sufficient to establish a combined internal-external and varus-valgus envelope of tibiofemoral motion as bases of the patellofemoral EOM, as including the anterior-posterior and medial-lateral tibiofemoral envelopes yielded no additional effect

Aims. Total knee arthroplasty (TKA) may provoke ankle symptoms. The aim of this study was to validate the impact of the preoperative mechanical tibiofemoral angle (mTFA), the talar tilt (TT) on ankle symptoms after TKA, and assess changes in the range of motion (ROM) of the subtalar joint, foot posture, and ankle laxity. Methods. Patients who underwent TKA from September 2020 to September 2021 were prospectively included. Inclusion criteria were primary end-stage osteoarthritis (Kellgren-Lawrence stage IV) of the knee. Exclusion criteria were missed follow-up visit, post-traumatic pathologies of the foot, and neurological disorders. Radiological angles measured included the mTFA, hindfoot alignment view angle, and TT. The Foot Function Index (FFI) score was assessed. Gait analyses were conducted to measure mediolateral changes of the gait line and ankle laxity was tested using an ankle arthrometer. All parameters were acquired one week pre- and three months postoperatively. Results. A total of 69 patients (varus n = 45; valgus n = 24) underwent TKA and completed the postoperative follow-up visit. Of these, 16 patients (23.2%) reported the onset or progression of ankle symptoms. Varus patients with increased ankle symptoms after TKA had a significantly higher pre- and postoperative TT. Valgus patients with ankle symptoms after TKA showed a pathologically lateralized gait line which could not be corrected through TKA. Patients who reported increased ankle pain neither had a decreased ROM of the subtalar joint nor increased ankle laxity following TKA. The preoperative mTFA did not correlate with the postoperative FFI (r = 0.037; p = 0.759). Conclusion. Approximately one-quarter of the patients developed ankle pain after TKA. If patients complain about ankle symptoms after TKA, standing radiographs of the ankle and a gait analysis could help in detecting a malaligned TT or a pathological gait. Cite this article: Bone Joint J 2023;105-B(11):1159–1167

Introduction/Aim. Mid-flexion instability is a well-documented, but often poorly understood cause of failure of TKA. NAVIO robotic-assisted TKA (RA-TKA) offers a novel, integrative approach as a planning, execution as well as an evaluation tool in TKA surgery. RA-TKA provides a hybrid planning technique of measured resection and gap balancing- generating a predictive soft-tissue balance model, prior to making cuts. Concurrently, the system uses a semi-active robot to facilitate both the execution and verification of the plan, as it pertains to both the static and dynamic anatomy. The goal of this study was to assess the ability of the NAVIO RA-TKA to plan, execute and deliver an individualized approach to the soft-tissue balance of the knee, specifically in the “mid-flexion” arc of motion. Materials and Methods. Between May and September 2018, 50 patients underwent NAVIO RA-TKA. Baseline demographics were collected, including age, gender, BMI, and range of motion. The NAVIO imageless technique was used to plan the procedure, including: surface-mapping of the static anatomy; objective assessment of the dynamic, soft-tissue anatomy; and then application of a hybrid of measured-resection and gap-balancing technique. Medial and lateral gaps as predicted by the software were recorded throughout the entire arc of motion at 15° increments. After executing the plan and placing the components, actual medial and lateral gaps were recorded throughout the arc of motion. Results. In the assessment of coronal-plane balance, the average deviation from the predicted plan between 0–90° was 0.9mm in both the medial and lateral compartments (range 0.5–1.2mm). In the mid-flexion arc (15–75°), final soft-tissue stability was within 1.0mm of the predictive plan (range 0.9–1.2mm). Discussion/Conclusions. In this study, NAVIO RA-TKA demonstrated a highly accurate and reproducible surgical technique to plan, execute and verify a balanced a soft-tissue envelope in TKA. Objective soft-tissue balancing of the TKA can now be performed, including the mid-flexion arc of motion. Further analysis can determine if these objective measurements will translate into improved patient-reported outcome scores

Background. Dynamic measurement of continuous intervertebral motion in low back pain (LBP) research in-vivo is developing. Lumbar motion parameters with the features of biomarkers are emerging and show promise for advancing understanding of personalised biometrics of LBP. However, measurement of changes over time inevitably involve error, due to subjects' natural variation and/or variation in the measurement process. Thus, intra-subject repeatability of parameters to measure changes over time should be established. Methods. Seven lumbar spine motion parameters, measured using quantitative fluoroscopy (QF), were assessed for intra-subject repeatability: Intervertebral range-of-motion (IV-RoM), laxity, motion sharing inequality (MSI), motion sharing variability (MSV), flexion translation and flexion disc height. Intra-subject reliability (ICC) and minimal detectable change (MDC95) of baseline and 6-week follow-up measurements were obtained for 109 healthy volunteers (54 coronal and 55 sagittal). Results. Reliability was substantial to excellent for repeated measurements of IV-RoM, laxity, flexion translation and disc height during recumbent passive motion (ICC:0.69–0.95) and during active weight-bearing motion (ICC:0.64–0.92). MSI was moderate to excellent across both positions (ICC:0.43–0.91). The reliability of MSV was generally poorer for both positions (0.14–0.65). For all parameters, measurement error exceeded 42%. Conclusion. Recumbent IV-RoM, laxity and disc height demonstrated the best repeatability at 6-weeks suggesting they may be better outcome moderators in clinical studies than other variables. However measurement errors for all parameters were higher than the minimal changes of interest. These results are limited to healthy controls and should be regarded as reference values. Similar studies in CNSLBP patients are required. No conflicts of interest. Sources of Funding: Dr Rebecca Hemming received a Seedcorn Bursary from the Cardiff Institute of Tissue Engineering and Repair (CITER) and Professor Alan Breen received a project grant from the European Chiropractors Union Research Fund (ECURF)

The syndesmosis ligament complex stabilizes the distal tibiofibular joint, while allowing for the subtle fibular motion that is essential for ankle congruity. Flexible fixation with anatomic syndesmosis reduction results in substantial improvements in functional outcomes. New dynamic CT technology allows real-time imaging, as the ankle moves through a range of motion. The aim of this study was to determine if dynamic CT analysis is a feasible method for evaluating syndesmosis reduction and motion following static and flexible syndesmosis fixation. This is a subgroup analysis of a larger multicenter randomized clinical trial, in which patients with AO 44-C injuries were randomized to either Tightrope (one knotless Tightrope, Group T) or screw fixation (two 3.5-mm cortical screws, Group S). Surgical techniques and rehabilitation were standardized. Bilateral ankle CT scans were performed at one year post-injury, while patients moved from maximal dorsiflexion (DF) to maximal plantar flexion (PF). Three measurements were taken at one cm proximal to the ankle joint line in maximal DF and maximal PF: anterior, midpoint, and posterior tibiofibular distances. T-tests compared Group T and Group S, and injured and uninjured ankles in each group. Fifteen patients (six Group T [three male], nine Group S [eight male]) were included. There was no difference for mean age (T = 42.8 ± 14.1 years, S = 37 ± 12.6, P = 0.4) or time between injury and CT scan (T = 13 ± 1.8 months, S = 13.2 ± 1.8, P = 0.8). Of note in Group S, seven of nine patients had at least one broken screw and one additional patient had screws removed by the time of their dynamic CT. There was no significant difference between treatment groups for tibiofibular distance measurements in maximal PF or DF. Group T showed no significant difference between the injured and uninjured side for tibiofibular measurements in maximal PF and DF, suggesting anatomic reduction. For Group S, however, there was a significantly larger distance for all three measurements at maximal PF compared to the uninjured ankle (all P < 0 .05). In all but one Group S patient, screws were broken or removed prior to their dynamic CT, allowing possible increased syndesmotic motion, similar to Group T. Despite this, dynamic CT analysis detected increased tibiofibular distance in Group S as ankles moved into maximal PF when compared with the uninjured ankle. Given the importance of anatomic syndesmosis reduction, dynamic ankle CT technology may provide valuable physiologic information warranting further investigation

Aims. Pelvic tilt (PT) can significantly change the functional orientation of the acetabular component and may differ markedly between patients undergoing total hip arthroplasty (THA). Patients with stiff spines who have little change in PT are considered at high risk for instability following THA. Femoral component position also contributes to the limits of impingement-free range of motion (ROM), but has been less studied. Little is known about the impact of combined anteversion on risk of impingement with changing pelvic position. Methods. We used a virtual hip ROM (vROM) tool to investigate whether there is an ideal functional combined anteversion for reduced risk of hip impingement. We collected PT information from functional lateral radiographs (standing and sitting) and a supine CT scan, which was then input into the vROM tool. We developed a novel vROM scoring system, considering both seated flexion and standing extension manoeuvres, to quantify whether hips had limited ROM and then correlated the vROM score to component position. Results. The vast majority of THA planned with standing combined anteversion between 30° to 50° and sitting combined anteversion between 45° to 65° had a vROM score > 99%, while the majority of vROM scores less than 99% were outside of this zone. The range of PT in supine, standing, and sitting positions varied widely between patients. Patients who had little change in PT from standing to sitting positions had decreased hip vROM. Conclusion. It has been shown previously that an individual’s unique spinopelvic alignment influences functional cup anteversion. But functional combined anteversion, which also considers stem position, should be used to identify an ideal THA position for impingement-free ROM. We found a functional combined anteversion zone for THA that may be used moving forward to place total hip components. Cite this article: Bone Jt Open 2021;2(10):834–841

Objectives. Many studies have investigated the kinematics of the lumbar spine and the morphological features of the lumbar discs. However, the segment-dependent immediate changes of the lumbar intervertebral space height during flexion-extension motion are still unclear. This study examined the changes of intervertebral space height during flexion-extension motion of lumbar specimens. Methods. First, we validated the accuracy and repeatability of a custom-made mechanical loading equipment set-up. Eight lumbar specimens underwent CT scanning in flexion, neural, and extension positions by using the equipment set-up. The changes in the disc height and distance between adjacent two pedicle screw entry points (DASEP) of the posterior approach at different lumbar levels (L3/4, L4/5 and L5/S1) were examined on three-dimensional lumbar models, which were reconstructed from the CT images. Results. All the vertebral motion segments (L3/4, L4/5 and L5/S1) had greater changes in disc height and DASEP from neutral to flexion than from neutral to extension. The change in anterior disc height gradually increased from upper to lower levels, from neutral to flexion. The changes in anterior and posterior disc heights were similar at the L4/5 level from neutral to extension, but the changes in anterior disc height were significantly greater than those in posterior disc height at the L3/4 and L5/S1 levels, from neutral to extension. Conclusions. The lumbar motion segment showed level-specific changes in disc height and DASEP. The data may be helpful in understanding the physiologic dynamic characteristics of the lumbar spine and in optimising the parameters of lumbar surgical instruments. Cite this article: M. Fu, Q. Ye, C. Jiang, L. Qian, D. Xu, Y. Wang, P. Sun, J. Ouyang. The segment-dependent changes in lumbar intervertebral space height during flexion-extension motion. Bone Joint Res 2017;6:245–252. DOI: 10.1302/2046-3758.64.BJR-2016-0245.R1

Wrist motion is achieved primarily via rotation at the radiocarpal and midcarpal joints. The contribution of each carpal bone to total range of motion has been previously investigated, although there is no consensus regarding the influence of each structure to global wrist motion. The objective of this comprehensive in-vitro biomechanical study was to determine the kinematics of the capitate, scaphoid and lunate during unconstrained simulated wrist flexion-extension. In addition, this study examined the effect of motion direction (i.e. flexion or extension) on the kinematics and contribution of the carpal bones. Seven fresh frozen cadaveric upper limb specimens (age: 67±18 yrs) were amputated mid-humerus, and the wrist flexors/extensors were exposed and sutured at their musculotendinous junctions. Each specimen was mounted on a wrist motion simulator in neutral forearm rotation with the elbow at 90° flexion. Passive flexion and extension motion of the wrist was simulated by moving a K-wire, inserted into the third metacarpal, through the flexion/extension motion arc at a speed of ∼5 mm/sec under muscle tone loads of 10N. Carpal kinematics were captured using optical tracking of bone fixated markers. Kinematic data was analysed from ±35° flexion/extension. Scaphoid and lunate motion differed between wrist flexion and extension, but correlated linearly (R‸2=0.99,0.97) with capitate motion. In wrist extension, the scaphoid (p=0.03) and lunate (p=0.01) extended 83±19% & 37±18% respectively relative to the capitate. In wrist flexion, the scaphoid (p=1.0) and lunate (p=0.01) flexed 95±20% and 70±12% respectively relative to the capitate. The ratio of carpal rotation to global wrist rotation decreased as the wrist moved from flexion to extension. The lunate rotates on average 46±25% less than the capitate and 35±31% less than the scaphoid during global wrist motion (p=0.01). The scaphoid rotates on average 11±19% less than the capitate during wrist flexion and extension (p=0.07). There was no difference in the contribution of carpal bone motion to global wrist motion during flexion (p=0.26) or extension (p=0.78). The capitate, lunate and scaphoid move synergistically throughout planar motions of the wrist. Our study found that both the scaphoid and lunate contributed at a greater degree during wrist flexion compared to extension, suggesting that the radiocarpal joint plays a more critical role in wrist flexion. Our results agree with previous studies demonstrating that the scaphoid and lunate do not contribute equally to wrist motion and do not function as a single unit during planar wrist motion. The large magnitude of differential rotation observed between the scaphoid and lunate may be responsible for the high incidence of scapholunate ligament injuries relative to other intercarpal ligaments. An understanding of normal carpal kinematics may assist in developing more durable wrist arthroplasty designs

Wrist motion is achieved primarily via rotation at the radiocarpal and midcarpal joints. The contribution of each carpal bone to total range of motion has been previously investigated, although there is no consensus regarding the influence of each structure to global wrist motion. The objective of this comprehensive in-vitro biomechanical study was to determine the kinematics of the capitate, scaphoid and lunate during unconstrained simulated wrist flexion-extension. In addition, this study examined the effect of motion direction (i.e. flexion or extension) on the kinematics and contribution of the carpal bones. Seven fresh frozen cadaveric upper limb specimens (age: 67±18 yrs) were amputated mid-humerus, and the wrist flexors/extensors were exposed and sutured at their musculotendinous junctions. Each specimen was mounted on a wrist motion simulator in neutral forearm rotation with the elbow at 90° flexion. Passive flexion and extension motion of the wrist was simulated by moving a K-wire, inserted into the third metacarpal, through the flexion/extension motion arc at a speed of ∼5 mm/sec under muscle tone loads of 10N. Carpal kinematics were captured using optical tracking of bone fixated markers. Kinematic data was analysed from ±35° flexion/extension. Scaphoid and lunate motion differed between wrist flexion and extension, but correlated linearly (R^2=0.99,0.97) with capitate motion. In wrist extension, the scaphoid (p=0.03) and lunate (p=0.01) extended 83±19% & 37±18% respectively relative to the capitate. In wrist flexion, the scaphoid (p=1.0) and lunate (p=0.01) flexed 95±20% and 70±12% respectively relative to the capitate. The ratio of carpal rotation to global wrist rotation decreased as the wrist moved from flexion to extension. The lunate rotates on average 46±25% less than the capitate and 35±31% less than the scaphoid during global wrist motion (p=0.01). The scaphoid rotates on average 11±19% less than the capitate during wrist flexion and extension (p=0.07). There was no difference in the contribution of carpal bone motion to global wrist motion during flexion (p=0.26) or extension (p=0.78). The capitate, lunate and scaphoid move synergistically throughout planar motions of the wrist. Our study found that both the scaphoid and lunate contributed at a greater degree during wrist flexion compared to extension, suggesting that the radiocarpal joint plays a more critical role in wrist flexion. Our results agree with previous studies demonstrating that the scaphoid and lunate do not contribute equally to wrist motion and do not function as a single unit during planar wrist motion. The large magnitude of differential rotation observed between the scaphoid and lunate may be responsible for the high incidence of scapholunate ligament injuries relative to other intercarpal ligaments. An understanding of normal carpal kinematics may assist in developing more durable wrist arthroplasty designs

The literature indicates that femoroacetabular impingement (FAI) patients do not return to the level of controls (CTRL) following surgery. The purpose of this study was to compare hip biomechanics during stair climbing tasks in FAI patients before and two years after undergoing corrective surgery against healthy controls (CTRL). A total of 27 participants were included in this study. All participants underwent CT imaging at the local hospital, followed by three-dimensional motion analysis done at the human motion biomechanics laboratory at the local university. Participants who presented a cam deformity >50.5° in the oblique-axial or >60° in the radial planes, respectively, and who had a positive impingement test were placed in the FAI group (n=11, age=34.1±7.4 years, BMI=25.4±2.7 kg/m2). The remaining participants had no cam deformity and negative impingement test and were placed in the CTRL group (n=16, age=33.2±6.4 years, BMI=26.3±3.2 kg/m2). The CTRL group completed the biomechanics protocol once, whereas the FAI group completed the protocol twice, once prior to undergoing corrective surgery for the cam FAI, and the second time at approximately two years following surgery. At the human motion biomechanics laboratory, participants were outfitted with 45 retroreflective markers placed according to the UOMAM marker set. Participants completed five trials of stairs task on a three step instrumented stair case to measure ground reaction forces while 10 Vicon MX-13 cameras recorded the marker trajectories. Data was processed using Nexus software and divided into stair ascent and stair descent tasks. The trials were imported into custom written MatLab software to extract peak pelvis and hip kinematics and hip kinetic variables. Non-parametric Kruskal-Wallis tests were used to determine significant (p < 0.05) differences between the groups. No significant differences occurred during the stair descent task between any of the groups. During the stair ascent task, the CTRL group had significantly greater peak hip flexion angle (Pre-Op=58±7.1°, Post-Op=58.1±6.6°, CTRL=64.1±5.1°) and sagittal hip range of motion (ROM) (Pre-Op=56.7±6.7°, Post-Op=56.3±5.5°, CTRL=61.7±4.2°) than both the pre- and post-operative groups. Pre-operatively, the FAI group had significantly less peak hip adduction angle (Pre-Op=2±4.5°, Post-Op=3.4±4.4°, CTRL=5.5±3.7°) and hip frontal ROM (Pre-Op=9.9±3.4°, Post-Op=11.9±5.4°, CTRL=13.4±2.5°) compared to the CTRL group. No significant differences occurred in the kinetic variables. Our findings are in line with the Rylander and colleagues (2013) who also found that hip sagittal ROM did not improve following corrective surgery. Their study included a mix of cam and pincer-type FAI, and had a mean follow-up of approximately one year. Our cohort included only cam FAI and they had a mean follow-up of approximately two years, indicating with the extra year, the patients still did not show sagittal hip kinematics improvement. In the frontal plane, there was no significant difference between the post-op and the CTRL, indicating that the postoperative FAI reached the level of the CTRLs. This is in line with recent work that indicates a more medialized hip contact force vector following surgery, suggesting better hip stabilization

Ideally the hip arthroplasty should not be subject to bony or prosthetic impingement, in order to minimise complications and optimise outcomes. Modern 3d planning permits pre-operative simulation of the movements of the planned hip arthroplasty to check for such impingement. For this to be meaningful, however, it is necessary to know the range of movement (ROM) that should be simulated. Arbitrary “normal” values for hip ROM are of limited value in such simulations: it is well known that hip ROM is individualised for each patient. We have therefore developed a method to determine this individualised ROM using CT scans. CT scans were performed on 14 cadaveric hips, and the images were segmented to create 3d virtual models. Using Matlab software, each virtual hip was moved in all potential directions to the point of bony impingement, thus defining an individualised impingement-free 3d ROM envelope. This was then compared with the actual ROM as directly measured from each cadaver using a high-resolution motion capture system. For each hip, the ROM envelope free of bony impingement could be described from the CT and represented as a 3d shape. As expected, the directly measured ROM from the cadaver study for each hip was smaller than the CT-based prediction, owing to the presence of constraining soft tissues. However, for movements associated with hip dislocation (such as flexion with internal rotation), the cadaver measurements matched the CT prediction, to within 10°. It is possible to determine an individual's range of clinically important hip movements from a CT scan. This method could therefore be used to create truly personalised movement simulation as part of pre-operative 3d surgical planning

Background. New marker free motion analysis systems are being used extensively in the area of sports medicine and physiotherapy. The accuracy and validity of use in an orthopaedic setting have not been fully assessed for these newer marker free motion analysis systems. The aim of this study is to compare leg length and varus/valgus knee measurements performed by leg measurement x-ray, and performed using the new marker free motion analysis system (Organic motion biostage). Methods. Patients attending the orthopaedic department for total knee replacements were recruited. They underwent radiological leg measurement x-ray, clinical leg measurement, and finally assessment using the organic motion biostage system. These were analysed using the motion monitor software, microsoft excel and minitab 16. Results. For 23 patients assessed, all methods showed a statistically significant result (p<0.05) using paired t-tests. This rejects the null hypothesis- indicating that organic motion does not have the accuracy currently to measure leg length or knee varus/valgus angle. Conclusions. Results indicate that the organic motion biostage system- a new marker free motion analysis system, is not feasible currently as a method of accurately measuring leg-length. Given the current modelling methods used by this new system there are limitations, that if addressed may yet allow the system to become a useful clinical tool. These authors feel it still has applications in orthopaedics as a useful, quick, and easy to use method of motion analysis and functional screen in orthopaedic patients, and warrants further investigation. We also present a case of lumbar pedicle subtraction osteotomy, and show how markerless motion analysis is a useful tool for assessing spinal sagittal balance, and its effect on the biomechanics of walking. Level of Evidence. IV

Dual mobility hip arthroplasty utilizes a freely rotating polyethylene liner to protect against dislocation. As liner motion has not been confirmed in vivo, we investigated the liner kinematics in vivo using dynamic radiostereometry. 16 patients with Anatomical Dual Mobility acetabular components were included. Markers were implanted in the liners using a drill guide. Static RSA recordings and patient reported outcome measures were obtained at post-op and 1-year follow-up. Dynamic RSA recordings were obtained at 1-year follow-up during a passive hip movement: abduction/external rotation, adduction/internal rotation (modified FABER-FADIR), to end-range and at 45° hip flexion. Liner- and neck movements were described as anteversion, inclination and rotation. Liner movement during modified FABER-FADIR was detected in 12 of 16 patients. Median (range) absolute liner movements were: anteversion 10° (5–20), inclination 6° (2–12), and rotation 11° (5–48) relative to the cup. Median absolute changes in the resulting liner/neck angle (small articulation) was 28° (12–46) and liner/cup angle (larger articulation) was 6° (4–21). Static RSA showed changes in median (range) liner anteversion from 7° (-12–23) postoperatively to 10° (-3–16) at 1-year follow-up and inclination from 42 (35–66) postoperatively to 59 (46–80) at 1-year follow-up. Liner/neck contact was associated with high initial liner anteversion (p=0.01). The polyethylene liner moves over time. One year after surgery the liner can move with or without liner/neck contact. The majority of movement is in the smaller articulation between head and liner

Purpose. The goal of Total Ankle Arthroplasty (TAA) is to relieve pain and restore healthy function of the intact ankle. Restoring intact ankle kinematics is an important step in restoring normal function to the joint. Previous robotic laxity testing and functional activity simulation showed the intact and implanted motion of the tibia relative to the calcaneus is similar. However there is limited data on the tibiotalar joint in either the intact or implanted state. This current study compares modern anatomically designed TAA to intact tibiotalar motion. Method. A robotic testing system including a 6 DOF load cell (AMTI, Waltham, MA) was used to evaluate a simulated functional activity before and after implantation of a modern anatomically designed TAA (Figure 1). An experienced foot and ankle surgeon performed TAA on five fresh-frozen cadaveric specimens. The specimen tibia and fibula were potted and affixed to the robot arm (KUKA Robotics Inc., Augsburg, Germany) while the calcaneus was secured to a fixed pedestal (Figure 1). Passive reflective motion capture arrays were fixed to the tibia and talus and a portable coordinate measuring machine (Hexagon Metrology Group, Stockholm, Sweden) established the location of the markers relative to anatomical landmarks palpated on the tibia. A four camera motion capture system (The Motion Monitor, Innovative Sports Training, Chicago, IL) recorded the movement of the tibia and talus. The tibia was rotated from 30 degrees plantar flexion to 15 degrees dorsiflexion to simulate motions during the stance phase of gait. At each flexion angle the robot found the orientation which zeroed all forces and torques except compressive force, which was either 44N or 200N. Results. Preliminary data indicates the tibiotalar motion of the TAA is similar to the intact ankle. The pattern and magnitude of tibiotalar translations and rotations are similar between the intact and implanted states for both 44N and 200N compressive loads (Figure 2). The most variation occurs with internal-external rotation. Increased translation especially in the anterior-posterior directions was observed in plantarflexion while the mediolateral translation remained relatively centered moving less than a millimeter. The intact talus with respect to the calcaneus had less than 3 degrees of rotation over the whole arc of ankle flexion (Figure 3). The angular motion of the implanted talus was similar in pattern to the intact talus, however there were offsets in all three angular directions which changed depending on the loading (Figure 3). This indicates that most of the motion that occurs between the intact tibial calcaneal complex occurs in the tibiotalar joint. Conclusion. Although more investigation is required, this study adds to the limited available tibiotalar kinematic data. This current study suggests the anatomical TAA design allows the tibiotalar joint to behave in similar way to the intact tibiotalar joint. Restoring intact kinematics is an important step in restoring normal function to the joint. For figures/tables, please contact authors directly.

Objectives. Loss of motion following spine segment fusion results in increased strain in the adjacent motion segments. However, to date, studies on the biomechanics of the cervical spine have not assessed the role of coupled motions in the lumbar spine. Accordingly, we investigated the biomechanics of the cervical spine following cervical fusion and lumbar fusion during simulated whiplash using a whole-human finite element (FE) model to simulate coupled motions of the spine. Methods. A previously validated FE model of the human body in the driver-occupant position was used to investigate cervical hyperextension injury. The cervical spine was subjected to simulated whiplash exposure in accordance with Euro NCAP (the European New Car Assessment Programme) testing using the whole human FE model. The coupled motions between the cervical spine and lumbar spine were assessed by evaluating the biomechanical effects of simulated cervical fusion and lumbar fusion. Results. Peak anterior longitudinal ligament (ALL) strain ranged from 0.106 to 0.382 in a normal spine, and from 0.116 to 0.399 in a fused cervical spine. Strain increased from cranial to caudal levels. The mean strain increase in the motion segment immediately adjacent to the site of fusion from C2-C3 through C5-C6 was 26.1% and 50.8% following single- and two-level cervical fusion, respectively (p = 0.03, unpaired two-way t-test). Peak cervical strains following various lumbar-fusion procedures were 1.0% less than those seen in a healthy spine (p = 0.61, two-way ANOVA). Conclusion. Cervical arthrodesis increases peak ALL strain in the adjacent motion segments. C3-4 experiences greater changes in strain than C6-7. Lumbar fusion did not have a significant effect on cervical spine strain. Cite this article: H. Huang, R. W. Nightingale, A. B. C. Dang. Biomechanics of coupled motion in the cervical spine during simulated whiplash in patients with pre-existing cervical or lumbar spinal fusion: A Finite Element Study. Bone Joint Res 2018;7:28–35. DOI: 10.1302/2046-3758.71.BJR-2017-0100.R1

Abstract. Introduction. Persistent medial laxity increases the risk of failure for ACL reconstruction. To address this, multiple reconstruction techniques have been created. To date, no single strand reconstruction constructs have been able to restore both valgus and rotational stability. In response to this, a novel single strand Short Isometric Construct (SIC) MCL reconstruction was developed. Methods. Eight fresh-frozen cadaveric specimens were tested in three states: 1) intact 2) after sMCL and dMCL transection, and 3) after SIC MCL reconstruction. In each state, four loading conditions were applied at varying flexion angles: 90N anterior drawer, 5Nm tibial external rotation torque, 8Nm valgus torque, and combined 90N anterior drawer plus 5Nm tibial external rotation torque. Results. Transection of the sMCL and dMCL resulted in increased laxity with external rotation torque, valgus torque, and combined anterior drawer plus external rotation. SIC MCL reconstruction restored external rotation and valgus stability to intact levels throughout all degrees of flexion. In the combined test SIC MCL reconstruction also restored stability to intact levels for both anterior distraction and external rotation throughout the range of motion. No significant differences were noted between intact and SIC reconstruction. Conclusion. The single-limb short isometric construct (SIC) MCL reconstruction restored native valgus and rotatory stability to a sMCL- and dMCL-deficient knee in biomechanical testing

Purpose and Background. Physical mechanisms underlying back pain impairment are poorly understood. Measuring movement features linked to back pain should help understand its causes and decide on best management. Previous kinematic studies have pointed to diverse features distinguishing back pain sufferers. However, the complexity of 3D kinematics means that it is difficult to choose, a priori, which variables or variable combinations are most important. This study set out to obtain a rich set of kinematic data from spinal regions and lower extremities during typical movement tasks, and analyse all of these variables simultaneously to obtain globally important distinguishing features. To this end, a novel distance metric between pairs of motion sequences was used to construct distance matrices. Analyses were carried out directly on these distance matrices. Methods and Results. 20 controls (age: 28 ± 7.6, 10 female) and 20 chronic LBP subjects (age: 41 ± 10.7, 4 female) were recruited. Kinematic data were obtained whilst subjects stood from sitting (‘STS’), picking up (‘Picking’) and lowering (‘Lowering’) a 5kg box, and walking (right (‘WalkRight’) and left sides (‘WalkLeft’)). For each task, permutation tests for group differences were carried out, based on the pseudo-F statistic calculated from the distance matrices. A similar approach was used to identify local differences at time points and joints. Group mean motion sequences were compared using a custom OpenSim model. Significant differences were obtained for STS (pseudo-F=2.8, p=0.017), WalkRight (pseudo-F=3.27, p=0.008) and WalkLeft (pseudo-F=3.39, p=0.005). Conclusion. Comparisons of movement tasks between groups revealed significant differences for STS and walking. Visualisation of group mean motion sequences, and local analyses assisted in the detailed understanding of these differences. This provides a visually intuitive means of studying complex motion differences between groups, without prior assumptions regarding which variables are important. No conflicts of interest. No funding. Original study funded by Arthritis Research UK MRC (Medical Research Council) Centre for Musculoskeletal Health and Work

Background. Ankle fractures are extremely common but unfortunately, over 20% fail to obtain good to excellent recovery. For those requiring surgical fixation, usual-care post-surgery has included six-weeks cast immobilisation and non-weightbearing. Disuse atrophy and joint stiffness are detrimental sequelae of this management. While rehabilitation, starting at two-weeks post-surgery is viewed as safe, the literature contains methodological flaws and a lack of focus on early exercise, perpetuating the controversy over the effectiveness of early exercise interventions. Objectives. Our objectives were to determine if following operative fixation for Weber B fracture, the physiotherapy intervention, early motion and directed exercise (EMADE), applied in the clinical setting, were superior to Usual-care at 12-weeks (primary outcome) and 24-weeks. Design and Methods. We undertook a pragmatic-RCT, recruiting 157 surgically fixed Weber B ankle fracture patients, to establish if EMADE was superior to the Usual-care of 6-weeks immobilisation. The EMADE physiotherapy intervention (between week-2 and 4 post-surgery) utilised a removable cast and combined non-weightbearing progressive home exercises with manual therapy, advice and education. The primary outcome measure was the OMAS at 12-weeks. Results. 130 participants returned their 12-weeks post-surgery data, exceeding the 60/group threshold set by the a-priory power calculation. Group OMAS means were; 62.0 and 48.8 (SD 21, 22.5) EMADE, Usual-care respectively, yielding a clinically meaningful mean difference of 13.2 on the OMAS and a statistical difference (95% CI p< 0.001, 5.66 to 20.73). Both clinically meaningful and statistically significant findings were maintained at week-24. There were no intervention related or unexpected adverse events, including instability. Conclusions. This clinic set pragmatic-RCT yielded both clinical and statistical outcomes at week-12 in favour of the EMADE physiotherapy intervention over the Usual-care of 6-weeks immobilisation, in surgically fixed Weber B ankle fracture patients. These positive findings were maintained at week-24 and justify EMADE physiotherapy as a viable treatment option

There are a variety of sizes currently available for reverse total shoulder arthroplasty (RTSA) implant systems. Common sizing options include a smaller 36 to 38 mm or a larger 40 to 42 mm glenosphere, and are typically selected based on surgeon preference or patient size. Previous studies have only evaluated the abduction and adduction range of motion within a single plane of elevation, providing a limited view of the joint's possible range of motion. The purpose of this study was to use computer modeling to evaluate the abduction and adduction range of motion across multiple planes of elevation for a range of glenosphere sizes. Computed tomography images of four cadaveric specimens (age: 54 ± 24 years) were used to obtain the osseous anatomy to be utilised in the model. Solid-body motion studies of the RTSA models were constructed with varying glenosphere diameters of 33, 36, 39, 42, and 45 mm in Solidworks (Dassault Systems, US). The implant components were scaled, while maintaining a consistent centre of rotation. Simulations encompassing the full range of abduction and adduction were conducted for the planes of elevation between −15˚ and 135˚ at 15˚ intervals, with the motion of the humerus being constrained in neutral internal-external rotation throughout all planes. Angles of elevation were obtained utilising the humeral long axis and the RTSA centre of rotation. Statistical analysis was performed using repeated measures ANOVA. Glenosphere diameter was found to significantly affect the adduction range of motion (p=0.043), in which the largest size provided approximately 17˚ more adduction range of motion than the smallest. However, abduction range of motion was not found to be significantly affected through the alteration of glenosphere size (p=0.449). The plane of elevation was not found to significantly affect abduction or abduction (p=0.585 & p=0.225, respectively). Increasing glenosphere diameter resulted in an increased adduction range of motion when averaged across the tested planes of elevation; however the observed influence on abduction was not significant. These are similar to the trends observed in the previous single plane of elevation studies. These findings illustrate the importance of implant sizing related to range of motion. Further studies are required to determine the influence of glenosphere size on internal and external range of motion

Shoulder arthroplasty, both primary (TSA) and reverse (RTSA), are common interventions for arthritis and cuff tear arthropathy. The effect of shoulder arthroplasty on shoulder motion is of particular interest in assessing the effectiveness of the procedure and the development and biomechanical testing of implants. A comparison of the arthroplasty shoulder to that of the non-operated contralateral shoulder provides insight into how well the reconstruction has restored natural shoulder motion. The purpose of this study was to ascertain the shoulder motion of patients who have undergone shoulder arthroplasty and to compare the motion of the reconstructed and contralateral natural sides. Eleven human subjects (70±9yrs) who had undergone total shoulder arthroplasty wore a custom instrumented shirt for the waking hours of one day. The 3D orientation of each humeral sensor was transformed with respect to the torso to allow for the calculation of humeral elevation and plane of elevation angles. Joint angles for each subject were then discretised, and the operative and contralateral normal (control) shoulders were then compared. The majority of both the arthroplasty and control shoulder elevation motions took place below 80° of elevation, totaling on average 1910±373 and 1887±312 motions per hour, respectively. Conversely, elevations greater than 80° were significantly less with occurrences totaling only 55±31 and 78±41 motions per hour for the arthroplasty and control shoulders, respectively (p<0.01). Both the arthroplasty and control shoulder were at elevations below 80° for 88±7% and 87±7% of the day, respectively. When the total motion of the arthroplasty and non-operative control shoulders were compared, no statistically significant difference was detected (p=0.8), although the non-operated side exhibited marginally more motion than the operated side, an effect which was larger at higher elevation angles (p=0.3). This study provides insight into the effects of shoulder arthroplasty on thoraco-humeral motion and compares it to the non-operative side. Interestingly, there were no significant differences measured between the arthroplasty and the control side, which may demonstrate the effectiveness of reconstruction on restoring natural shoulder motion. It is interesting to note that on average, each shoulder arthroplasty elevated above 80° approximately 55 times per hour, corresponding to just under 330,000 motions per year. Similarly, when elevations greater than 60° are extrapolated, the resulting yearly motions total approximately 1.5 million cycles (Mc), which suggests that the ‘duty cycle’ of the shoulder is similar to the hip, approximated to be between 1–2 Mc per year. Arthroplasty wear simulators should be calibrated to simulate these patterns of motion, and component design may be improved by understanding the kinematics of actual shoulder motion

Purpose and Background:. Healthy adults with a curvy (lordotic) lumbar spine were shown to lift a load from the floor by stooping, while straight (flat) spines squatted. Since skin-surface motion capture often misrepresents internal curvature this study calculated internal lumbar curvature during lifting in the same cohort and compared lumbosacral motion. Methods:. Magnetic resonance imaging (MRI) was performed in standing and bending forward to 30, 45 and 60°, with markers on the skin at L1, L3, L5 and S1. Lumbar spine shape was characterised using statistical shape modelling and participants grouped into ‘curvy’ and ‘straight’ spine sub-groups (N=8). On a separate day participants lifted a box (6–15 kg) from the floor without instruction while Vicon cameras tracked sagittal movement of L1, L3 and L5 skin markers. Sacral angle (to horizontal) was calculated from pelvic markers. Matching markers during MRI and lifting sessions allowed vertebral centroid positions (L1, L3, L5, S1) during lifting to be calculated using custom MATLAB code. Results:. The curvy group had more internal lumbar lordosis at pick up despite stooping to lift the load. From upright standing motion occurred earlier at the upper lumbar levels (L1–L3) compared with lower lumbar (L3–L5). During lifting straight spines had greater rigid-body motion of the entire lumbar spine compared with curvy spines who demonstrated more varied intersegmental motion with greater sacral flexion. Conclusion:. Individuals with very lordotic spines retained some degree of internal lordosis despite stooping when lifting. The lumbar spine appears more mobile at the upper levels, L1–L3, and constrained motion was seen in those with the least lordosis

Abstract. Introduction. Historic MCL reconstruction techniques focused on the superficial MCL to restore valgus stability while overlooking tibial external rotation and the deep MCL. This study assessed the ability of a contemporary medial collateral ligament (MCL) reconstruction and a deep MCL (dMCL) reconstruction to restore rotational and valgus knee stability. Methods. Six pairs fresh-frozen cadaveric knee specimens with intact soft tissue were tested in four states: 1) intact 2) after sMCL and dMCL sectioning, 3) contemporary MCL reconstruction (LaPrade et al), and 4) dMCL reconstruction. In each state, four loading conditions were applied at varying flexion angles: 8Nm valgus torque, 5Nm tibial external rotation torque, 90N anterior drawer, and combined 90N anterior drawer plus 5Nm tibial external rotation torque. Results. Transection of the sMCL and dMCL resulted in increased laxity with valgus torque, external rotation torque, and combined anterior drawer plus external rotation. dMCL reconstruction restored external rotation stability to intact levels throughout all degrees of flexion but did not restore valgus stability at any flexion angle. Contemporary MCL reconstruction restored valgus and external rotation stability at 0° and 20° and valgus stability at 40°. In the combined anterior drawer plus tibial external rotation trial, the dMCL restored stability at 20° and improved stability between 40° and 90° flexion. Conversely, the contemporary MCL reconstruction did not restore stability at any degree of flexion. Conclusion. Deep MCL reconstruction restored rotational stability to the knee throughout range of motion but not valgus stability. The contemporary MCL reconstruction restored stability only near full extension

Abstract

Purpose. To achieve 3D kinematic analysis of total knee arthroplasty (TKA), 2D/3D registration techniques, which use X-ray fluoroscopic images and computer aided design model of the knee implants, have been applied to clinical cases. However, most conventional methods have needed time-consuming and labor-intensive manual operations in some process. In particular, for the 3D pose estimation of tibial component model from X-ray images, these manual operations were carefully performed because the pose estimation of symmetrical tibial component get severe local minima rather than that of unsymmetrical femoral component. In this study, therefore, we propose an automated 3D kinematic estimation method of tibial component based on statistical motion model, which is created from previous analyzed 3D kinematic data of TKA. Methods. The used 2D/3D registration technique is based on a robust feature-based (contour-based) algorithm. In our proposed method, a statistical motion model which represents average and variability of joint motion is incorporated into the robust feature-based algorithm, particularly for the pose estimation of tibial component. The statistical motion model is created from previous a lot of analyzed 3D kinematic data of TKA. In this study, a statistical motion model for relative knee motion of the tibial component with respect to the femoral component was created and utilized. Fig. 1 shows each relative knee motion model for six degree of freedom (three translations and three rotations parameter). Thus, after the pose estimation of the femoral component model, 3D pose of the tibial component model is determined by maximum a posteriori (MAP) estimation using the new cost function introduced the statistical motion model. Experimental results. To validate the feasibility and effectiveness of 3D pose estimation for the tibial component using the proposed method, experiments using X-ray fluoroscopic images of 20 TKA patients under the squatting knee motion were performed. For the creation of correct pose (reference data) and the statistical motion model, we used the 3D pose data which were got by carefully applying previous method to the contour images which spurious edges and noises were removed manually. In order to ensure the validity for the statistical motion model of the proposed method, leave-one-out cross validation method was applied. In the 3D pose estimation of tibial component model, for the only first frame, initial guess pose of the model was manually given. For all images except for the first frame, the 3D pose of the model was automatically estimated without manual initial guess pose of the model. To assess the automation performance, the automation rate was calculated, and the rate was defined as the X-ray frame number of satisfying clinical required accuracy (error within 1mm, 1 degree) relative to all X-ray frame number. As results of the experiments, 3D pose of the tibial component model for all X-ray images except for the first frame was full-automatically stably-estimated, and the automation rate was 80.1 %. Conclusions. The proposed method by MAP estimation introduced the statistical motion model was successfully performed, and did not need labor-intensive manual operations for 3D pose estimation of tibial component. For any figures or tables, please contact authors directly (see Info & Metrics tab above).

INTRODUCTION:. As a consequence from cervical arthroplasty, spine structural stiffness, loading and kinematics are changed, resulting in issues like adjacent segment degeneration and altered range of motion. However, complex anatomical structures and lack of adequate precision to study the facet joint (FJ) segmental motion in 3D have prevented proper quantitative analyses. In the current study, we investigate the innovative use of a local coordinate system on the surface of the superior articular process of the caudal vertebral body in order to analyze FJ segmental motion using CT-based 3D vertebral models in flexion/extension. METHODS:. CT images were obtained from six patients (2F/4M, mean age: 53 y.o.) with cervical degenerative disc disease in neutral, flexion and extension positions. CT data was used to create subject-specific surface mesh models of each vertebral body. From these, mean normal vectors were calculated for all FJ surfaces and posterior walls from C3/4 down to C6/7 (Fig. 1). The global coordinate system (x, y, z) corresponds to the CT scanner. Within this system, a new local coordinate system (u, v, w) was set on the centroid of each FJ surface (Fig. 1), where the u-, v-, and w- axes correspond to the normal-to-the-FJ, right-left and cranio-caudal directions, respectively. In flexion/extension, translations in mm were calculated as differences in the FJ centroid position and rotations were calculated in degrees as angular differences of the vector of the opposing surface in flexion/extension. Results are presented as mean ± SD. Differences within vertebral levels and left/right FJs were sought using 1- or 2-way ANOVA, respectively. RESULTS:. The flexion/extension segmental motion was described in its six degrees-of-freedom. Among the three translations, the largest movement was observed in the cranio-caudal direction (u = −0.22 ± 0.47 mm, v = 0.11 ± 0.89 mm, w = −2.06 ± 1.60 mm); while the three rotations about the (u, v, w) axes showed a dominant rotation about the v-axis (u = −0.41 ± 4.42°, v = −5.12 ± 5.61°, w = −0.01 ± 2.71°). Comparing translational and rotational motions by cervical level, movements at C6/7 were shown to be smaller than those at the other levels (p < 0.05) (Figs. 2, 3). There were no significant differences in the movement of the FJ between left and right sides (p > 0.05). DISCUSSION:. A key finding of this study was that along with the expected translation in the w-axis, there was rotation about the v-axis consistent with the overall neck flexion-to-extension motion. If the rotation about the v-axes were negligible, the FJ motion could be considered as a pure translation (sliding), but the data suggests otherwise. This finding supports the hypothesis of a rolling-sliding type of facet segmental motion that might be influenced by the facet surface curvature. Future studies will focus on analyses of the changes in FJ gap with motion and characterization of the facet surfaces' curvature and congruence. SIGNIFICANCE: An innovative look into flexion/extension motion from the FJ point of view describes FJ segmental motion as a sliding-rolling motion instead of the traditional concept of sliding-only mechanism

Introduction. Hip resurfacing arthroplasty has been surgical options in younger and more active patients with osteoarthritis (OA) and osteonecrosis (ON) of the femoral head. Although excellent midterm results of this procedure have been reported, there is a concern about postoperative impingement between the preserved femoral neck and the acetabular component. There were few reports about kinematics after hip resurfacing. Therefore, the purpose of this study was to investigate the postoperative motion analysis after hip resurfacing using a noble dynamic flat-panel detector (FPD) system by which clear sequential images were obtained with low dose radiation exposure. Materials and methods. 11 patients (mean age: 47.8 ± 7.4), 15 hips were included in this study. There were ten men and one woman. The preoperative diagnoses were ON of the femoral head in 10 hips, OA in 3 hips, and others in 2 hips. Mean postoperative follow-up period was 25.1 ± 21.6 months. Femoral anteversion, cup inclination and cup anteversion were measured on computed tomography and plain radiograph. Impingement signs such as the reactive osteophyte formation and divot around the femoral neck were also investigated on the anteroposterior (AP) and lateral radiographs. Sequential images of active and passive flexion motion in 45-degrees semilateral position, and active abduction motion in a supine position were obtained using a noble dynamic FPD system. Results. Mean femoral anteversion was 13.2° ± 9.1° and mean cup inclination and anteversion were 35.4° ± 2.3° and 6.8° ± 3.9°, respectively. The reactive osteophyte formation apeared in 1 hip (6.7%) on AP radiograph and 4 hips (26.7%) on lateral radiograph, and divot sign was observed in 1 hip (6.7%) on each radiographs. The location of the impingement signs were mostly observed at the anteroinferior portion of the femoral neck. In motion analysis, impingement between the femoral neck and the acetabular component was detected in 12 hips (80.0%) in flexion motion and 2 hips (13.3%) in abduction motion (Figure). There were no findings of the subluxation between the acetabular and femoral component after the impingement, but cooperative motion of lumber and pelvic flexion was occurred. None of the patients who had a impingement signs on plain radiographs and motion analysis had any symptoms and pain during hip motion. Discussion and conclusion. Postoperative motion analysis is a noble and useful technique and that can detect various findings which could not be detected by the routine static radiographs. Also, postoperative kinematics after hip resurfacing remains unknown and we investigated it in detail using a noble dynamic FPD system. The present study indicated that impingement between the preserved femoral neck and the acetabular component and consequent cooperative motion of lumber and pelvic flexion were similar to the physiological motion of the nomal hip joint. No sign of the subluxation between the component proved the good stability of the resurfacing articulation. Proprioception of the preserved femoral neck can be related to this unique kinematics

Background. Few clinical hip score include toe-reach motion after THA (put-on-socks, shoe-ties, nail-cuttingãf»ãf»ãf») Some reports have shown whether THA patients can put on socks or not in daily activity, and not shown how they can do it. The purpose of this study is to investigate real pattern of put-on-socks motion in daily activities after THA, and to evaluate the characteristics of the motion quantitatively. Materials and Methods. 1st step. Reviewing clinical chart, we investigated highly frequent pattern in wearing socks motion that would cause dislocation in ADL in 100 patients with normal lower extremities except for hip more than one year after THA, then, we classified the motion pattern. 2nd step:. Using an optical 3-D motion analysis we measured necessary angles on trunk, hip, knee and ankle in 10 healthy volunteers and 20 THA subjects one month postoperatively, while the volunteers or THA subjects make such frequent patterns of movement based on the 1. st. step. ALL joint angle was defined as “zero” in static standing position. We also compared the angles in THA subjects with those of the volunteers. Motion analysis technology with optical sensors is;. 1). Track 30 infrared reflection sensors on subjects' body surface with infrared camera in the requested motions (MAC3D system, Motion Analysis, USA). 2). Collect 3-D coordinates of 30 sensors' positions over time during subjects' motions. 3). Calculate joint angle, driving 3-D installed skeletal model combined with motion data collected in 2) on display over time (SIMM, Musculographics). Results. Resulting from clinical chart, most patients (78%) behave in an individual manner regardless of postoperative guidance for prevention of hip dislocation more than 1 year after THA. High incident pattern of the motion was “Leg raising pattern” (26%), and “Trunk flexion pattern” (23%) (Fig. 1). For above two pattern of the socks-wearing motion, 3-D motion analysis showed that maximum hip flexion angle was 78.7±5.2 degrees for leg raising pattern, 80.4±6.8 degrees for trunk flexion pattern, and they were significantly lower than those of the volunteers. Moreover, it showed that maximum ankle dorsal flexion angle was 13.6±10.5 degrees, 9.5±10.5 degrees respectively and they were significantly larger than those of the volunteers. It was not significant between THA patients and volunteers for maximum trunk and knee joint angle during each motion, respectively (Fig. 2, Fig. 3). Hip angle of abduction/adduction or external/internal rotation was within 15 degrees during each motion. Discussion. Most reports refer to early postoperative period, and express ability to do the motion, as indicated posture for prevention of hip dislocation. However, current study showed that most patients (78%) behave in an individual manner more than 1 year after THA. During wearing socks motion, in THA group, compared to control group, hip flexion was lower and ankle dorsal flexion was higher, suggesting compensation for the disability of hip joint with the ankle motion one month after THA

INTRODUCTION. Most total knees today are CR or PS, with lateral and medial condyles similar in shape. There is excellent durability, but a shortfall in functional outcomes compared with normals, evidenced by abnormal contact points and gait kinematics, and paradoxical sliding. However unicondylar, medial pivot, or bicruciate retaining, are preferred by patients, ascribed to AP stability or retention of anatomic structures (Pritchett; Zuiderbaan). Recently, Guided Motion knees have been shown to more closely reproduce anatomic kinematics (Walker; Willing; Amiri; Lin; Zumbrunn). As a design approach we proposed Design Criteria: reproduce the function of each anatomic stabilizing structure with bearing surfaces on the lateral and medial sides and intercondylar; resected cruciates because this is surgically preferred; avoid a cam-post because of central femur bone removal, soft tissue entrapment, noises, and damage (Pritchett; Nunley). Our hypothesis was that these criteria could produce a Guided Motion design with normal kinematics. METHODS & MATERIALS. Numerous studies on stability and laxity showed the ACL was essential to controlling posterior femoral displacement on the tibia whether the knee was loaded or unloaded. Under load, the anterior upwards slope of the medial tibial plateau prevented anterior displacement (Griffen; Freeman; Pinskerova; Reynolds). The posterior cruciate and the downward lateral tibial slope produced lateral rollback in flexion. The Replica Guided Motion knee had 3 bearings (Fig 1). The lateral side was shallow and sloped posteriorly, with a posterior lip to prevent excess displacement. The medial anterior tibial and femoral slopes were increased as in the anatomic knee. In the intercondylar region, a saddle bearing replaced ACL function by controlling posterior femoral displacement. For testing, a typical PS design was used as comparison. A Knee Test Machine (Fig 2) flexed the knee, and applied axial compression, shear and torque to represent a range of functions. Bone shapes were reproduced by 3D printing and collaterals by elastomeric bands. Motion was recorded with a digital camera, and Geomagic to process data. RESULTS. The kinematics of normal knees was the benchmark (Arno). The results for neutral path of motion, and the AP laxity about the neutral path, are shown (Fig 3). The PS showed symmetric motion, with anterior medial sliding and excessive constraint in low and high flexion. For the Replica, the medial condyle remained almost constant, but the lateral side rolled posteriorly with flexion, less than normal to prevent damage to the posterior lateral tibial plastic. The lateral side had similar anterior laxity to anatomic, but more than anatomic in late flexion. Based on 10 parameter motion scoring, the Replica was closer to normal than the PS, 82% cf 51%. DISCUSSION. Functional outcomes after TKA are less than normal, TKA design being a likely factor. The approach shown here is intended to reproduce more anatomic kinematics of neutral path of motion and laxity. Such a Replica Guided Motion knee, based on an anatomic structure/stability approach, could reproduce close to normal kinematics even without the cruciates or a cam-post. This may result in improved functional outcomes, and a closer feeling of a normal knee. For any figures or tables, please contact authors directly (see Info & Metrics tab above).

The evaluation of knee stability is fundamental for the clinical discrimination between healthy and pathological joints, for the design and evaluation of prostheses and for the definition of articular models. Knee stability can be quantified by measuring the relation between applied single-axis constant loads and corresponding tibio-femoral displacements (i.e., translations and rotations), namely the joint stiffness, at a given flexion angle. No many studies are available in the literature on this topic [1–3]. In particular, the translations/rotations along/about directions different from the loaded one were not deeply investigated. A fresh frozen lower-limb specimen (female, 63 years old, weight 68 Kg, height 158 cm) was considered. The forefoot and all soft tissues outside the knee were removed by a surgeon, keeping the knee joint capsule intact. A stereophotogrammetric system (Vicon Motion Systems Ltd.) was used to measure the femoro-tibial relative motion by two trackers fixed to the bones, thus introducing no soft-tissue artifact. The specimen was then mounted on a test rig capable to exert general loading conditions [4], and constant loads were applied to the tibia: ±100 N in antero-posterior (AP) and medio-lateral (ML) direction; ±10 Nm about abb-adduction (AA) and in-external (IE) rotations. Loads were applied approximately at the mid-point between the lateral and medial epicondyles, and were kept constant while the femur was flexed over a 135° range. Displacements were defined with respect to the joint natural motion (RTNM), also registered with the same rig. The relative motion of the bones was expressed by a standard joint coordinate system [5]. Considerable translations/rotations appeared also on different directions than the loaded one. At 90° of flexion, an anterior load of +100 N produced 5.5 mm of anterior translation, 10.9 mm of medial translation and 12° of external rotation of the tibia (RTNM). When not directly loaded in ML and IE directions, the tibia translated medially and rotated externally, independently from the sign of the applied load: at 90° of flexion, an AA torque of +10 Nm and −10 Nm produced respectively 5 mm and 8.9 mm of medial translation, and 5.5° and 7.5° of external rotation of the tibia (RTNM). The load/displacement relation was highly non linear also for the loading direction. At 90° of flexion, IE torques of +10 Nm and −10 Nm produced respectively 3.6° of internal and 14.2° of external rotation of the tibia (RTNM). The knee joint structures make the relation between applied loads and bone displacements highly non linear. As a result, a load acting on one direction produces a complex three-dimensional joint motion. Future work will extend the presented analysis on several specimens, also increasing the magnitude and the number of loading conditions

Introduction. Gait analysis systems have enjoyed increasing usage and have been validated to provide highly accurate assessments for range of motion. Size, cost, need for marker placement and need for complex data processing have remained limiting factors in uptake outside of what remains predominantly large research institutions. Progress and advances in deep neural networks, trained on millions of clinically labelled datasets, have allowed the development of a computer vision system which enables assessment using a handheld smartphone with no markers and accurate range of motion for knee during flexion and extension. This allows clinicians and therapists to objectively track progress without the need for complex and expensive equipment or time-consuming analysis, which was concluded to be lacking during a recent systematic review of existing applications. Method. A smartphone based computer vision system was assessed for accuracy with a gold standard comparison using a validated ‘traditional’ infra-red motion capture system which had a defined calibrated accuracy of 0.1degrees. A total of 22 subjects were assessed simultaneously using both the computer vision smartphone application and the standard motion capture system. Assessment of the handheld system was made by comparison to the motion capture system for knee flexion and extension angles through a range of motion with a simulated fixed-flexion deformity which prevented full extension to assess the accuracy of the system, repeating movements ten times. The peak extension angles and also numerous discrete angle measurements were compared between the two systems. Repeatability was assessed by comparing several sequential cycles of flexion/extension and comparison of the maximum range of motion in normal knees and in those with a simulated fixed-flexion deformity. In addition, discrete angles were also measured on both legs of three cadavers with both skin and then bone implanted fiducial markers for ground truth reliability accounting for skin movement. Data was processed quickly through an automated secure cloud system. Results. The smartphone application was found to be accurate to 1.47±1.05 degrees through a full range of motion and 1.75±1.56 degrees when only peak extension angles were compared, demonstrating excellent reliability and repeatability. The cadaveric studies despite limitations which will be discussed still showed excellent accuracy with average errors as low as 0.29 degrees for individual angles and 4.09 degrees for an average error in several measurement. Conclusion. This novel solution offers for the first time a way to objectively measure knee range of motion using a markerless handheld device and enables tracking through a range of assessments with proven accuracy and reliability even accounting for traditional issues with the previous marker based systems. Repeatability for both computer vision and motion capture have greater extrinsic than intrinsic error, particularly with marker placement - another benefit of a markerless system. Clinical applications include pre-operative assessment and post-operative follow-up, paired with surgical planning (including with robots) and remote monitoring after knee surgery, with outcomes guiding treatment and rehabilitation and leading to reduced need for manipulation under anaesthesia and greater satisfaction

Introduction. The reliability of currently available proximal humeral fracture classi?cation systems has been shown to be poor, giving rise to the question whether a more objective measure entails improved predictability of surgical outcome. This study aims to apply a novel software system to predict the functional range of motion of the glenohumeral joint after proximal humeral fracture. Method. Using a validated system that simulates bone-determined range of motion of spheroidal joints such as the shoulder joint, we categorically analysed a consecutive series of 79 proximal humeral fractures. Morphological properties of the proximal humerus fractures were related to simulated bone-determined range of motion. Results. The interobserver variability of range of motion assessment using our system showed excellent agreement (0.798). Maximal glenohumeral abduction and forward ?exion of intra-articular fractures were 34.3±6.6 SE and 60.7±12.4 SE degrees. For fractures with a displaced greater tuberosity abduction was 75.0±5.9 SE and forward flexion was 118.2±4.9 SE degrees, whilst for fractures where both tuberosities had been displaced they were 60.0±10.9 SE and 69.6±13.4 SE degrees respectively. For non-intra articular fractures without displaced tuberosities movements were 89.3±3.3 SE and 122.6±3.4 SE degrees respectively. The head inclination angle was positively correlated with maximum abduction (0.362, p = 0.014). Offset was negatively correlated with maximum abduction, but not statistically signi?cant (0.834, p = 0.087). Conclusion. This study has demonstrated a novel and effective tool allowing the prediction of functional motion after proximal humeral fracture based on bone anatomy. The study demonstrates that intra-articular fractures generally have the worst prognosis with regards to bone-determined ROM. Fractures with displaced tuberosities show more motion limitations for abduction than for forward ?exion. A reduced head inclination angle is a strong predictor of limited bone-determined range of motion for all types of proximal humerus fractures

Currently, the consensus regarding subscapularis tendon repair during a reverse total shoulder arthroplasty (rTSA) is to do so if it is possible. Repair is thought to decrease the risk of dislocation and improve internal rotation but may also increase stiffness and improvement in internal rotation may be of subclinical benefit. Aim is to retrospectively evaluate the outcomes of rTSA, with or without a subscapularis tendon repair.

We completed a retrospective review of 51 participants (25 without and 26 with subscapularis repair) who received rTSR by a single-surgeon using a single-implant. Three patient reported outcome measures (PROM) were assessed pre-operatively and post-operative at twelve months, as well as range of movement (ROM) and plain radiographs. Statistical analysis utilized unpaired t tests for parametric variables and Mann-Whitney U test for nonparametric variables.

External Rotation ROM pre-operatively was the only variable with a significance difference (p=0.02) with the subscapularis tendon repaired group having a greater range. Pre- and post-operative abduction (p=0.72 & 0.58), forward flexion (p=0.67 & 0.34), ASES (p=0.0.06 & 0.78), Oxford (p=0.0.27 & 0.73) and post-operative external rotation (p=0.17)

Greater external rotation ROM pre-operatively may be indicative of the ability to repair the subscapularis tendon intra-operatively. However, repair does not seem to improve clinical outcome at 12 months.

There was no difference of the PROMs and AROMs between the subscapularis repaired and not repaired groups for any of the variables at the pre-operative or 12 month post operative with the exception of the external rotation ROM pre-operatively. We can conclude that from PROM or AROM perspective there is no difference if the tendon is repaired or not in a rTSR and indeed the patients without the repair may have improved outcomes at 12 months.

Articulating cartilage experiences a multitude of biophysical cues. Due to its primary function in distributing load with near frictionless articulation, it is clear that a major stimulus for cartilage homeostasis and regeneration is the mechanical load it experiences on a daily basis. While these effects are considered when performing in vivo studies, in vitro studies are still largely performed under static conditions. Therefore, an increasing complexity of in vitro culture models is required, with the ultimate aim to recreate the articulating joint as accurately as possible. We have for many years utilized a complex multiaxial load bioreactor capable of applying tightly regulated compression and shear loading protocols. Using this bioreactor, we have been able to demonstrate the mechanical induction of human bone marrow stromal cell (BMSC) chondrogenesis in the absence of exogenous growth factors. Building on previous bioreactor studies that demonstrated the mechanical activation of endogenous TGFβ, and subsequent chondrogenesis of human bone marrow derived MSCs, we have been further increasing the complexity of in vitro models. For example, the addition of high molecular weight hyaluronic acid, a component of synovial fluid, culture medium leads to reduced hypertrophy and increased glycosaminoglycan deposition. The ultimate aim of all of these endeavors is to identify promising materials and therapies during in vitro/ ex vivo studies, therefore reducing the numbers or candidates that are finally tested using in vivo studies. This 3R approach can improve the opportunities for success while leading to more ethically acceptable product development pathways.

Introduction:. Reverse shoulder arthroplasty (RSA) has proven to be a useful tool to manage a variety of pathologic conditions. However, inconsistent improvement in motion occurs in patients who have undergone RSA for revision shoulder arthroplasty, proximal humeral fracture sequelae, and treatment of infection. Additional factors that have been suggested to produce poor postoperative range of motion (ROM) may be associated with patient's factors such as poor preoperative range of motion and surgical factors such as inability to lengthen the arm. The purpose of this study was to analyze multiple factors which may be responsible in predicting motion after RSA. It is our hypothesis that intraoperative ROM is most predictive of postoperative ROM. Methods:. Between February 2003 and April 2011 566 patients (225 male and 341 female) treated with a RSA for 1) acute proximal humeral fracture (11), 2) Sequeala of proximal humeral fractures (31), 3) cuff tear arthropathy (278), 4) massive cuff tear without arthritis (78), 5) failed shoulder arthroplasty (168) and 6) infection (29) were evaluated with preoperative range of motion, intraoperative range of motion and range of motion at a minimum of 2-year postoperative follow up. A single observer recorded intraoperative flexion (IFF) in 30° increments. Preoperative and postoperative ROM was recorded by patient video or a previously validated patient performed outcome measure. Preoperative diagnosis was confirmed by radiographic and intraoperative information. 477 patients had preoperative and postoperative radiographs available for analysis of acromial-greater tuberosity distance change (AGT) which was utilized to calculate arm lengthening. A regression analysis was then performed to determine which factors were most influential in predicting postoperative active range of motion. Results:. IFF was the strongest predictor of final postoperative ROM, followed by gender and preoperative ROM. Age, AGT and treatment for the purposes of revision, infection or massive cuff tear were not significant independent predictors of postoperative ROM. Compared to patients with intraoperative forward elevation of ≤60 degrees, patients with intraoperative elevation of 90 degrees gained 16° in postoperative forward elevation (p = 0.029), patients with intraoperative elevation of 120 degrees gained roughly 38° in postoperative forward elevation (p < 0.001) and patients with intraoperative elevation of 150 degrees gained roughly 49 degrees in postoperative forward elevation (p < 0.001). Patients with 120° or more intraoperative elevation were nine times more likely (OR = 9.04, 95%CI: 4.96–16.47) than patients with 90° or less intraoperative elevation to have postoperative forward elevation of 150° or more (top 25% of postoperative results). Conclusions:. Intraoperative forward flexion is strongest predictor postoperative ROM. Surgeons are able to use intraoperative motion as a powerful tool in decision making regarding soft tissue tension in reverse shoulder arthroplasty, therefore by maximizing intraoperative motion, patients have a much greater likelihood of improvement in their final active motion

Information regarding the axes of motion or centers of rotation of the normal cervical spine are necessary to evaluate the similarity of the motion allowed by cervical total disc replacement designs to the natural cervical spine. However, little data has been presented previously regarding the three-dimensional axes of motion of the cervical spine for the three primary motions of flexion/extension, lateral bending and axial rotation. The objective of this study was to measure the three-dimensional axes of motion (Helical axis of Motion) in the natural sub-axial cervical spine using ex-vivo human cadaveric cervical spines. To measure the Helical Axes of Motion (HAM) for the sub-axial cervical spine under flexion/extension, lateral bending and axial torsion moments and evaluate the effect of a physiologic axial preload on the axes locations and orientations. This study demonstrated the feasibility of calculating the HAM in the cervical spine using an ex-vivo experimental protocol. The HAM is a three-dimensional analogue to the two-dimensional center of rotation. The data presented here can be used to evaluate the similarity of the motion allowed by total disc replacement designs to the natural cervical spine. They can also be applied for the characterization of spinal trauma, pathology, instability or surgical devices. The orientation and locations of the HAMs for axial torsion loading are presented in Figure 1. In flexion/extension the HAM penetrated the sagittal plane near the posterior aspect of the vertebral body and near the cranial endplate. The lateral bending results were similar to the axial torsion results. The addition of axial preload had little effect on the position and orientation of the HAM. Sub-axial (level C2-C7) cadaveric cervical spine functional spinal units (n=7) were subjected to pure moments of 1 Nm. Specimens were tested with and without axial preloads of 200 N. Vertebral kinematics were measured using an optoelectronic motion analysis system. These data are particularly applicable to the evaluation and design of “motion-retaining” devices such as total disc replacements, facet joint replacement systems or flexible stabilization systems. Please contact author for figures and diagrams

Due to technology advancement, many studies have reported on in-vivo human knee kinematics recently (Dannis, 2005; Moro-oka, 2008; Tashman, 2003; Koo, 2008). This abstract summarized the joint kinematics during three motions usually seen in our daily living, i.e. gait, step-up (stair ascending) and single-legged lunge that was measured using a combined dual-fluoroscopic imaging system and MRI based modeling technique (Li, 2008). Cartilage contacts or condylar motion using transepicondylar axis (TEA)/geometric center axis (GCA) were used to describe the motion characters of the knee during these motions. In the treadmill gait, the movement of the medial femoral condyle along the anteroposterior direction was significantly greater than that of the lateral femoral condyle during the stance phase using either TEA (9.7 ± 0.7 mm vs. 4.0 ± 1.7 mm, respectively; p < 0.01; Fig. 1A) or GCA (17.4 ± 2.0 mm vs. 7.4 ± 6.1 mm, respectively; p < 0.01; Fig. 1B). A “lateral-pivoting” of the knee was observed (Kozanek, 2009). In the step-up motion, both medial and lateral contact points moved anteriorly on the tibial articular surfaces along the step-up motion path. The contact points on the medial and lateral tibial plateau moved anteriorly (13.5 ± 3.2 mm vs. 10.7 ± 5.0 mm, respectively; p > 0.05; Fig. 2A) with knee extension. Using the TEA (Fig. 2B), the femoral condylar motions presented a similar pattern as the contact points; nonetheless, using the GCA (Fig. 2C), the femoral condylar motion pattern was dramatically different. The medial condyle moved anteriorly, while the lateral condyle shifted posteriorly. However, none of them showed a significant pivoting phenomenon (Li, 2013). In the single-legged lunge, both medial and lateral contact points moved similarly before 120° of knee flexion, but the lateral contact moved posteriorly and significantly more than the medial compartment in high flexion (1.9 ± 2.1 mm vs. 4.8 ± 2 mm, respectively; p < 0.05). The single-legged lunge didn't show a single motion pattern (Fig. 3) (Qi, 2013). These data provide baseline knowledge for the understanding of normal physiological function of the knee during gait, step-up and lunge activities. The findings of these studies demonstrated that knee joint kinematics is activity-dependent and indicated that the knee joint motions could not be described using a single motion character such as “medial-pivoting” that has recently been popularized in total knee arthroplasty design areas

Objectives. Cadaveric models of the shoulder evaluate discrete motion segments using the glenohumeral joint in isolation over a defined trajectory. The aim of this study was to design, manufacture and validate a robotic system to accurately create three-dimensional movement of the upper body and capture it using high-speed motion cameras. Methods. In particular, we intended to use the robotic system to simulate the normal throwing motion in an intact cadaver. The robotic system consists of a lower frame (to move the torso) and an upper frame (to move an arm) using seven actuators. The actuators accurately reproduced planned trajectories. The marker setup used for motion capture was able to determine the six degrees of freedom of all involved joints during the planned motion of the end effector. Results. The testing system demonstrated high precision and accuracy based on the expected versus observed displacements of individual axes. The maximum coefficient of variation for displacement of unloaded axes was less than 0.5% for all axes. The expected and observed actual displacements had a high level of correlation with coefficients of determination of 1.0 for all axes. Conclusions. Given that this system can accurately simulate and track simple and complex motion, there is a new opportunity to study kinematics of the shoulder under normal and pathological conditions in a cadaveric shoulder model

Introduction: There is an increasing interest in the concept of motion preservation in cervical disc degeneration surgery. There is still a controversy regarding the effect of posterior placement of the disc on the segmental motion of the treated level. The objective of this study is to assess the effect (if any) of posterior placement of the LP Prestige disc on the motion. To our knowledge this is the first study to assess the relation of posterior placement on the motion. Material and Methods: We retrospectively reviewed 186 prosthesis implanted in 130 patients who underwent an LP Prestige cervical disc replacement and decompression. The distance between the posterior edge of the lower plate of the LP Prestige disc and the posterior wall of the corresponding vertebra was measured. The measurement was performed on a digitalized lateral view x-rays. The posterior placement measurement was correlated to the range of motion of the device on the same level and also on the level above and bellow. Results: The average age was 46.7 years (range 33–66). The mean posterior placement was 2.96 mm (range 0–6 mm). Range of motion (full flexion to full extension) of the prosthesis was 9.41 degrees (range 0.2–22). Average followup was 2.3 years. Statistical analysis showed no statistical significant correlation between the posterior placement of the disc and the motion of disc (flexion to extension, flexion to neural and neutral to extension). The p value was 0.259, 0.379 and 0.623 respectively. There was no correlation between the placement of the disc and the motion of the level above and bellow the operated level. Conclusion: We conclude from our study that there is no correlation between the posterior placement of the Prestige LP and the segmental motion of the prosthesis and the level above and bellow

Introduction: Cervical range of motion is affected by a wide variety of pathologies and is routinely measured in clinical assessment of the neck. It is therefore crucial to use a method that is both accurate and reliable but that is also non-invasive and inexpensive. This study assessed cervical range of motion using different methods of measurement, namely the universal goniometer and the cervical range of motion (CROM) goniometer. These methods were then compared with each other. In addition, we were interested in determining whether a single component of neck movement is representative of total cervical range of motion. Methods: 50 healthy subjects between the ages of 18–87 with no shoulder or spine pathology were asked to perform six active neck movements, flexion, extension, lateral flexion and axial rotation while the movements were measured first using the universal goniometer and then with the CROM goniometer. The CROM goniometer has been shown previously to have excellent validity and reliability. The researchers were trained to use the measuring techniques prior to data collection. All measurements were performed by the same researcher for each subject and the two researchers alternated between subjects. Results: Comparison between the universal goniometer and the CROM goniometer was performed using Bland and Altman plots. This revealed that 60.6% of universal goniometer readings were within ±5° of the CROM reading; however 31.6% of readings differed by > ±5° and 7.8% differed by > ±10°. The interobserver variance was calculated and there was excellent agreement between the two researchers for both the universal goniometer and CROM goniometer, with an intraclass correlation coefficient of ≥0.80 for every movement. Extension was the most predictive of total neck movement (Pearson coefficient 0.643, p < 0.001). This continues to be the case even when the negative effect of age on range of motion is taken into account. Discussion: The finding that extension was the most representative neck movement has implications for the assessment of cervical motion. Accordingly, if a single neck movement is measured to represent total range of motion, extension should be used. The comparison between the CROM and universal goniometer demonstrated that the majority of goniometer readings were within 5° of the CROM result; however, this was not consistently the case. Given that the CROM is a valid and reliable method of measuring neck movement, the inconsistency between the goniometer and CROM can be taken as inaccuracy on the part of the universal goniometer. As the interobserver variance is excellent one can assume that these results are reproducible and that the errors observed are a true reflection of the limitations of the device

Foot pain and related problems are quite common in the community. It is reported that 24% of individuals older than 45 experienced foot pain. Also, it is stated that at least two thirds of individuals experiences moderate physical disability due to foot problems. In the absence of evaluation of risk factors such as limited ankle dorsiflexion in the early period of the diseases (Plantar fasciitis, Achilles Tendinopathy e.g.) and the lack of mobile systems with portable remote access, foot pain becomes refractory/chronic foot pain, secondary pathologies and ends with workload of 1., 2. and 3rd level healthcare services. In the literature, manuel and dijital methods have been used to analyze the ankle range of motion (ROM). These studies are generally based on placing protractors on the image and / or angle detection from inclination measurement by using the gyroscope sensor of the mobile device. Some of these applications are effective and they are designed to be suitable for measuring in a clinical setting by a physician or physiotherapist. To the best of our knowledge, there is no system developed to measure real-time ankle ROM remotely with collaboration of the patients. In this research, we proposed to develop an ankle ROM analyze system with smart phone application that can be used comfortably by subjects. We present a case of a 22-year-old male with a symptomatic pes planus. The mobile application, which was used for data collection, was designed and implemented for Android devices. Initially, before the mobile application home page is opened, a consent page was submitted to the acceptance of individual within the scope of Law (KVKK) data privacy. Then, the participant was asked to state his sociodemographic characteristics [age, gender, height, weight] and dominant side. No history of foot-ankle injury, trauma, and surgery was recorded. Activity pain of the foot was 6 according to visual anolog scale (VAS) in the mobile application. His ankle dorsiflexion was 15 ° by manuel goniometer. Besides, server was responsible for storing the collected data and ROM measurement. ROM was calculated by processing the foot video which was sent through the mobile application. During the processing phase, a segmentation model was used which was trained with image process and deep learning methods. With the developed system, we obtained the manual goniometric measurement result with 2 degrees deviation. As the application is calibrated, it is expected to approach the actual measurement of ROM. We can conclude that mobile app-goniometer result in dorsiflexion measurement is a novel promising evaluation method for ankle ROM. it will be easy and practical to detect and monitor risk factor of the diseases, decrease medical costs, provide health services in rural areas, and contribution to life quality and to reduce the workload on physicians and physiotherapist

Recently, several smartphone applications (apps) have been developed and validated for ankle ROM measurement tools like the universal goniometer. This is the first innovative study introduces a new smartphone application to measure ankle joint ROM as a remote solution. This study aimed to assess the correlation between smartphone ROM and universal goniometer measurements, and also report the evaluation of the DijiA app by users.

The study included 22 healthy university students (14F/8M; 20.68±1.72 years) admitted to Yeditepe University. Fourty four feet was measured by both the universal goniometer (UG) and DijiA app. The datas were analyzed through using the intraclass correlation coefficient (ICC). The DijiA app was evaluated by usability testing with representative users.

Pearson correlation coefficient test showed moderate correlation between the DijiA and UG for dorsiflexion (DF) and plantar flexion (PF) measurements (Pearson correlation coefficient: r=0.323, for DF; r=0.435 for PF 95% confidence interval). The application usability was found as high with 76.5 average score and users liked it.

The DijiA app may be a more convenient and easy way to measure ankle DF and PF-ROM than UG. It can be used to evaluate ROM in clinical practice or home using as a personal smartphone.

We sought to evaluate the early post-operative active range-of-motion (AROM) between robotic-assisted total knee arthroplasty (raTKA) and conventional TKA (cTKA). A secondary data analysis on a global prospective cohort study was performed. A propensity score method was used to select a matched control of cTKA from the same database using 1:1 ratio, based on age, sex, BMI, and comorbidity index. This resulted in 216 raTKA and cTKA matched cases. Multivariable longitudinal regression was used to evaluate difference in ROM over time and values are reported as least squares means (95% confidence interval). The longitudinal model tested the treatment effect (raTKA vs cTKA), time effect, and their interaction with control on covariance of patients ‘s age, sex, BMI, comorbidity and pre-operative flexion. Logistic regression was used to analyze the active flexion level at one month (cut by 90°) and three months (cut by 110°).

At one-month postoperative the raTKA cases had more AROM for flexion by an average of 5.54 degrees (p<0.001). There was no difference at three months (p=0.228). The raTKA group had a greater improvement from pre-operative values at both one-month, with an average 7.07° (3.6°, 10.5°, p<0.001) more improvement, and at three-months with an average improvement of 4° more (1.61°, 7.24°, p=0.0115). AROM for extension was lower overall in the raTKA group by an average of 0.44° (p=0.029). The raTKA patients had higher odds of achieving ≥90° of flexion at one-month (OR 2.15, 95% CI 1.16, 3.99).

raTKA resulted in greater AROM flexion gains in the early postoperative period than cTKA. Additional research is needed to understand if these earlier gains in AROM are associated with improved patient satisfaction and continued improvements with time.

Background: Intervertebral motion is often assumed to be altered with back pain, however, the patterns are inaccessible to measurement in live subjects. A method for digitally tracking and analysing fluoroscopic images of the vertebrae of subjects who are undergoing standardised passive motion has recently been brought into clinical use for the assessment of surgical fusions. We have studied the differences between the behaviour of spinal linkages in subjects who are asymptomatic, and those who have had fusion operations. This paper describes the reliability, ranges and qualitative features of intervertebral motion patterns in 27 asymptomatic subjects and 3 fusion patients. Methods and results: Thirty asymptomatic male volunteer subjects aged 19–40, underwent 2 –20 second sessions of fluoroscopic screening during 80 degrees of lumbar spine bending within 20 minutes of each other. Intervertebral sidebending motion from L2–5 was measured in 27 subjects whose images were judged suitable for tracking. Approximately 120 digitised images throughout each motion sequence were analysed 5 times by 2 blinded observers for intervertebral range and each result averaged. The intra-subject biological error (RMS), for range of intervertebral motion was 2.75° for Observer1 and 2.91° for Observer 2. The interobserver error for tracking the same screenings was 1.86° (RMS). At almost all levels, these motion patterns were remarkably regular. Four male patients aged 33, 44, 45 and 52 years, who had undergone different spinal stabilisation procedures consisting of flexible stabilisation (DNESYS), posterior instrumented fusion, and anterior interbody fusion with facet fixation were investigated. Images were acquired and analysed in the same way except that a larger number of images (500 per screening) was utilised in each case. Four operated levels and 2 adjacent levels were analysed. All motion patterns were easily distinguishable from those of the normal subjects. The PLIF and DYNESYS stabilisations demonstrated no motion at the instrumented levels. The anterior inter-body fusion-transfacet fixation patient was shown to have developed a pseudarthrosis. Conclusions: Detailed lumbar intervertebral bending patterns in asymptomatic subjects were distinguishable from the fused and adjacent-to fused segments in operated patients. Results suggest that there is sufficient reliability in the method to evaluate lumbar intersegmental ranges and motion patterns for fusion assessment

Introduction. Advancements in knee surgery require a profound understanding of knee mechanics. However, there are seemingly contradicting reports regarding certain aspects of normal knee function, such as the location of the pivot of internal-external rotation in the transverse plane. Among others, it has been suggested to be located close to the knee center or in the medial compartment. We hypothesized that this apparent contradiction is a result of different studied knee motions and that it can be explained by the underlying envelopes of motion. The study objective was to characterize normal knee behavior in-vitro with an emphasis on pivot location. Methods. Thirty-four cadaveric human knee specimens (Age: 61±8 years, BMI: 25±7) underwent CT and MR imaging and load controlled in-vitro testing using an industrial robot (KUKA, Augsburg, Germany). The robot simulated passive knee flexion and assessed the envelopes of motion through anterior-posterior (AP, ±100 N), medial-lateral (ML, ±100 N) and internal-external (IE, ±6 Nm) laxity testing at five flexion angles. Kinematics were expressed by the femoral flexion facet centers (FFC). The pivot location was determined for IE laxity testing and passive flexion by computing the center of transverse femoral rotation in a least squares sense. Groups were compared by one-way ANOVA (α = 0.05). Results are stated as average ± standard deviation. Results. During IE laxity testing the pivot was located centrally, exhibiting a small medial offset from the tibia center (Fig. 1). The medial offsets were 4.1±3.0 mm, 3.6±1.9 mm, 4.4±1.9 mm, 5.3±2.0 mm, and 5.4±2.2 mm at 0°, 30°, 60°, 90° and 120° of flexion. In contrast, the passive flexion pivot location was close to the medial plateau border (Fig 2.). Its medial offset from the center amounted to 36.0±11.7 mm and was significantly larger than any offset detected during IE rotation at a given flexion angle (p « 0.001). The resulting envelopes of motion corresponded to these findings (Fig. 3). The average AP laxities of the medial and lateral FFCs were 14.9±2.9 mm and 17.1±3.0 mm whereas laxity at the knee center was only 6.0±2.8 mm. The average IE laxity was 37.8±6.1°. Over the arc of flexion, the envelope centers shifted posteriorly by −0.3±3.1 mm, 14.5±3.9 mm and 10.3±2.9 mm for the medial FFC, lateral FFC and the knee center respectively. Discussion and Conclusion. Our results confirm that the pivot location can vary and is influenced by the type of knee motion. Furthermore, fundamental characteristics of knee biomechanics such as AP stability, IE laxity as well as femoral rollback and external rotation with flexion help explain what could be construed as contradictions in the literature. AP stability and rollback are controlled centrally by the cruciate ligaments. A central pivot during IE laxity testing is a direct consequence of the central AP stabilization. However, a medial pivot during passive flexion results from the superposition of the rollback guided by the cruciates and external rotation with flexion. This current study provides a comprehensive evaluation of the intact knee that when examined as a whole begins to explain contradictory data in the literature and provides a broader picture of passive knee kinematics

Purpose. This study was to investigate the effect of posterior tibial slope (PTS) on the kinematics in the cruciate-retaining total knee arthroplasty (CR-TKA) using 2- to 3- dimensional registration technique. Material & Methods. A total of 75 knees in 58 patients were recruited and categorized into the following two groups according to PTS. Group A was categorized PTS under 7degrees (n = 33) and group B was categorized PTS over 7 degrees (n = 42). The average age of group A and group B at the time of fluoroscopic surveillance date was 73.5 ± 7.4 years and 74.3 ± 4.5 years, respectively and the average follow-up period from operation date to fluoroscopic surveillance date was 13.8 ± 9.3 months and 16.7 ± 8.6 months, respectively. In vivo kinematics during sequential deep knee bending under weight-bearing condition were evaluated using fluoroscopic image analysis and 2- to 3- dimensional registration technique. Range of motion (ROM), axial rotation, anteroposterior (AP) translations of medial and lateral nearest points of the femoral component relative to the tibial component were measured and compared between the two groups. The nearest points were determined by calculating the closest distance between the surfaces of femoral component model and the axial plane of coordinate system of the tibial component. We defined external rotation and anterior translation as positive. P values under 0.05 was defined as statistically significant. Results. The mean PTS in group A and B were 5.5 ± 1.4°and 9.9 ± 1.9°, respectively. There was no statistically significant difference in the degrees of axial rotation from 0° to 110° of flexion between the two groups (4.9 ± 4.2° vs 5.2 ± 4.2°, p > 0.05), respectively. The hyperextension of group B were significantly larger than group A (−2.3 ± 6.6°vs −9.8 ± 8.7°, p <0.05). The ROM of group B were significantly larger than group A (118.7 ± 10.8°vs 128.7 ± 17.7°, p <0.05). However, there was no significant difference in the maximum flexion between the two groups (116.4 ±10.8°vs 118.9±14.5°, p >0.05), respectively. In terms of AP translation, medial nearest points were located significantly more posterior at 0°, 10°, 30°, 40° of flexion in group B compared to group A. There was no significant difference in the location of lateral nearest points between the two groups during all knee range of motion. Discussion/Conclusion. The results shown in this study demonstrated that the PTS influenced the kinematics and ROM under weight-bearing condition in CR-TKA. The large PTS induced great posterior displacement of medial nearest points during early flexion phase and increased hyperextension between the femoral and tibial components

Patients ≤ 55 years have a high primary TKA revision rate compared to patients >55 years. Guided motion knee devices are commonly used in younger patients yet outcomes remain unknown. In this sub-group analysis of a large multicenter study, 254 TKAs with a second-generation guided motion knee implant were performed between 2011–2017 in 202 patients ≤ 55 years at seven US and three European sites. Revision rates were compared with Australian Joint Registry (AOANJRR) 2017 data. Average age 49.7 (range 18–54); 56.4% females; average BMI 34 kg/m2; 67.1% obese; patellae resurfaced in 98.4%. Average follow-up 4.2 years; longest follow-up six years; 27.5% followed-up for ≥ five years. Of eight revisions: total revision (one), tibial plate replacements (three), tibial insert exchanges (four). One tibial plate revision re-revised to total revision. Revision indications were mechanical loosening (n=2), infection (n=3), peri-prosthetic fracture (n=1), and instability (n=2). The Kaplan-Meier revision estimate was 3.4% (95% C.I. 1.7% to 6.7%) at five years compared to AOANJRR rate of 6.9%. There was no differential risk by sex. The revision rate of the second-generation guided motion knee system is lower in younger patients compared to registry controls

Introduction: Gait analysis studies of patients following ankle arthrodesis have demonstrated a functional gait, largely due to tarsal hypermobility compensating for lost tibio-talar motion. We present a prospective radiographic study comparing the pre and post-operative range of motion of the foot following ankle arthrodesis. In this study, we introduce a radiographic technique using reliable anatomic landmarks to measure sagittal range of motion of the foot after ankle arthrodesis. Materials and Methods: Between 2002 and 2007, we performed 154 arthrodesis procedures of the ankle. Patients were suitable for inclusion in this study if an isolated arthrodesis of the ankle was performed for post traumatic arthritis with a minimum of 1 year follow-up without any additional hindfoot operations. Preoperative and post-operative passive plantar flexion and dorsiflexion radiographs were obtained in a standardized fashion. Anatomic landmarks were then used to measure and compare tibio-talar, mid-tarsal, and subtalar movement. Results: There were 48 patients who met the inclusion criteria for this study. Preoperatively, the mean measured motion was as follows: total sagittal motion 35o, tibio-talar motion18o, mid-tarsal (transverse tarsal + naviculo cuneiform + tarsometatarsal joints) motion 12o (34% of pre-op sagittal arc), subtalar motion 5.5o (15% of pre-op sagittal arc), and mid-tarsal + subtalar motion 17.5o (49% of pre-operative sagittal motion). These changed post operatively to a mean motion as follows: total sagittal motion 18.5o, (52% of preoperative sagittal motion), mid-tarsal motion 10o (28% of pre-op sagittal arc), subtalar motion 10.5o (27% of pre-op sagittal arc), and mid-tarsal + subtalar motion 20.5o (54% of pre-operative sagittal motion). Discussion: This study presents an accurate and reproducible means of measuring the sagittal plane range of motion of the hindfoot and ankle, and documents the presence of increased motion in the subtalar and talonavicular joints after ankle arthrodesis

Summary Statement. An alternative way to assess three dimensional skin motion artefacts of kinematic models is presented and applied to a novel kinematic foot model. Largest skin motion is measured in the tarsal region. Introduction. Motion capture systems are being used in daily clinical practise for gait analysis. Last decade several kinematic foot models have been presented to gain more insight in joint movement in various foot pathologies. No method is known to directly measure bone movement in a clinical setting. Current golden standard is based on measurement of motion of skin markers and translation to joint kinematics. Rigid body assumptions and skin motion artefacts can seriously influence the outcome of this approach and rigorous validation is required before clinical application is feasible. Validation of kinematic models is currently done via comparison with bone pin studies. However, these studies can only assess major bones in a highly invasive way; another problem is the non-synchronous measurement of skin markers and bone pins. Recently the Glasgow Maastricht kinematic foot model, which comprises all 26 foot segments, has been presented. To validate the model we propose a novel non-invasive method for the assessment of skin motion artefact, involving loaded CT data. Patients & Methods. 25 subjects (healthy and pathological feet) have undertaken CT scans. These CT-scans have been obtained in 1 unloaded and 3 varying loading conditions. CT-slices are 3D reconstructed and segmented. The principal axes of the segmented bones were derived from the surface points of the bones. These principal axes are used to compute bone orientation. Subsequently, coordinate systems of bones in the different loading conditions were matched. Markers were translated and rotated to orientations of their corresponding bones. Maximal distance between markers is calculated per subject to asses the influence of skin motion. Results. Preliminary results of 9 subjects show largest positional differences for markers associated with the cuneiform lateralis (5.7 ± 3.2 mm) and cuneiform intermedium (7.7 ± 3.7 mm). Smallest positional differences are found on the hallux proximalis (0.9 ± 0.34mm). Spatial resolution is too small to accurately calculate orientation of smaller bones, therefor distal phalanges 2–5 are not taken into account in the analysis. Discussion/Conclusion. Skin motion is a major cause of inaccuracy in gait analysis. This is the first study presenting an automated non-invasive method to calculate the 3D orientation of skin markers with respect to the coordinate system of the corresponding bone(s). Largest skin motion is measured in the tarsal region. Future work will be in calculation of the effect of skin motion in the accuracy of joint angle calculation

Distal radius fractures (DRF) are the most common fracture type in all age groups combined. Unstable DRF may be surgically managed with volar or dorsal plate fixation. Dorsal plating has traditionally been associated with decreased range of motion (ROM). However, this assumption has not been recently assessed to determine whether functional ROM is achievable (approximately 54o of flexion and 60o of extension) with recent advances in lower profile dorsal plate design. The aim of this study was therefore to compare ROM and patient reported outcome measures between volar and dorsal plating methods for DRF. A meta-analysis was performed to directly compare ROM and DASH scores between dorsal and volar plate fixation for DRF. Separate literature searches for each plating method were performed using MedLine and EMBase on January 28, 2018. Exclusion criteria consisted of non-English articles, basic science articles, animal/cadaver studies, case studies/series, combined operative approaches, papers published more than 20 years ago and paediatric studies. Only articles with at least one year patient follow-up and a) ROM and AO distal radius fracture classification, or b) DASH scores were included. Raw data was extracted from all articles that met inclusion criteria to compile a comprehensive dataset for analysis. Descriptive statistics with z-score comparison for AO classification or a two-tailed independent samples t-test for ROM and DASH scores for dorsal versus volar plating were performed. Significance was defined as p < 0 .05. After rigorous screening, 6 dorsal plating and 43 volar plating articles met inclusion criteria for ROM/AO classification versus 6 dorsal plating and 44 volar plating articles for DASH scores. The weighted means of flexion (dorsal 54.9o, SD 9.3, n=257, volar 61.3o, SD 11.5, n=1906) and extension (dorsal 60.0o, SD 12, n=257, volar 62.8o, SD 11.4, n=1906) were statistically significantly different (both p < 0 .001) between the two plating methods. The volar plating group had a significantly higher proportion of AO type C fractures (dorsal 0.5, n =169, volar 0.6, n=1246, p < 0 .001). The weighted means of reported DASH scores were not significantly different between dorsal (14.01, SD 14.8) versus volar (13.6, SD 12.8) plating (p=0.54). Though mean wrist flexion and extension were statistically different between the dorsal versus volar plating methods, the difference between group means was less than 5o, which is unlikely to be clinically significant. Additionally, we did not find a significant difference in DASH scores between the two plating methods. Taken together, these findings imply that the statistical difference in ROM outcomes are likely not clinically significant and should therefore not dictate choice of plating method for fixation of DRF

Background:. Glenoid component loosening remains as an unsolved clinical problem in total shoulder arthroplasty. Current clinical assessment relies on subjective quantification using a two-dimensional plane X-ray image with arbitrarily defined criteria. There is a need to develop a readily usable clinical tool to accurately and reliably quantify the glenoid component motion over time after surgery. A high-resolution clinical CT has the potential to quantify the glenoid motion, but is challenged by metal artifact from the prosthetic humeral components. The objective of this study is to demonstrate the feasibility of using a clinical CT reconstruction to quantify the glenoid implant motion with the aid of tantalum markers. Methods:. Three spherical tantalum markers of 1.0 mm in diameter were inserted into three peripheral pegs of an all polyethylene glenoid component. The glenoid component was implanted in a sawbone scapula. To determine the effect of metal artifact on quantification of glenoid implant motion, two sawbone humerii were used: one without the prosthetic humeral components and the other with the prosthetic humeral head and stem. Three custom-made translucent spacers with the uniform thickness were placed between the glenoid component and the scapula to produce a gradual translation of the glenoid component from 1 mm to 3 mm. Before and after inserting each spacer, the surface of the glenoid component was digitized by a MicroScribe. The surface points were used to fit a sphere and the corresponding center of the sphere was calculated. The actual translation of the glenoid component was measured as the three-dimensional (3D) distance between the center of the sphere before and after insertion of each spacer. Then, the shoulder model was scanned by a clinical CT with and without the spacers for both humerii conditions. Velcro straps were used to secure the humerus to the glenoid component between the trials. All CT scans were reconstructed in VolNinja software to superimpose the scapula positions (Figure 1). The three tantalum markers were visualized and the center coordinates of the markers were used to measure the 3D distance before and after insertion of each spacer. The accuracy was defined by the difference between the averaged 3D distance measured by CT reconstruction and that measured by the MicroScribe. The standard deviation of the 3D distance measured by each tantalum marker was calculated to evaluate the reliability of the tantalum marker visualization. Results:. Without metal artifact, the accuracy and reliability of quantifying glenoid implant motion using a clinical CT were 0.4 mm and 0.2 mm, respectively (Figure 2). With the presence of metal artifact, the accuracy and reliability were 0.5 mm and 0.4 mm, respectively. The largest difference in quantifying the glenoid component motion with and without the metal artifact was only 0.12 mm. Conclusion:. The current study demonstrated the feasibility of using a clinical CT to quantify glenoid implant motion. With the aid of tantalum markers, a clinical CT can be readily used to quantify the glenoid implant motion accurately and reliably even with the presence of metal artifact from the humeral components

Introduction. The dual mobility design concept for acetabular liners is intended to reduce the risk of dislocation and increase range of motion, but the wear pattern of this design is unclear and may have implications in implant fixation. Additionally, the solid back cups do not have the option for supplementary screw fixation, providing an additional smooth articulating surface for the liner to move against. The objective of this study was to assess cup fixation by measuring implant migration. A secondary objective was to evaluate the mobile bearing motion after rotating the hip. Methods. Thirty subjects were recruited in a consecutive series prospective study and received Anatomic Dual Mobility (Stryker Orthopedics) uncemented acetabular components with mobile bearing polyethylene liners through a direct lateral approach. Femoral stems were cemented (Exeter) or uncemented (Accolade, Stryker Orthopedics). The femur, acetabulum, and non-articulating surface of the polyethylene liner were marked with tantalum beads. Radiostereometric analysis (RSA) exams were performed post-operatively and at 6 weeks, 3, 6, months, and at 1 year. At the 1 year exam, a frog leg RSA exam was performed to assess the mobility of the cup compared to its position during a supine exam. Results. Proximal translation of the cup was 0.16 ± 0.28 mm (range −0.18 to 0.92 mm) and sagittal rotation was 0.08 ± 0.86 degrees (range −1.81 to 2.18 degrees) at 1 year. Analysis of the motion of the mobile bearing liner during the frog leg RSA exam showed total motions of between 0.10 to 5.58 mm (maximum total point motion). Discussion & Conclusions. The migration of the cup has a low group average and is on track to be in the “acceptable” range as defined by Pijls et al. [1] of less than 0.2 mm of subsidence at 2 years. The combination of low subsidence and low sagittal rotations of the cup are favorable predictors of good long-term performance [2]. The wide range of motions of the mobile bearing suggest that in some patients the liner is moving freely, while in a subset of subjects there is no motion. The implications of this in terms of the generation of wear particles and affect on implant migration will be monitored to 3 years

Introduction. Femoroacetabular impingement (FAI) is a common cause of hip symptoms in younger patients. Failure to completely address the deformity yields a poor surgical result. Therefore accurate assessment is imperative to good outcome. Dynamic motion analysis offers improved assessment of the morphological pathology causing FAI. This study aims to compare the differences in measurement reports produced by 3-Dimensional analysis of CT scans for FAI between two systems, Clinical Graphics (Delft, Holland) and Dyonics Hip Plan by Smith & Nephew (London, UK). Patients/Materials & Methods. The senior author uses computerized tomography (CT) with three-dimensional reconstructions and dynamic motion analysis. A series of scans were analysed with both systems, and equivalent data was recorded from each. This included femoral neck version, femoral neck inclination, acetabular anterior coverage (%), acetabular posterior coverage (%), alpha angle at 9, 10, 11, 12, 1, 2 and 3 o'clock positions, centre-edge angle at 12 o'clock, acetabular version and suggested resection. Results. A total of 20 consecutive cases were analysed. Statistical analysis revealed significant differences in measurements of femoral neck version (p<0.001), acetabular anteversion (p=0.032), acetabular posterior coverage (p<0.001), cam deformity alpha angles at 0900, 1000 (p=<0.001), 1100 and 1200(p=0.014) between the two reports produced for each patient. Similar differences were found between the reports for areas of advised resection, particularly at 1200 (p=0.01). Discussion. Dynamic motion analysis offers improved characterisation of FAI pathology. However, femoral head asphericity, off femoral head centre and pelvic tilt can influence FAI measurements. Also, patients may have measurements outside normal ranges, but this may not necessarily equal impingement. Conclusion. Motion analysis software packages currently available work in different ways and produce different reports. It is imperative that the surgeon be aware of how their preferred system works to be able to accurately plan surgery

INTRODUCTION. Femoral stem impingement can damage an acetabular liner, create polyethylene wear, and potentially lead to dislocation. To avoid component-to-component impingement, many surgeons aim to align acetabular cups based on the “Safe Zone” proposed by Lewinnek. However, a recent study indicates that the historical target values for cup inclination and anteversion defined by Lewinnek et al. may be useful but should not be considered a safe zone. The purpose of this study was to determine the effect of altering femoral head size on hip range-of-motion (ROM) to impingement. METHODS. Ten healthy subjects were instrumented and asked to perform six motions commonly associated with hip dislocation, including picking up an object, squatting, and low-chair rising. Femur-to-pelvis relative motions were recorded throughout for flexion/extension, abduction/adduction, and internal/external rotation. A previously reported custom, validated hip ROM three-dimensional simulator was utilized. The user imports implant models, and sets parameters for pelvic tilt, stem version, and specific motions as defined by the subjects. Acetabular cup orientations for abduction and anteversion combinations were chosen. The software was then used to compute minimum clearances or impingement between the components for any hip position. Graphs for acetabular cup abduction vs. anteversion were generated using a tapered wedge stem with a 132º neck angle, a stem version of 15°, and a pelvic tilt of 0°. The only variable changed was femoral head size. Head sizes reviewed were 32mm, 36mm, and a Dual-Mobility liner with an effective head size of 42mm. All femoral head sizes can be used with a 50mm acetabular cup. RESULTS. We found that the “Safe Zone” varies considerably depending on the size of the femoral head used for all subjects. A typical plot illustrating the ROM to impingement is presented in Figures 1a-1c. The area to the left of each curve represents an impingement zone for that motion, and to the right, a non-impingement zone. In all cases the non-impingement area is smaller than the Lewinnek safe zone. Motions like picking up an object and squatting had the greatest influence on impingement. CONCLUSIONS. The true acetabular target for impingement-avoidance motion is much smaller than previously believed and identifies the need to take into account the size of the femoral head to be used. This may explain why approximately 70% of dislocations have been reported to be found even when cups were placed within the Lewinnek safe zone. Certain activities, such as picking up an object and squatting reduce the size of the safe zone. This study supports the need for better patient planning and intraoperative execution for placement of the acetabular component

Four-Corner Fusions (4CF) and Proximal Row Carpectomies (PRC) are common procedures utilized to treat carpal pathologies and radial sided wrist pain. Usually, the range of motion (ROM) and grip strength (GS) is affected by such conditions. Literature quotes significant reduction in ROM (50–60%) and grip strength (GS) (80% of normal) with PRC and 4CF. This study aims to determine the correlation between pre-operative ROM and GS and post-operative ROM and GS for patients with wrist pain undergoing PRC or 4CF. We hypothesize that ROM between pre-operative and post-operative patients does not change, but GS improves. Data from a prospective database of patients with wrist pain was searched to identify patients who have undergone PRC or 4CF with one year follow-up completed in the past two years. 17 such participants were identified. The diagnosis, pre-operative ROM in flexion, extension, radial deviation, ulnar deviation, pronation and supination, as well as GS at time of surgery and at six months and one year follow up were identified and assessed. The data was analysed to determine correlation between pre-and postoperative ROM and GS. The analysis was subdivided to compare patients treated with PRC versus patients with 4CF. No significant difference between pre- and post-operative ROM was detected, except in flexion at 6 months post-operatively. The average flexion was significantly lower at 6 months (p=0.0251) compared to pre-operative levels. Average flexion pre-operatively and at 6 and 12 months was found to be 46.6 (SD=15), 34.3 (SD=13.3), 51.2 (SD=21.5) respectively. Extension was at 41.4 (SD=15.3) pre-operatively and at 33.4 (SD=12.8) and 42.1 (SD=15.5) at 6 and 12 months post-operatively. Similarly, radial and ulnar deviation averages pre-operatively and at 6 and 12 months post-operatively were found to be 11.33 (SD=5.9), 11.9 (SD=4.5), 16 (SD=8.2) [radial deviation] and 24.1 (SD=8.3), 21.4 (SD=7.3), 26 (SD=12.8) [ulnar deviation]. No significant difference was found in GS at 6 months post-operative. However, significant difference at 12 months post-operatively was observed with an average GS of 28.4 kg (SD=12.8) [p=0.0385]. Average GS pre-operatively and at 6 months was 15.8 kg (SD=9.7) and 17.3 kg (SD=8.9) respectively. This study provides an insight on ROM and GS after PRC and 4CF. It shows that patients do not gain or lose ROM after surgery. As expected, GS improves with treatment as the pain diminishes. It is interesting to note that flexion gets worse at 6 months post-operatively before it bounces back to pre-operative levels

For the last few decades there have been several successful reports of TEA of both semi-constrained and non-linked prosthesis: pain relief, improvement of range of motion, functional improvement, and good survival rate of the components. However, other reports also showed that TEA had higher complication rates and lower survival rate than knee and hip joint replacement. To solve this problem some in vitro kinematic studies about TEA have been done and reported. But in vivo research has not been reported yet in the TEA, and it must be done for an essential solution. The aim of this study is to analyze in vivo motion of TEA components using two- to three- (2D/3D) registration technique. Six patients, six elbows were included in this study, having been treated with K-Elbow because of rheumatoid arthritis. The mean age at the operation was 47.2 years The mean duration between the operation and the fluoroscopic surveillance was 56.7 months. Under fluoroscopic examination in the sagittal plane, each patient was asked to bend his or her elbow from full extension to full flexion. Successive elbow motions were recorded as serial digital X-ray images using a digital image intensifier system. In vivo 3D poses of the humeral and the ulnar components were estimated using a 2D/3D registration technique, which uses CAD models to reproduce spatial postures of the humeral and the ulnar components from calibrated single view fluoroscopic images. The algorithm utilizes a feature-based approach to minimize distances between lines drawn from a contour found in the 2D image to the X-ray source and a surface CAD model with iterative computations. The amount of extension/flexion, varus/ valgus, and internal/external rotation angles of the ulnar component for the humeral component were evaluated quantitatively using Euler’s method. Results: The minimum flexion angle between the components was 33.6°± 18.5. Four of the six elbows exhibited inimum flexions of > 30° and the other two elbows exhibited < 30°. One elbow exhibited excessive flexion contracture > 50°. The maximum flexion angle was 126.7° ± 5.5. Only one elbow demonstrated flexion angle < 120° and all the others > 120°. The arc of range of motion was 93.0°±19.4. Concerning the valgus/varus angles between the components, there was a variation among patients. And from 30 to 120° flexion, there was a tendency to incline valgus with the increase of flexion. The mean valgus angle through flexion was −0.1°± 4.3 and the magnitude of displacement of valgus angle was 9.5° ± 4.0. In a similar way, there was a variation among patients about the rotation between the components. And from 30 to 120° flexion, there was a tendency to incline external rotation with the increase of flexion. The mean internal rotation through flexion was −1.0° ± 4.3 and the magnitude of displacement of internal rotation was 8.1°± 3.3

Mobile-bearing (MB) total knee prostheses have been developed to achieve lower contact stress and higher conformity than fixed-bearing total knee prostheses. However, little is known about the in vivo kinematics of MB prostheses especially about the motion of polyethylene insert (PE). And the in vivo motion of PE during squat motion has not been clarified. The objective of this study is to clarify the in vivo motion of MB total knee arthroplasty including PE during squat motion. Patients and methods: We investigated the in vivo knee kinematics of 11 knees (10 patients) implanted with PFC-Sigma RPF (DePuy). Under fluoroscopic surveillance, each patient did a wight-bearing deep knee bending motion. And motion between each component was analyzed using two-to three-dimensional registration technique, which uses computer-assisted design (CAD) models to reproduce the spatial position of the femoral, tibial components, and PE (implanted with four tantalum beads intra-operatively) from single-view fluoroscopic images. We evaluated the range of motion between the femoral and tibial components, axial rotation between the femoral component and PE, the femoral and tibial component, and the PE and tibial component, and AP translation of the nearest point between the femoral and tibial component and between the femoral component and PE. Results: The mean range of hyper-extension was 2.1° and the mean range of flexion of 121.2°. The femoral component relative to the tibial component demonstrated 10.4° external rotation for 0–120 degrees flexion. The tibial component rotated 10.2° externally relative to the PE and the femoral component minimally rotated relative to the PE within ± 5 degrees. In upright standing position, the femoral component already rotated externally relative to the tibial component in 6.3°, and the PE also rotated on average 6.4° externally on the tibial tray. Typically the femoral component relative to the tibial component exhibited a central pivot pattern external rotation from extension to 80° knee flexion. Subsequently from 80 to 120°, bilateral condyles moved backward. In a similar fashion, the femoral component relative to the PE exhibited a central pivot pattern external rotation from extension to 70° knee flexion and subsequently bicondylar rollback from 70 to 120° knee flexion. Discussion and Conclusion: In this study, we evaluated the in vivo motion of PE during squat motion. About this total knee prosthesis, the mobile-bearing mechanism which advantages over fixed-bearing prosthesis to reduce contact stress and keep high comformity might work well, and arc of range of motion was maintained. Furthermore, in upright standing position, the femoral component and tibial component already rotated externally relative to the PE in almost equal measure. This indicated that, self-aligning mechanism, another characteristic of the MB prosthesis might also work well

Introduction. A thorough understanding of wear patterns and failure mechanisms of TKA components in the context of pre-revision knee kinematics is advantageous for component designers, manufacturers and surgeons alike. Traditional gait analysis provides an experimental technique to determine in vivo kinematics but is often limited by its cumbersome nature, infrastructure intensiveness and time. The recent introduction of the KneeKG (Emovi Inc, Canada) as a stand-alone knee motion tracking system which uses infrared technology provides a great opportunity to quickly, easily and routinely monitor patients at the clinical level, especially those being revised for component failure. This pilot study was conducted to examine pre-revision knee kinematics and subsequent wear patterns and failure mechanisms observed on the UHMWPE inserts upon retrieval in a cohort of TKA revision patients. We hypothesize that motion patterns can provide surgeons a unique insight into the status of the UHMWPE insert and implant longevity. Methods. Patients requiring revision due to failure of the UHMWPE insert were recruited in this study after institutional ethical approval and written informed consent of the patients was obtained. Motion of the affected knee was quantified using a stand-alone infrared tracking system (KneeKG, Emovi Inc, Canada) whilst the patient was walking on a treadmill. All analyses were conducted within our institutional Physiotherapy Department. The KneeKG system is composed of passive motion sensors fixed on a validated knee harness, an infrared motion capture system (Polaris Spectra, Northern Digital Inc, USA) and a computer equipped with the Knee3D software suite (Emovi). Following application of the KneeKG trackers a calibration procedure was performed to identify joint centres and define a coordinate system on each body segment. After a treadmill habituation period of between 6 and 10 min, a trial was then conducted at the patient's comfortable treadmill gait speed over 45 sec. Averaged clinical rotations and translations of the tibia as a function of gait cycle were output by the system, and a report highlighting and detailing biomechanical deficiencies as compared to a database of normal controls automatically generated. Following the scheduled revision surgery the retrieved components were formalin-fixed and brought to our laboratory for a routine retrieval workup. All revisions were performed by a single surgeon. Components were analysed using optical and scanning electron microscopy techniques for regions of polishing, burnishing, pitting, delamination, deformation, scratching and embedded debris. Wear maps and scores were generated and correlated with pre-revision kinematics for each patient. Results. The KneeKG was successfully applied to patients in this pre-revision scenario, requiring less than 30 minutes to complete per case. Variations in knee kinematics have been observed, and the analysis of retrieved components is ongoing. Discussion. This study has demonstrated that knowledge of pre-revision knee kinematic patterns can provide a unique insight into wear and failure mechanisms of the UHMWPE liner. Whilst this study is currently limited by a relatively small sample size, recruitment is continuing with a view to the possible generation of odds ratios for UHMWPE insert failure mechanisms based on kinematic signatures

The treatment of osteoarthritis using artificial knee joints is expected to expand further over the next decade. Increasingly, patients expect quicker rehabilitation, improved performance, and high durability. However, economic limitations require a reduced cost for each procedure, as well as early intervention and even preventative measures. The major goal of implant design needs to be a restoration of normal knee mechanics, whether by maximum preservation of tissues, or by guiding surfaces which replicate their function. In this paper it is proposed that total knees should exhibit anatomic knee mechanics, namely medial stability – lateral mobility. Many studies in the past have shown that the neutral path of motion of the anatomic knee, is that the medial side remains relatively immobile in the AP direction, which will impart a feeling of stability, while the lateral side shows posterior femoral displacement with flexion, to obtain a high range of flexion. There is considerable rotational laxity about this neutral path to accommodate a range of positions and activities. Recent studies carried out in our laboratory using an up-and-down crouching machine, and other test machines, have conformed this mechanical behaviour. To further elaborate, we tested eight young male subjects in a 7T MRI machine, where compressive and shear loads were applied. AP displacements occurred laterally but not medially. We attributed this behaviour to the medial meniscus and the tibial bearing geometry under weight-bearing conditions. On the basis of these various studies, we developed a method for the design of Guided Motion knees, which would be implanted without the cruciates, and which would restore anatomic knee mechanics. The method started with the femoral component, where the medial side had features to provide a continuous radius anteriorly, and distally to 75 degrees flexion when a post-cam would contact. This feature would prevent paradoxical anterior femoral sliding in early flexion. Multiple femoral positions were then defined for accommodating anatomic motion, in particular limited AP motion on the medial side, but posterior displacement laterally. Tibial bearing surfaces were generated accordingly. Tests were carried out on the crouching machine and on a Desktop TKR Test machine to compare the TKR motion with anatomic. Although not accurate in all respects, the Guided Motion designs were closer than models of standard TKR’s today. Such Guided Motion designs hold the promise for restoring anatomic knee mechanics and a normal feeling knee

Distal radius fractures (DRF) are the most common fracture type in all age groups combined. Unstable DRF may be surgically managed with volar or dorsal plate fixation. Dorsal plating has traditionally been associated with decreased range of motion (ROM). However, this assumption has not been recently assessed to determine whether functional ROM is achievable (approximately 54 degrees of flexion and 60 degrees of extension) with recent advances in lower profile dorsal plate design. The aim of this study was therefore to compare ROM and patient reported outcome measures between volar and dorsal plating methods for DRF. A meta-analysis was performed to directly compare ROM and Disabilities of Arm, Shoulder and Hand (DASH) scores between dorsal and volar plate fixation for DRF. Separate literature searches for each plating method were performed using MedLine and EMBase on January 28, 2018. Exclusion criteria consisted of non-English articles, basic science articles, animal/cadaver studies, case studies/series, combined operative approaches, papers published more than 20 years ago and paediatric studies. Only articles with at least one year patient follow-up and a) ROM and AO-OTA distal radius fracture classification, or b) DASH scores were included. Raw data was extracted from all articles that met inclusion criteria to compile a comprehensive dataset for analysis. Descriptive statistics with z-score comparison for AO-OTA classification or a two-tailed independent samples t-tests for ROM and DASH scores for dorsal versus volar plating were performed. Significance was defined as p < 0 .05. After rigorous screening, six dorsal plating and 43 volar plating articles met inclusion criteria for ROM/AO-OTA classification versus six dorsal plating and 44 volar plating articles for DASH scores. The weighted means of flexion (dorsal 54.9 degrees, SD 9.3, n=257, volar 61.3 degrees, SD 11.5, n=1906) and extension (dorsal 60 degrees, SD 12, n=257, volar 62.8 degrees, SD 11.4, n=1906) were significantly different (both p < 0 .001) between the two plating methods. The volar plating group had a significantly higher proportion of type C fractures (dorsal 0.5, n =169, volar 0.6, n=1246, p < 0 .001). The weighted means of reported DASH scores were not significantly different between dorsal (14, SD 14.8) versus volar (13.6, SD 12.8) plating (p=0.54). Though mean wrist flexion and extension were statistically different between the dorsal versus volar plating methods, the difference between group means was less than 5-degrees, which is unlikely to be clinically significant. Additionally, there was no significant difference in DASH scores between the two plating methods. Taken together, these findings imply that the statistical difference in ROM outcomes are likely not clinically significant and should therefore not dictate choice of plating method for fixation of DRF

Introduction: The purpose of this study is to determine in vivo femorotibial axial rotation magnitudes and patterns in mobile-bearing posterior stabilized total knee arthroplasty (PS-TKA) and unicondylar knee arthroplasty (UKA) in deep flexion. Material and Methods: Using video fluoroscopy, 12 subjects having a mobile-bearing PS-TKA (NexGen LPS Flex) and 12 subjects having a mobile-bearing UKA (Oxford UNI) were analyzed to determine their in vivo kinematic patterns under both weight bearing and non weight bearing. All implants were implanted by the same surgeon and were judged successful clinically with no pain and ligament laxity. The femoral and tibial components were overlaid onto the fluoroscopic images using a three-dimensional automated model-fitting technique to determine joint mobility. Results: The average range of motion was 124 degrees of flexion for the PS-TKA and 137 degrees of flexion for the UKA. Although subjects in this study exhibited variable motion pattern, the common is anterior movement in extension to 45 degrees of flexion and posterior movement in 60 degrees of flexion to full flexion. The average internal rotation of the tibia was 18 degrees in UKA and 6 degrees in PS-TKA at 100 degrees of flexion to full. Incidence of lateral condylar lift off greater than 2mm was 5 in the PS-TKA and 1 in the UKA. Discussion: A medial pivot kinematic pattern was observed in deep flexion in UKA. However in extension to 45 or 60 degrees of flexion, anterior condylar movement was observed in both groups. The motion pattern of UKA in 60 degree of flexion to full was close to the natural knee motion

Introduction. Selection of an optimum thickness of polyethylene insert in total knee arthroplasty (TKA) is important for the good stability and range of motion (ROM). The purpose of this study is to investigate the amount of change of ROM as the thickness of trial insert increase. Material and Method. The study included 86 patients with 115 knees undergoing TKA from October 2012 to February 2014. There were 17 men and 69 women with an average age of 75±8 (58–92) years. The implants posterior stabilized knee (Scorpio NRG, Stryker) was used and all prostheses were fixed with cement. The ROM was measured by the goniometer under the general anesthesia at the time of operation in increments of 1°. Preoperative flexion angle was measured by passively flexing the patient's hip 90 degrees and allowing the weight of the leg to flex the knee joint (Lee et al 1998). Extension angle was measured by holding the heel and raising the leg by another examiner. During TKA, flexion and extension angle was measured in a similar manner when each insert trial (8, 10, 12, and 15mm) was inserted. After the wound closure and removing the draping, ROM was measured again. Statistical analysis of range of motion was performed using a paired t-test to determine significance. Results. Preoperative extension angle was-11.8±7.5°and flexion angle was 125.4±14.9 °. postoperative extension angle after removing drapes was −5.0±3.4°and flexion angle was126.4±8.8°. Although extension angle was improved statistically (p<0.001), flexion angle was not improved. Intraoperative extension and flexion angle that were measured with the same thick insert trial as the polyethylene insert finally selected was −3.7±3.0°and 120.8±9.8°respectively. The thickness of polyethylene insert finally set was 8mm (28knees), 10mm (58knee), 12mm (24 knee), and 15mm (5knee). The amount of deficit in extension ROM by changing the trial inserts those were measured intraoperatively were 2.5±2.2° (n=112, 8 to 10mm, p<0.01), 3.2±2.8° (n=80, 10 to 12mm, p< 0.01), and 4.7±2.5° (n=15, 12 to 15mm, p<0.01). Flexion angle was 0.6±4.3° (8 to 10mm, n.s), 1.5±4.0° (10 to 12mm, p=0.002), 2.6±4.0° (12 to 15mm, p=0.025). Discussion. Although it is important to select a sufficient thick polyethylene insert to prevent postoperative instability, excessive thick polyethylene can decrease ROM especially extension. In many type of prosthesis, thickness of polyethylene insert differs every 2 mm is prepared. In the current study, if the thickness of polyethylene is increased 2mm (8 to10mm and 10 to 12mm) or 3mm (12 to15mm), extension and flexion angle was decreased 2.5–4.7°and 0.6–2.6°respectively

Binary Surface type knee prosthesis (bisurface knee) has successfully been utilized in total knee arthroplasty (TKA) in order to improve flexional motion, especially, deep flexion. Binary surface means that the knee prosthesis has two different bearing structures, that is, normal condylar surfaces and ball-socket structure. The ball and the socket are placed between the condylar surfaces of the femoral component and the tibial insert, respectively. Two different designs of bisurface knee have been proposed so far and only one model called KU has been utilized in clinical applications. The other model called CFK is still under development and characterized to have a post-cam structure to stabilize the knee motion. These bisurface knees are expected to attain deep flexional motion and therefore, it is important to understand their safety and durability at high flexion angles. In the present study, the finite element analysis (FEA) is conducted to characterize the mechanics of the bisurface knees under deep knee flexion. Risk assessment of the bisurface knees are then performed based on the FEA results. Detailed 3D-FEA models are constructed using CAD data and deep knee flexion corresponding to a squatting motion is reproduced by using spring models and proper boundary conditions. The spring models attached to the tibial component are used to express the mechanical effects of soft tissues. Internal rotational motion is also considered with the flexional motion. The femoral and the tibial components are assumed to be rigid and the tibial insert made of UHMWPE is an elastic-plastic solid having a nonlinear constitutive relation determined from experiments. The femoral component is rotated continuously from 0° to 135° to express the flexional motion and the tibial component is also rotated to express internal rotation. The equivalent stress of the condylar surface of the new CFK model is almost equivalent to that of the KU model during flexion from 0° to 90°, however, the stress values are different at the angles higher than 90°. At higher angles of flexion than 90°, the bearing surface of the KU consists of the condylar and the socket surfaces, while the bearing surface of the CFK consists of the socket surface only. Therefore, the CFK exhibits higher stress than the KU at these high angles. The ball-socket bearing system enables these bisurface knees to be adapted to deep flexional motion. The CFK is trying to achieve higher flexion angles than the KU by employing the modified ball-socket bearing structure, however, higher stress concentration on the socket surface of the CFK may hasten degradation of the tibial insert. It is also found that the stress concentration on the socket surfaces increase with increase of the internal rotation angle and therefore, the risk of damage of the tibial insert becomes higher with internal rotation. In summary, 3D dynamic FEA is utilized to make a risk assessment of the bisurface knees and the computational results suggest that the design of the ball-socket structure is one of the most important factors to determine the safety and durability of the knees

Introduction: Subject to recent literature citing a reduction in ankle range of motion predisposing to ankle fractures in children, we decided prospectively to analyse the passive range of motion in children presenting to our fracture clinic with simple distal radial metaphyseal fractures treated conservatively in cast. The range of motion was assessed by two observers, and measured using a goniometer in 80 patients. (42 radial fractures and 38 controls) The controls were recruited from children presenting with lower limb injuries and with no prior history of an upper limb injury or neuromuscular condition. The fractures were as a result of simple falls onto the outstretched hand with definite radiological and clinical findings. The range of motion in the contralateral limb was assessed. Both groups showed an equal distribution of dominant and non-dominant limbs. Results: Both groups were well matched with an average age of 10 and 10.3 years fracture group and control group respectively, and gender 55% male fracture group and 52.5% control group. The m injured group showed a passive range of motion of 1680, whereas the control group showed a higher range of motion of 1820, a difference of 140 (p< . 005 student t-test). A third blinded independent observer of 20 children assessed Intra and interobserver error, and no observer was noted to have higher or lower readings. Conclusion: Children with radial fractures have a lower passive range of motion of their wrists than Controls. This may contribute to the aetiology of wrist fractures in a paediatric population. An possible explanation may be as cited in original work that children who sustain fractures have less mobility around their joints due to reduced elasticity in their musculoskeletal framework. Simple passive stretching of fracture prone joints should therefore be advised

Purpose and background. Identifying features in nonspecific low back pain (NSLBP) subjects that distinguish them from controls, or for elucidating subgroups, has proved elusive. Yet these would be helpful to monitor progress, improve management, and understand the nature of the condition. Previous work using quantitative videofluoroscopy (QF) has indicated that the distribution of motion between lumbar intervertebral joints is more uneven in those with a history of NSLBP. However, there maybe other features of these complex motion patterns yet to be revealed. A multivariate analysis was therefore carried out to explore other possible differences. Methods and results. Intervertebral motion data of L2/3 to L4/5, from a previously published study was used. This examined 40 patients with NSLBP and 40 healthy controls, matched for gender, age and body mass index, who underwent passive recumbent QF in the coronal and sagittal planes. For each motion direction, principal components analysis was carried out and salient dimensions selected. Using a lower dimensional principal components (PC) representation, groups were compared using Hoteling's T test. Linear and quadratic discriminant analysis (LDA and QDA) was carried out using PC representations to examine group differences. The features most clearly distinguishing groups from the LDA was examined graphically. An analysis of the sensitivity of the results to the number of PC dimensions was carried out. The performance of the LDA and QDA classifiers were examined using leave-one-out cross-validation. Conclusions. Hotelling tests revealed significant differences between groups for right and left side-bending. This was confirmed by LDA and QDA. There was no clear difference in the performance of these classifiers and performance did not improve by including more than 4 PC dimensions. Visualisation of the LDA indicated that patients had relatively lower amplitude motion at L4/5, compensated by higher amplitude at L2/3/4. These results point to additional features of lumbar motion that differentiates NSLBP. No conflicts of interest. No funding obtained (however, the original study was funded by NIHR - CATCDRF09)

Introduction. The literature remains controversial on treatment of advanced stages of first metatarsophalangeal (MTP) arthritis and frequently favors arthrodesis. However, complications and suboptimal outcomes in active patients still remain with fusion of the first MTP joint. This study reports results of patients who underwent metallic resurfacing of the metatarsal side of the MTP joint. Materials and Methods. Twenty seven patients (31 implants) with stage II or III hallux rigidus underwent resurfacing with a fourth generation (screw fixation) contoured MTP implant and were willing to participate in a follow up study comparing pre- and postoperative radiographs, range of motion, AOFAS and SF-36 scores. The average age of these patients was 51 years (range 35-74) and the average follow up was 54 months (range 45-66). Results. The postoperative assessment demonstrated statistically significant improvements in range of motion, AOFAS, and SF-36 scores (P<0.05) when compared to baseline. The mean preoperative AOFAS scores improved from 51.5(range 35-74) to 94.1 (range 82-100). The mean preoperative active range of motion improved from 19.7 degrees (range 5-50) to 47.9 degrees (range 25-75). The mean preoperative passive range of motion improved from 28.0 degrees (range 10-60) to 66.3 degrees (range 40-90). The mean SF-36 score improved from 71.2 (range 60.6-80.0) to 88.2 (range 69.6-99.1), physical health sub scores improved from 66.8 (range 40-87) to 90.1 (range 70-98). The average time for return to work was 7 days (range 3-20). There was one implant revision due to phalangeal disease progression. All other patients were satisfied and willing to have the procedure performed again. Conclusion. Current 4 and 5 year results are very promising. Preservation of joint motion, alleviation of pain and functional improvement data are very encouraging. Because minimal joint resection is performed, conversion to arthrodesis or other salvage procedures is relatively simple if further intervention is necessary

Digital image correlation (DIC) is rapidly increasing in popularity in biomechanical studies of the musculoskeletal system. DIC allows the re-construction of full field displacement and/or strain maps of the surface of an object. DIC systems typically consist of two cameras focussing on the same region of interest. This constrains the angle between the cameras to be relatively narrow when studying specimens characterised by complex geometrical features, giving rise to concerns on the accuracy of the out of plane estimates of movement. The aim of this research was to compare the movement profiles of bony segments measured by DIC and by an optoelectronic motion capture system. Five porcine cervical spine segments (C2-C6) were obtained from the local butcher. These were stripped of all anterior soft tissues while the posterior structures were left intact. A speckle pattern was applied to the anterior aspect of the specimens, while custom made infrared clusters were rigidly attached to the 3 middle vertebral bodies (C3-C5). The specimens were mounted in a custom made impact rig which fully constrained C6 but allowed C2 to translate in the axial direction of the segment. Images were acquired at 4kHz, both for the DIC (Photron Europe Ltd, UK) and motion capture cameras (Qualisys Oqus 400, Sweden). The in-plane and out of plane displacements of each of the VBs were plotted as a function of time and the similarity between the curves thus obtained was analysed using the SPM1D technique which allowed a comparison to be made in terms of t-statistics. No statistical differences were found between the two techniques in all axis of movement, however the out of plane movements were characterised by higher variance which is attributed to the uncertainty arising from the near parallel positioning of the cameras in the experimental set-up

Outcomes for guided motion primary total knee arthroplasty (TKA) in obese patients are unknown. 1,684 consecutive patients underwent 2,059 primary TKAs with a second-generation guided motion implant between 2011–2017 at three European and seven US sites. Of 2,003 (97.3%) TKAs in 1,644 patients with BMI data: average age 64.5 years; 58.4% females; average BMI 32.5 kg/m2; 13.4% had BMI ≥ 40 kg/m2. Subjects with BMI ≥ 40 kg/m2 had longest length of hospital stay (LOS) at European sites; LOS similar at US sites. Subjects with BMI ≥ 40 kg/m2 (P=0.0349) had longest surgery duration. BMI ≥ 40 kg/m2 had more re-hospitalizations or post-TKA reoperations than BMI < 40 kg/m2 (12.7% and 9.2% at five-year post-TKA, P<0.0495). Surgery duration and long-term complication rates are higher in patients with BMI ≥ 40 kg/m2, but device revision risk is not elevated

Background. Patient satisfaction after total knee arthroplasty (TKA) has been lower than after a similar procedure, total hip arthroplasty. Poor subjective outcomes after TKA may be partially explained by abnormal kinematics patterns after TKA. The purpose of this study was to analyse rotational kinematics patterns in knees that had undergone posterior stabilized (PS)-TKA, and to clarify the relationships between rotational kinematics patterns and patient satisfaction, as well as between rotational kinematics patterns and knee function. Materials & Methods. A total of 49 osteoarthritis knees after primary PS-TKA (NexGen LPS-Flex fixed bearing knee system) were included in this study; deformed valgus, severe flexion contractures, and highly unstable knees were excluded. We used a computer navigation system and measured knee kinematics after each surgery was completed. A single investigator gently applied a manual range of motion from full extension to flexion. The angle of the internal rotation of the tibia was measured automatically at 0º, 30º, 45º, 60º, and 90º, along with maximum extension and flexion. We categorized the post-operative rotational kinematics patterns for individual cases, focusing on the initial knee flexion from 0–30º. Type A corresponded to an increased internal rotation angle of the tibia during the initial knee flexion (screw home-like movement). Type B corresponded to an increased external or an unchanged rotation angle of the tibia. We examined the range of motion (ROM) at 6 months after surgery and assessed the 2011 Knee Society Score (2011 KSS) at ≥1 year following surgery. Statistical analysis. The difference between the two groups was compared using a Wilcoxon rank sum test. Analyses were performed with JMP statistical software v8.0 (SAS Institute). A p-value of <0.05 was regarded as significant. Results. The tibia exhibited an average of 5º of internal rotation at initial knee flexion. The type A kinematics pattern achieved a better ROM and functional activity score (2011 KSS) than the type B kinematics pattern. Discussion. Modern TKA implants have been designed to reproduce normal knee kinematics to achieve better patient satisfaction and knee function. However, few reports have described the relationship between the rotational kinematics patterns at initial knee flexion and patient satisfaction. In our study, the type A postoperative rotational kinematics pattern (screw home-like movement) had better ROM and functional activity score than the type B kinematics pattern. The movement toward the internal rotation of the tibia during initial knee flexion might be important in achieving better clinical results after PS-TKA

Interventional MRI provides a novel non-invasive method of in-vivo weight-bearing analysis of the talo-calcaneal joint. Six healthy males (mean 28.8 years) underwent static right foot weight bearing MRI imaging at 0o, 15o inversion, and eversion. Using known radiological markers the motion of the talus and calcaneum were analysed. The calcaneum externally rotates, plantar-flexes and angulates into varus. The talus shows greater plantarflexion with similar varus angulation, with variable axial rotation. Relative talo-calcaneal motion thus involves, 6o relative talar internal rotation, 3.2o flexion and no motion in the frontal plane. Concurrently the talus moves laterally on the calcaneum, by 6.5mm, with variable translations in other planes. The calcaneum plantar-flexes, undergoes valgus angulation, and shows variable rotation in the axial plane. The talus plantar-flexes less, externally rotates, and shifts into varus. Relative motion in the axial and saggital plane reverses rotations seen during inversion. The 8o of relative valgus talo-calcaneal angulation is achieved through considerable varus angulation of the talus, in a direction opposite to the input motion. This phenomenon has not been previously reported. From coronal MRI data, comparative talo-calcaneal motion in inversion is prevented by high bony congruity, whereas during eversion, the taut posterior tibio-talar ligament appears to prevent talar valgus angulation. We have demonstrated that Interventional MRI scanning is a valuable tool in analysing the weight-bearing motion of the talo-calcaneal joint, whilst approaching the diagnostic accuracy of stereophotogammetry. We have also demonstrated consistent unexpected talar motion in the frontal plane. Talo-calcaneal motion is highly complex involving simultaneous rotation and translation, and hence calculations of instantaneous axes of rotation cannot effectively describe talo-calca-neal motion. We would suggest that relating individual and relative motion of the talus / calcaneum better describes subtalar kinematics

INTRODUCTION. In patients with neural disorders such as cerebral palsy, three-dimensional marker-based motion analysis has evolved to become a well standardized procedure with a large impact on the clinical decision-making process. On the other hand, in knee arthroplasty research, motion analysis has been little used as a standard tool for objective evaluation of knee joint function. Furthermore, in the available literature, applied methodologies are diverse, resulting in inconsistent findings [1]. Therefore we developed and evaluated a new motion analysis framework to enable standardized quantitative assessment of knee joint function. MATERIALS AND METHODS. The proposed framework integrates a custom-defined motion analysis protocol with associated reference database and a standardized post-processing step including statistical analysis. Kinematics are collected using a custom-made marker set defined by merging two existing protocols and combine them with a knee alignment device. Following a standing trial, a star-arc hip motion pattern and a set of knee flexion/extension cycles allowing functional, subject-specific calibration of the underlying kinematic model, marker trajectories are acquired for three trials of a set of twelve motor tasks: walking, walking with crossover turn, walking with sidestep turn, stair ascent, stair descent, stair descent with crossover turn, stair descent with sidestep turn, trunk rotations, chair rise, mild squat, deep squat and lunge. This specific set of motor tasks was selected to cover as much as possible common daily life activities. Furthermore, some of these induce greater motion at the knee joint, thus improving the measurement-to-error ratio. Kinetics are acquired by integrating two forceplates in the walkway. Bilateral muscle activity of 8 major muscles is monitored with a 16 channel wireless electromyography (EMG) system. Finally, custom-built software with an associated graphical user interface was created for automated and flexible analysis of gait lab data, including repeatability analysis, analysis of specific kinematic, kinetic and spatiotemporal parameters and statistical comparisons. RESULTS. Following ethical approval and informed consent, the proposed framework was successfully applied in a control group of 80 normal subjects within a wide age-range (age: 54.5Y±19.1; BMI: 25.5±4.0; 40M/40F; 60 Caucasian, 20 Asian) thus constructing the reference database for control. Moreover, the same framework was applied successfully in a randomly selected group of 10 patients with a bi-compartmental knee replacement (BKR) (age: 67.3Y±5.3; BMI: 29.7±3.1; time post-op: 1.65Y±0.4; 2M/8F Caucasian). Comparison between these patients and age-matched controls demonstrates that, for a large range of motor tasks, knee joint kinematics after BKR are as much consistent with the healthy controls (coefficient of multiple correlation (CMC) =0.49) as the consistency within a group of controls or BKR-subjects individually (CMC=0.52). Nevertheless, also significant differences (p<0.0167) were identified which are indicative for retention of pre-operative motion patterns and/or remaining compensations. CONCLUSION. The proposed framework allows in-vivo evaluation of knee joint performance in a standardized, objective and non-invasive way. It is applicable in both healthy subjects and knee replacement patients and is shown to be sufficiently sensitive to detect even relatively small differences between the two populations

There are several concerns about the current simulators for TKA. First, the knee is flexed in a “passive way” under the condition of applying constant muscular tension forces. Second, the effects of hip joint motion are not taken into account. Thirdly, the external load for example, upper body weight is not applied in a natural way. Finally, few simulators are capable of knee flexion greater than about 100°. To this end, we have developed a novel knee simulator system that reproduces the active and natural knee motion to evaluate kinematics and joint forces of TKA. Our simulator system has the following advantages and innovative features. First, it is driven directly by muscles' tension forces, and the knee is capable of active flexion. Secondly, a hip joint is incorporated into it and the lower limb motion is achieved in a synergistic way between the hip and knee joints. Thirdly, it is capable of complete deep knee flexion up to 180°. Figure 1 shows the structure of the system. Both the hip and knee joints are moved by the tension forces of four wires that simulate the functions of the mono-articular muscles ((1), (3)) and the bi-articular muscles ((2), (4)) by means of a multiple pulley system (Fig 2). The femoral and tibial components of TKA are secured in the distal end of the upper link (thigh) and the proximal end of the lower link (shank) respectively. The ankle assembly has three sets of rotary bearings whose axes intersect at a fixed point, the center of the ankle, allowing spherical movement of the tibia about the ankle center. Springs were stretched around the ankle center to substitute the muscles around the ankle. Weights I and II are counterweights so as to duplicate the weights of the human upper body, thigh and shank respectively. The wires are pulled to produce the hip and knee motions. The linear bearings running along vertical rods also prevent the system from collapsing. In the experiment, a custom-designed posterior stabilized type TKA was attached to the simulator system for evaluation. The system was operated so as to reproduce the sit-to-stand features in a quasi-static manner in order to study the kinematics of TKA. Beyond 130°, the knee proceeded to flex passively because of upper body weight. Conspicuous internal/external rotation or valgus/varus motion of the tibia relative to the femur was not observed as the knee flexed. When our simulator system was driven in a quasi-static manner, it was able to measure the kinematics of TKA however, when the system was driven in a dynamic manner, it oscillated because the springs around the ankle were not stiff enough to hold the inverted pendulum-like system upright and the ratios of the tension force exerted by the four wires simulating muscles could not be determined appropriately

Introduction. Hip osteoarthritis (OA) results in reduced hip range of motion and contracture, affecting sitting and standing posture. Spinal pathology such as fusion or deformity may alter the ability to compensate for reduced joint mobility in sitting and standing postures. The effects of postural spinal alignment change between sitting and standing is not well understood. Methods. A retrospective radiographic review was performed at a single academic institution of patients with sitting and standing full-body radiographs between 2012 and 2017. Patients were excluded if they had transitional lumbosacral anatomy, prior spinal fusion or hip prosthesis. Hip OA severity was graded by the Kellgren-Lawrence grades and divided into two groups: low-grade OA (LOA; grade 0–2) and severe OA (SOA; grade 3–4). Spinopelvic parameters (Pelvic Incidence (PI), Pelvic Tilt (PT), Lumbar Lordosis (LL), and PI-LL), Thoracic Kyphosis (TK; T4-T12), Global spinal alignment (SVA and T1-Pelvic Angle; TPA; T10-L2) as well as proximal femoral shaft angle (PFSA: as measured from the vertical), and hip flexion (difference between change in PT and change in PFSA) were also measured. Changes in sit-stand radiographic parameters were compared between the LOA and SOA groups with unpaired t-test. Results. 548 patients were identified with sit-stand radiographs, of which there were 311 patients with LOA & 237 with SOA. After propensity score matching for Age, BMI, and PI, 183 LOA & 183 SOA patients were analyzed. Standing alignment analysis demonstrated that SOA patients had greater SVA (31.1 ± 36.68 vs 21.7 ± 38.83, p=0.02), and lower TK (−36.21 ± 11.98 vs −41.09 ± 11.47, p<0.001). SOA patients had lower PT, greater PI-LL, lower LL, lower T10-L2, and lower TPA (p>0.05). PFSA (9.09 5.19 vs 7.41 4.48, p<0.001) was significantly different compared to LOA while SOA KA was not significantly different compared to LOA. Sitting alignment analysis demonstrated that SOA patients had higher PT (29.69 ± 15.65 vs 23.32 ± 12.12, p<0.001), higher PI-LL (21.64 ±17.86 vs 12.44 ±14.84 p<0.001), lower LL (31.67 ± 16.40 vs 41.58 ± 14.73, p<0.001), lower TK (−33.22 ± 15.76 vs −38.57 ± 13.01, p=0.01), greater TPA (27.91 ± 14.7 vs 22.55 ± 11.38 p=0.01). TK, SVA, and PFSA were not significantly different compared to LOA. SOA and LOA groups demonstrated differences in standing and sitting spinopelvic alignment for all global and regional parameters except PI. When examining the postural changes from standing to sitting, there was less hip ROM in SOA than LOA (71.45 ± 18.55 vs 81.64 ± 12.57, p<0.001). As a result, SOA patients had more change in PT (15.24 ± 16.32 vs 7.28 ± 10.19, p<0.001), PI-LL (20.62 ± 17.25 vs 13.74 ± 11.16, p<0.001), LL (−21.37 ± 15.55 vs −13.09 ± 12.34, p<0.001), and T10-L2 (−4.94 ± 7.45 vs −1.08 ± 5.19, p<0.001) to compensate. SOA had a greater improvement in TPA (15.06 vs 9.59, p<0.001), and less change in PFSA (86.65 vs 88.81, p<0.001) compared to LOA. Conclusions. Spinopelvic compensatory mechanisms are adapted for reduced joint mobility associated with hip OA in standing and sitting

Clinical investigations show that the cervical spine presents wide inter-individual variability, where its motion patterns and load sharing strongly depend on the anatomy. The magnitude and scope of cervical diseases, including disc degeneration, stenosis, and spondylolisthesis, constitute serious health and socioeconomic challenges that continue to increase along with the world”s growing aging population. Although complex exact finite element (FE) modeling is feasible and reliable for biomechanical studies, its clinical application has been limited as it is time-consuming and constrained to the input geometry, typically based on one or few subjects. The objective of this study was twofold: first to develop a validated parametric subject-specific FE model that automatically updates the geometry of the lower cervical spine based on different individuals; and second to investigate the motion patterns and biomechanics associated with typical cervical spine diseases. Six healthy volunteers participated in this study upon informed consent. 26 parameters were identified and measured for each vertebra in the lower cervical spine from Lateral and AP radiographs in neutral, flexion and extension viewpoints in the standing position. The lower cervical FE model was developed including the typical vertebrae (C3-C7), intervertebral discs, facet joints, and ligaments using ANSYS (PA, USA). In order to validate the FE model, the bottom surface of C7 was fixed, and a 73.6N preload together with a 1.8 N.m pure moment were input into the model in both flexion and extension. The results were compared to experimental studies from literature. Disc degeneration disease (DDD) was used as an example, where the geometry of C5-C6 disc was changed in the model to simulate 3 different grades of disc degeneration (mimicking grades 1 to 3), and the resulting biomechanical responses were evaluated. The average ranges of motion (ROM) were found to be 4.84 (±0.73) degrees and 5.36 (±0.68) degrees for flexion and extension for C5-C6 functional unit, respectively, in alignment with literature. The total ROM of the model with disc generation grades 2 and 3 was found to have decreased significantly as compared to the intact model. In contrast, the axial stresses on the degenerated discs were significantly higher than the intact discs for all 3 degeneration grades. Our preliminary results show that this novel validated subject-specific FE model provides a potential valuable tool for noninvasive time and cost effective analyses of cervical spine biomechanical (kinematic and kinetic) changes associated with various diseases. The model also provides an opportunity for clinicians to use quantitative data towards subject-specific informed therapy and surgical planning. Ongoing and future work includes expanding the studied population to investigate individuals with different cervical spine afflictions

Background: Interventional MRI provides a novel non-invasive method of in-vivo weight-bearing analysis of the subtalar joint. Preceding in-vivo experimentation with stereophotogammetry of volunteers embedded with tantalum beads has produced valuable data on relative talo-calcaneal motion (Lundberg et al. 1989). However the independent motion of each bone remains unanswered. Materials and Methods: Six healthy males (mean 28.8 years), with no previous foot pathology, underwent static right foot weight bearing MRI imaging at 0°, 15° inversion, and 15° eversion. Using identifiable radiological markers the absolute and relative rotational and translational motion of the talus and calcaneum were analysed. Results and Discussion:Inversion: The calcaneum externally rotates, plantar-flexes and angulates into varus. The talus shows greater plantar-flexion with similar varus angulation, with variable axial rotation. Relative talo-calcaneal motion thus involves, 6° relative talar internal rotation, 3.2° flexion and no motion in the frontal plane. Concurrently the talus moves laterally on the calcaneum, by 6.5mm, with variable translations in other planes. This results in posterior facet gapping and riding up of the talus at its posterolateral prominence. Eversion: The calcaneum plantar-flexes, undergoes valgus angulation, and shows variable rotation in the axial plane. The talus plantar-flexes less, externally rotates, and shifts into varus. Relative motion in the axial plane reverses rotations seen during inversion (2.5° talar external rotation). The 8° of relative valgus talo-calcaneal angulation is achieved consistently through considerable varus angulation of the talus, in a direction opposite to the input motion. This phenomenon has not been previously reported. From coronal MRI data, comparative talo-calcaneal motion in inversion is prevented by high bony congruity, whereas during eversion, the taut posterior tibio-talar ligament prevents talar valgus angulation. Conclusion: We have demonstrated that Interventional MRI scanning is a valuable tool to analysing the weight bearing motion of the talo-calcaneal joint, whilst approaching the diagnostic accuracy of stereophoto-gammetry. We have also demonstrated consistent unexpected talar motion in the frontal plane. Talo-calcaneal motion is highly complex involving simultaneous rotation and translation, and hence calculations of instantaneous axes of rotation cannot effectively describe talo-calcaneal motion. We would suggest that relating individual and relative motion of the talus / calcaneum better describes subtalar kinematics

INTRODUCTION. Patellofemoral compilcations are among the most frequently observed adverse events after total knee arthroplasty. The posterior location with Femoral component of conventional TKA in AP alignment cause paradoxical movement, but, guide motion TKA (Journey.2.BCS) with anterior post-cam remain a correct AP alignment. The purpose of this study was to investigate patellofemoral (PF) contact stress between Bi-Cruciate Substituting TKA (Journey.2.BCS) and CR TKA (Journey.CR). METHODS. We evaluated 22 knees with medial compartment osteoarthritis who underwent. Simultaneous bilateral TKA. The prospective randomized study was to measure intraoperative PF contact stress by a patellofemoral sensor (Kyowa Co., Ltd., Tokyo, Japan) comparing the identical Bi-Cruciate Substituting or CR Journey.2 total knee prostheses implanted bilaterally in the same patient. RESULTS. The PF contact stress showed significantly greater at CR TKA than at BCS TKA in 120 and 140 degrees of flextion (p=0.04, p=0.018). and showed no significant correlations with postoperative flextion angles. DISCUSSION AND CONCLUSION. In guide motion TKA, CR prosthesis increases PF contact stress than Bi-Cruciate Substituting prosthesis. The femoral rollback with medial pivot motion at CR TKA decreases more as the BCS TKA. Increased PF contact stress in guided motion TKA is not necessarily decrease postoperative flextion angle