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

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

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

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

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. 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

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

The glenohumeral joint is an important joint with large mobility of the human upper extremity. In shoulder arthroplasty patients often has an unsatisfactory outcome. In order to understand the biomechanical complexity of the shoulder, a novel computer controlled experimental shoulder simulator with an innovative muscle control were constructed. The main component of the simulator includes the active pneumatic muscles to replicate the deltoid and the rotator-cuff function and two springs as passive muscle. The aim of this study is to evaluate the impact of a variation of shoulder joint geometries on shoulder biomechanics in the basis of motion analysis. The radius of the glenoid cavity varied from 28–33mm with 2.5mm increment while the radius the humeral head are varied from 20.1–25.1 with 2.5mm increment. The “teach-in” function of the simulator allows an operator to assign the movement to the simulator where the lengths of the pneumatic muscles are recorded. Then the simulator repeats the assigned movement according to the recorded muscles length. The daily living activities includes abduction/adduction, internal/external rotation with adducted arm, and circumduction. The results show promising repeatability of the simulator with minor deviation. However, damage on the surface of the humeral head has been found which should be further studied for both shoulder behavior investigation and the shoulder simulator optimisation. Therefore, this study is a decent initial study toward the verification of the simulator and lead to a better understanding of shoulder biomechanical behavior to cope with the clinical problems in the future

Introduction: Clinical outcome scores such as the DASH shoulder score suffer from subjectivity, a ceiling effect and pain dominance masking functional changes which shall be assessable to address rising patient demands and improve the clinical validation of modern therapeutic improvements. Lab based motion analysis may provide such data but it is too costly, time consuming and complex for routine clinical follow-up. Inertia sensor based motion analysis (IMA) can produce objective movement parameters while being fast, cheap and easy to operate. In this study, a simple and clinical feasible inertia sensor based motion analysis (IMA) shoulder test is defined and tested for its. reliability,. diagnostic power to recognize pathological movement and. validity against gold standard clinical scores. Methods: An inertia sensor (41x63x24mm, 39g) comprising 3D accelerometers (±5g) and 3D gyroscopes (±300°/sec) was taped onto the humerus in a standardised position. Healthy subjects (n=100, 40.6 ±15.7yrs) and 50 patients (55.6 ±12.7yrs, m/f 17/33) with confirmed unilateral shoulder pathology (39 subacromial impingement, 11 other) were measured. Two motion tasks (hand-behind-head, hand-to-back) were performed on both shoulders. Using automated algorithms, a simple motion parameter was calculated by adding the peak-to-peak angular rates per axis. The relative asymmetry between both shoulder sides was scored (healthy control within subject). Patients were also assessed using the DASH score and the Simple Shoulder Test (SST). Results: The test produced high intra- (r2=0.90) and inter-observer reliability (r2=0.83). Asymmetry was > 3 times higher in patients (36.3%) than healthy controls (9.6%, p< 0.001). Using a threshold (> 16% asymmetry) healthy and pathological subjects could be distinguished with high diagnostic sensitivity (98.0%) and specificity (81.0%). The non-affected shoulders of the patient group did not differ from the shoulder of the healthy group (p=0.18). Sub-group analysis comparing the 30 best performing healthy to the 10 highest asymmetry pathological shoulders also revealed sign. lower range of motion, shorter motion path and longer cycle times (p< 0.01). Visual signal analysis exposed specific motion patterns (e.g. healthy: overshooting at point of task achievement, pathological: drift or tremble at rest position). IMA asymmetry was only weakly correlated with DASH or SST (r2< 0.25). Discussion: The IMA shoulder test and asymmetry score showed high reliability and diagnostic power meeting or exceeding common clinical scores. The fast assessment (t< 60s) of a simple motion tasks makes it suitable for routine clinical follow-up to supplement classic scores. Weak correlations with DASH and SST show that the test adds an objective functional dimension to outcome assessment

Spinal Biomechanics Lab, Baylor College of Medicine, Houston, Texas, USA. Documenting the patterns and frequency of collapse in non-operatively managed spine fractures, using a motion analysis software. Retrospective analysis of prospective case series. 105 patients with thoracic or lumbar fractures, were neurologically intact, and treated non-operatively for the ‘stable’ injury at our unit between June 2003 and May 2006. The mean age of the cohort was 46.9 yrs. Serial radiographs (mean 4 radiographs/patient; range 2 – 9) were analysed using motion analysis software for collapse at the fracture site. We defined collapse as a reduction of anterior or posterior vertebral body height greater than 15% of the endplate AP width, or a change in the angle between the inferior and superior endplates > 5°. The changes were assessed on serial radiographs performed at a mean of 5.6 mo (95% CI 4.1 – 7.1 mo) after the initial injury. 11% showed anterior collapse, 7.6% had posterior collapse, 14% had collapse apparent as vertebral body wedging, and 17% had any form of collapse. ODI scores were obtained in 35 patients at the time of the last available radiograph. There were no significant differences in ODI scores that could be associated with the presence of any form of collapse (p > 0.8 for anterior collapse; and p = 0.18 for posterior collapse). This pilot study with the motion analysis software demonstrates that some fractures are more likely to collapse with time. We hope to carry this work forward by way of a prospective study with a control on other variables that are likely to affect the pattern and probability of post-fracture collapse, including age, bone density, vertebral level, activity level, fracture type

The cervical spine exhibits the greatest range of motion amongst the spinal segments due to its tri-planar components of movement. As a result, measurement of movements has proved difficult. A variety of methods have been used in an attempt to measure these movements but none have provided satisfactory triplanar data. This paper uses the Zebris ultrasonic 3-D motion analysis system to measure flexion, extension, range of lateral bending and range of axial rotation in five similar male and five similar female subjects with no history of neck injuries. The subjects were tested unrestrained and in soft and hard collars, as well as in Philadelphia, Miami J and Minerva orthoses. Results show that the Minerva is the most stable construct for restriction of movement in all planes in both groups (p< 0.001 vs. all groups (p=0.01 vs. Philadelphia in female extension), ANOVA). In the male group, the standard hard collar provides the second best resistance to flexion, lateral bending and axial rotation. The female group showed no one orthosis in second place overall. Looking at these results allows ranking of the measured orthoses in order of their three-dimensional stability. Furthermore, they validate the Zebris as a reliable and safe method of measurement of the complex movements of the cervical spine with low intersubject variability. In conclusion, this paper, for the first time presents reproducible data incorporating the composite triplanar movements of the cervical spine thus allowing comparative analysis of the three-dimensional construct stability of the studied orthoses. In addition, these results validate the use of the Zebris system for measurement of cervical spine motion

We have developed a novel system of 4-dimensional motion analysis after total hip arthroplasty (THA) that can aid in preventing dislocation by assessing safe range of motion for patients in several daily activities. This system uses skeletal structure data from CT and motion capture data from an infrared position sensor. A 3-D model reconstructed from CT data is combined with the motion capture data. Using this system, we analyzed hip motion when getting up from and sitting down in a chair or picking up an object while sitting in a chair in 17 patients (26 hips) who underwent THA. To assess the accuracy of this system’s measurements, open MRI was used to evaluate positions of skin markers against bones in 5 healthy volunteers in various postures. No impingement between bones and/or implants was found in any subjects during any activities. However, mean angle at the point of maximum hip flexion was different for each patient. The open MRI results indicated that average error in hip angle of the present system was within 5 degrees for each static posture. The functional position of the pelvis during daily activities must be taken into account when assessing the real risk of dislocation. The present system enables dynamic analysis involving not only alignment of components and bones of each patient, but also individual differences in characteristics of daily motions. Further investigation using this system can help determine safe ranges of motion for preventing hip dislocation, improving the accuracy of individualized guidance for patients regarding postoperative activities

Hypothesis: Athletes significantly alter their lumbar spinal motion when performing squat lifting at heavy weights. This altered motion effects a change in pressure in the posterior annulus of lumbar discs. Study Design:. 3-D motion analysis of lumbar spinal motion in athletes, during squat weight lifting. Pressure measurement of the posterior annulus following the motion analysis study. Methods: 48 athletes performed 6 lifts at 40% maximum, 4 lifts at 60% max and 2 lifts at 80% max. 3-D motion analysis system, measured lumbar spine motion. Exercise performed as a ‘free’ squat and repeated with a weight lifting support belt. 4 cadaveric sheep spinal motion segments mounted in purpose built jig, replicating angulation seen in the in vivo motion study. These samples were then fixed to a tension/compression loading frame, replicating the forces seen in the in vivo study. Pressure measurement was achieved using a Flexiforce single element force sensor strip, positioned at the posterior annulus. Posterior annulus pressure was measured during axial compression and on compression with the specimen fixed at 3° of extension. Results:. Significant decrease (p< 0.05) in flexion in all groups when lifting at 40% max was compared with lifting at 60% and 80% of max. Flexion from calibrated zero point ranged from 24.7° (40% group), to 6.8° (80% group). A progressively significant increase (p< 0.05) seen in extension in groups studied when lifting at 40% max was compared with lifting at 60% and 80% max lift. Extension from a calibrated zero point ranged from − 1.5° (40% group), to − 20.3° (80% group). No statistically significant difference found between motion seen when performing the exercise as a ‘free’ squat or when lifting using a support belt in any group studied. Initial uniform rise in measured pressure readings to a pressure of 350–400N, in the axially loaded and extension loaded specimens. Pressure experienced by the axially loaded group then gradually dropped below the pressure exerted by the loading frame, while the pressure experienced in the posterior annulus of the extension loaded specimens progressively increased. Comparing axially loaded specimens with specimens loaded in extension, there was an average increase in pressure of 36.4% in the posterior annulus, when the spine was loaded in 3° of extension at a pressure equivalent to the 80% lift in the in vivo motion study, in comparison to axial loading. Conclusions: Squat weight lifting at heavier weights, causes athletes to lift at a progressively greater degree of extension. The use of a weight lifting support belt does not significantly alter spinal motion during lifting. The increased extension at heavier weights results in a stress concentration in the posterior annulus of lumbar discs

Introduction: In clinical orthopaedics questionnaire based outcome scores such as the DASH shoulder score suffer from a ceiling effect, subjectivity and the dominance of pain perception over functional capacity. As a result it has becomes increasingly difficult to clinically validate medical innovations in therapy or implants and to account for rising patient demands. Thus, objective functional information needs to be added to routine clinical assessment. Motion analysis with opto-electronic systems, force plates or EMG is a powerful research tool but lab-based, too expensive and time consuming for routine clinical use. Inertia sensor based motion analysis (IMA) can produce objective motion parameters while being faster, cheaper and easier to operate. In this study a simple IMA shoulder test is defined and. its reliability tested,. its diagnostic power to distinguish healthy from pathological shoulders is measured and. it is validated against gold standard clinical scores. Methods: An inertia sensor (41x63x24mm3, 39g) comprising a triaxial accelerometer (±5g) and a triaxial gyroscope (±300°/sec) was taped onto the humerus in a standardised position. One-hundred healthy subjects without shoulder complaints (40.6 ±15.7yrs) and 40 patients (55.4 ±12.7yrs) with confirmed unilateral shoulder pathology (29 subacromial impingement, 9 rotator cuff pathology, 2 other) were measured. Two motion tasks (‘hand behind the head’ and ‘hand to the back’) based on the Simple Shoulder Test (SST) were performed on both shoulders (three repetitions at self selected speed). Motion parameters were calculated as the surface area described by combing two angular rate signals of independent axes (ARS) or by combing the angular rate and the acceleration of a single axis (COMP score). The relative asymmetry between two sides was scored. Results: The test produced high intra-(r2≥0.88) and inter-observer reliability (r2≥0.82). Healthy subjects scored a mean asymmetry of 9.6% (ARS) and 14.6% (Comp). Patients with shoulder complaints showed > 3× higher asymmetry (ARS: 34.1%, Comp: 42.7%) than the healthy controls (p< 0.01). Using thresholds (ARS: 16%, Comp 27%) healthy and pathological subjects could be distinguished with high diagnostic sensitivity (e.g. ARS: 97.5% [CI: 85.3–99.9%]) and specificity (e.g. COMP: 85.5% [CI: 76.1–91.1%]). Both asymmetry scores were strongly intercorrelated (r2=0.76) as were the clinical scores (r2=0.62, DASH-SST). Asymmetry and clinical scores were hardly correlated (r2< 0.14). Discussion: The IMA shoulder test and asymmetry scores showed high reliability meeting or exceeding common clinical scores. With a fast assessment of a simple ADL tasks (test duration < 60s) it was possible to provide diagnostic power at clinically usable level making routine clinical application feasible even by nonspecialist personnel. Weak correlations with the clinical scores show that the new test adds an objective functional dimension to outcome assessment which may have the potential to differentiate new treatments or implants required to trigger new therapeutic innovation cycles. Similar motion tests and parameters could also serve lower extremity outcome assessment

The aim of this study was to use motion analysis to study a surgeon’s learning curve for an arthroscopic Bankart repair on a training model in a skills laboratory. Six fellowship trained lower limb surgeons unfamiliar with advanced shoulder arthroscopy performed an arthroscopic Bankart repair on an ALEX shoulder model. Standardised training was given and then an electromagnetic tracking system used to objectively assess hand movements, distance travelled by hands and time taken while the surgeons performed the technique. The arthroscopic repair was repeated three times on four consecutive occasions by each surgeon giving a total of 72 repair episodes. Analysis revealed improvement of all outcome parameters with less hand movements, less distance travelled and less time to complete the task. This study objectively demonstrates a learning curve for arthroscopic Bankart suture in a skills laboratory. It indicates the potential benefits of practicing aspects of arthroscopic techniques in a skills centre on appropriately selected models

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

Modern orthopaedics increasingly demands objective functional outcome assessment beyond classic scores and tests suffering from subjectivity, pain dominance and ceiling effects. Inertia based motion analysis (IMA) is a simple method and validated for gait in knee arthroplasty patients. This study investigates whether IMA assessed stair climbing can distinguish between healthy and pathological subjects and is able to diagnose a meniscal tear (MT). Following standard physical examination (McMurray, rotation pain), 37 patients (18–72yrs) received arthroscopy suspecting a meniscal tear resulting from trauma, degeneration or both. Arthroscopy identified the presence or absence of MT and the osteoarthritis level (Outerbridge). Prior to arthroscopy, the ascending and descending five stairs twice at preferred speed and without the use of handrails was measured using a triaxial accelerometer (62×41×18mm; m=53g; f=100Hz) taped to the sacrum. Based on peak detection algorithms, temporal motion parameters were derived such as step time up and down (Tup, Tdown), the difference between step time up and down (Tup-down), step irregularity (step time difference of subsequent steps) and step asymmetry (step time difference between affected and non-affected leg). Patients were compared to a control group of 100 healthy subjects (17–81yrs) without any known orthopaedic pathology. Using the results of arthroscopy, test sensitivity and specificity for differentiating healthy and pathologic subjects and for diagnosing MT were calculated based on threshold values. Sensitivity and specificity for detecting pathological motion was 0.68 (CI 0.50–0.81) and 0.92 for the most sensitive parameter (Tdown). Sensitivity and specificity to detect MT was 0.74 and 0.25 percent overall compared to 0.53 and 0.50 for the McMurray. Sensitivity increased to 1.00 when MT was combined with a chondropathy scale III or IV (McMurray 0.33). IMA assessed stair climbing can distinguish healthy and pathological subjects and detect the presence of MT with better sensitivity than classic scores especially when combined with severe chondropathy. IMA is a simple and fast clinical outcome measure suitable for routine follow-up and may support the diagnosis of meniscal tears prior to arthroscopy

While numerous studies have examined dislocation caused by basic everyday movements, no objective studies have investigated body positions to minimize risk of dislocation during intercourse. We therefore used a four-dimensional motion analysis system to assess sexual activities in patients who had undergone total hip arthroplasty (THA), to identify body positions displaying less risk of dislocation. Five body-surface infrared sensors were placed on five healthy female volunteers, and maximum hip joint angle was measured. Subjects were asked to take the following three body positions: supine (missionary); top (woman on top); and kneeling (doggy-style). Angle data obtained using body surface markers were combined with three-dimensional skeletal models extracted using CT images obtained from the 24 joints of 16 patients who had undergone THA, to ascertain angles at which collision with the artificial joint or skeleton would occur. Collision angle for: supine position at maximum abduction in flexion was 77±16° in flexion and 82±57° in medial rotation; top position at maximum extension was 36±16° in flexion and 68±53° in medial rotation; top position at maximum flexion was 12±9° in flexion and 14±11° in medial rotation; kneeling position at maximum extension was 115±1° in flexion and 127±44° in medial rotation; and kneeling position at maximum flex-ion was 14±8° in flexion and 17±11° in medial rotation. The present study only assessed risk for dislocation caused by collision with the artificial joint or skeleton, and did not take into account the effects of soft tissue. However, we were able to quantitatively assess angle of the hip joint for some leg positions involved with various common coital positions. The results showed that the supine position at maximum abduction in flexion is relatively safe, since the range of motion before collision would occur was relatively wide. In addition, top and kneeling positions at maximum extension were relatively safe, but caution must be exercised at maximum flexion, as not much extra angle was available in flexion and medial rotation

Purpose

The purpose of this study was to clarify the relationship between the laxity of surrounding soft tissue and artificial joint kinetics during knee articulation, where total knee arthroplasty had been performed using ceramic LFA artificial knee joints (LFA-TKA below) from Japan Medical Materials (JMM).

In orthopaedics new objective functional outcome tools are required to validate the benefits of new surgical techniques or implants for which classic scores such as the KSS, HHS or Womac have been shown not to be discriminative enough. Inertia based motion analysis (IMA) is a cheap, fast and simple technique which requires no gait lab or specialist personnel and thus is suitable for routine clinical outcome assessment. IMA on gait has been validated for total knee replacement (TKR) but normal gait was considered not demanding enough for certain orthopaedic differences. Sit-stand-Sit is a more demanding task of daily activity which can be assessed quickly during consultation. This study investigates whether an IMA assessed sit-stand-sit test can differentiate healthy subjects from pre-op TKR patients. Rising (sit-to-stand) from a chair and sitting down (stand-to-sit) at comfortable, self-selected speed was measured three time using a triaxial accelerometer (range: +/−2g, f=100Hz, 64×62×13mm, m=54g) taped to the sacrum. The chair (no armrests) was height adjustable (legs at 90deg flexion) to level the effort for different body heights. 70 healthy volunteers (f/m=48/22, age range: 17–81yrs) were compared to a pathological group of 20 patients with knee osteoarthritis indicated for unilateral TKR (Biomet Vanguard) measured at 1–10 days pre-op (f/m=11/9; mean age: 65.6yrs, range: 45–79; KSS: 43.5, range: 5–65). The healthy group was split into two subgroups, an age-matched “Old” group (> 50yrs: n1=28, mean age: 65.2yrs) and a “Young” group (< 50yrs: n2=32, mean age: 28.0yrs). Motion parameters derived were the time to stand up (Tup), time to sit down (Tdwn), the time difference between rising and sitting down (Tu−d) and the combined time of rising and sitting down (tu+d) as mean values and per individual repetition. All motion parameters were sign. slower with higher variance for the pre-TKR versus the healthy subjects, even when compared to the age-matched subgroup (except Tu−d). Threshold values could be defined to delineate healthy from pathological performance, e.g. Tup> 220ms (6/70=9% vs 17/20=85%, p< 0.01) or Tdwn> 240ms (4/70=6% vs 18/20=90%, p< 0.01) producing high test sensitivity (90%, C.I. 72–98) and specificity (94%, C.I. 89–97). In some false positives (3/6) originally unknown orthopaedic problems were identified in retrospect. The simple IMA assessed sit-stand-sit test produced motion parameters comparable to values reported for smaller subject groups using methods unsuitable for routine clinical application (e.g. electrogoniometry). Healthy and pathological motion could be distinguished with high sensitivity and specificity even versus age matched controls supporting the validity to use the IMA assessed sit-stand-sit test to complement classic outcome scores with an objective functional component