Introduction Leg length inequalities (LLIs) are a common finding in every orthopaedic practice. They can be classified into anatomical and functional LLIs. LLIs can e.g. cause gait and balance disabilities, low back pain and functional scoliosis of the spine. In patients with a total hip replacement a higher rate of aseptic loosening of the prosthesis was found when LLIs were present (Gurney 2002). Until today LLIs are treated statically by wooden blocs, which are placed under the shorter extremity, until the pelvis is levelled. However, the correction of LLIs should also be evaluated dynamically to examine the influence of correction onto the spine and pelvis during gait. Therefore, we seek to evaluate in this pilot study the influence of simulated LLIs on spine and pelvis during gait. Methods A total of 30 healthy subjects (17 females & 13 males) with an average age of 24.4 years were measured in this study. First, LLIs (1 to 4 cm) were simulated with the subjects standing on a simulation platform, which height could be controlled, as previously described (Betsch 2012). In addition, a specially designed sandal with different insole heights (1 to 4 cm) was used to simulate LLIs under dynamic condition while subjects were walking on a treadmill. Changes in pelvic position and spinal posture caused by the LLIS were measured using a rasterstereographic system (Formetric 4D motion, Diers International GmbH, Germany). All data were checked for Gaussian distribution by the Chi square test. Student t-tests were used to check for differences between the LLIs. The level of significance was set at p

Hop tests are used to determine return to sports after ACL reconstruction. They mostly measure distance and symmetry but do not assess kinematics and kinetics. Recently, biomechanical evaluations have been incorporated into these functional jump tests for the better assessment of return to sport. We assessed the sagittal plane range of motion (ROM) of the knee, the deviation axis of rotation (DAOR), and the vertical ground reaction force (vGRF) normalized to body weight in nine healthy participants during the single leg (SLH) and crossover hop tests (COHT). Participants' leg lengths were measured. Jumping distances were marked in the test area as being 4/5 of the leg length. Four sensors were placed on the thighs, the legs and the feet. These body parts were handled as a single rigid body. Eight 480 Hz cameras were used to capture the movements of these rigid bodies. vGRF at landing were measured using a force plate (Bertec, Inc, USA). The ROM of the knee joint and the DAOR were obtained from kinematic data. Participants' joint kinematics metrics were similar in within-subjects statistical tests for SLH and COHT. We therefore asked whether the repeated vGRF normalized to body weight will be similar in both legs during these jumps. Joint kinematics metrics however were different in between subjects indicating the existence of a personalized jumping strategy. These hop tests can be recorded at the beginning of the training season for each individual, which can establish a comparative evaluation database for prospective lower extremity injury recovery and return to sport after ACL injury

Abstract. OBJECTIVES. Application of deep learning approaches to marker trajectories and ground reaction forces (mocap data), is often hampered by small datasets. Enlarging dataset size is possible using some simple numerical approaches, although these may not be suited to preserving the physiological relevance of mocap data. We propose augmenting mocap data using a deep learning architecture called “generative adversarial networks” (GANs). We demonstrate appropriate use of GANs can capture variations of walking patterns due to subject- and task-specific conditions (mass, leg length, age, gender and walking speed), which significantly affect walking kinematics and kinetics, resulting in augmented datasets amenable to deep learning analysis approaches. METHODS. A publicly available (. https://www.nature.com/articles/s41597-019-0124-4. ) gait dataset (733 trials, 21 women and 25 men, 37.2 ± 13.0 years, 1.74 ± 0.09 m, 72.0 ± 11.4 kg, walking speeds ranging from 0.18 m/s to 2.04 m/s) was used as the experimental dataset. The GAN comprised three neural networks: an encoder, a decoder, and a discriminator. The encoder compressed experimental data into a fixed-length vector, while the decoder transformed the encoder's output vector and a condition vector (containing information about the subject and trial) into mocap data. The discriminator distinguished between the encoded experimental data from randomly sampled vectors of the same size. By training these networks jointly using the experimental dataset, the generator (decoder) could generate synthetic data respecting specified conditions from randomly sampled vectors. Synthetic mocap data and lower limb joint angles were generated and compared to the experimental data, by identifying the statistically significant differences across the gait cycle for a randomly selected subset of the experimental data from 5 female subjects (73 trials, aged 26–40, weighing 57–74 kg, with leg lengths between 868–931 mm, and walking speeds ranging from 0.81–1.68 m/s). By conducting these comparisons for this subset, we aimed to assess the synthetic data generated using multiple conditions. RESULTS. We visually inspected the synthetic trials to ensure that they appeared realistic. The statistical comparison revealed that, on average, only 2.5% of the gait cycle showed significantly differences in the joint angles of the two data groups. Additionally, the synthetic ground reaction forces deviated from the experimental data distribution for an average of 2.9% of the gait cycle. CONCLUSIONS. We introduced a novel approach for generating synthetic mocap data of human walking based on the conditions that influence walking patterns. The synthetic data closely followed the trends observed in the experimental data, also in the literature, suggesting that our approach can augment mocap datasets considering multiple conditions, an approach unfeasible in previous work. Creation of large, augmented datasets allows the application of other deep learning approaches, with the potential to generate realistic mocap data from limited and non-lab-based data. Our method could also enhance data sharing since synthetic data does not raise ethical concerns. You can generate and download virtual gait data using our GAN approach from . https://thisgaitdoesnotexist.streamlit.app/. . 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

Restoring native hip anatomy and biomechanics is important to create a well-functioning total hip arthroplasty (THA). Hip offset and leg length are regarded as the most important biomechanical characteristics. This study investigated their association with clinical outcomes including patient reported outcome measures (PROMs) and functional tests. This prospective cohort study was conducted in 77 patients undergoing primary THA (age=65±11 years). Hip offset and leg length were measured on anteroposterior radiographs of the hip pre- and postoperatively. Participants completed the Western Ontario & McMaster Universities Osteoarthritis Index (WOMAC) and performed functional tests (i.e. gait, single leg stance, sit-to-stand, block step-up) preoperatively, and 3 and 12 months postoperatively. A wearable motion sensor was used to derive biomechanical parameters. Associations between radiographic and functional outcomes were investigated with the Spearman's rho correlation coefficient. Subgroup comparisons were conducted for patients with more than 15% decreased or increased femoral offset after THA. Differences in postoperative offset and leg length had little impact on clinical outcomes. Femoral offset subgroups demonstrated no significantly different WOMAC function scores. In functional tests, patients with >15% decreased femoral offset after THA demonstrated more sagittal plane motion during block step-up (14.43° versus 10.66°; p=0.04) while patients with >15% increased femoral after THA demonstrated more asymmetry of frontal plane motion during block step-up (34.05% versus 14.18%; p=0.03). To create a well-functioning THA, there seems to be a reasonable safe zone regarding the reconstruction of offset and leg length

Infected non-unions of proximal femoral fractures are difficult to treat. If debridement and revision fixation is unsuccessful, staged revision arthroplasty may be required. Non-viable tissue must be resected, coupled with the introduction of an antibiotic-eluting temporary spacer prior to definitive reconstruction. Definitive tissue microbiological diagnosis and targeted antibiotic therapy are required. In cases of significant proximal femoral bone loss, spacing options are limited. We present a case of a bisphosphonate-induced subtrochanteric fracture that progressed to infected non-union. Despite multiple washouts and two revision fixations, the infection remained active with an unfavourable antibiogram. The patient required staged revision arthroplasty including a proximal femoral resection. To enable better function by maintaining leg length and offset, a custom-made antibiotic-eluting articulating temporary spacer, the Cement-a-TAN, was fabricated. Using a trochanteric entry cephalocondylar nail as a scaffold, bone cement was moulded in order to fashion an anatomical, patient-specific, proximal femoral spacer. Following resolution of the infection, the Cement-a-TAN was removed and a proximal femoral arthroplasty was successfully performed. Cement-a-TAN is an excellent temporary spacing technique in staged proximal femoral replacement for infected non-union of the proximal femur where there has been significant bone loss. It preserves mobility and maintains leg length, offset and periarticular soft-tissue tension

Vacuum orthoses are being applied in the care of patients with foot and lower leg conditions, as ankle fractures or sprains. The lower leg is protected and immobilized, which increases mobility. Due to the design, the orthoses lead to a difference in leg length, i.e. the side with the orthosis becomes longer, which changes the gait kinematics. To prevent or mitigate the unfavourable effects of altered gait kinematics, leg length-evening devices (shoe lifts) are offered that are worn under the shoe on the healthy side. Our aim was to evaluate the effect of such a device on the normality of gait kinematics. Gait analysis was conducted with 63 adult, healthy volunteers having signed an informed consent form that were asked to walk on a treadmill at a speed of 4.5km/h in three different conditions:. barefoot - as reference for establishing the normality score baseline. with a vacuum orthosis (VACOPed, OPED GmbH, Germany) and a sport shoe. with a vacuum orthosis and a shoe lift (EVENup, OPED GmbH, Germany). Data was sampled using the gait analysis system MCU 200 (LaiTronic GmbH, Austria). The positions of the joint markers were exported from the software and evaluated for the joint angles during the gait cycle using custom software (implemented in DIAdem 2017, National Instruments). A normality score using a modification of the Gait Profile Score (GPS) was calculated in every 1%-interval of the gait cycle and evaluated with a Wilcoxon signed rank test. The GPS value was reduced by 0.33° (0.66°) (median and IQR) while wearing the shoe lift. The effect was statistically significant, and very large (W = 1535.00, p < .001; r (rank biserial) = 0.52, 95% CI [0.29, 0.70]). The significant reduction of the GPS value indicates a more normal gait kinematics while using the leg length-evening device on the contralateral shoe. This rather simple and inexpensive device thus might improve patient comfort and balance while using the vacuum orthoses

To investigate differences in the drop vertical jump height in female adolescents with an ACL injury and healthy controls and the contribution of each limb in this task. Forty female adolescents with an ACL injury (ACLi, 15.2 ± 1.4 yrs, 164.6 ± 6.0 cm, 63.1 ± 10.0 kg) and thirty-nine uninjured (CON, 13.2 ± 1.7 yrs, 161.7 ± 8.0 cm, 50.6 ± 11.0 kg) were included in this study. A 10-camera infrared motion analysis system (Vicon, Nexus, Oxford, UK) tracked pelvis, thigh, shank, and foot kinematics at 200Hz, while the participants performed 3 trials of double-legged drop vertical jumps (DVJ) on two force plates (Bertec Corp., Columbus, USA) sampled at 2000Hz.The maximum jump height normalised by dominant leg length was compared between groups using independent samples t-test. The maximum vertical ground reaction force (GRFz) and sagittal ankle, knee and hip velocities before take-off were compared between limbs in both groups, using paired samples t-test. The normalised jump height was 11% lower in the ACLi than in the CON (MD=0.04 cm, p=0.020). In the ACLi, the maximum GRFz (MD=46.17N) and the maximum velocities of ankle plantar flexion (MD=79.83°/s), knee extension (MD=85.80°/s), and hip extension (MD=36.08°/s) were greater in the non-injured limb, compared to the injured limb. No differences between limbs were found in the CON. ACL injured female adolescents jump lower than the healthy controls and have greater contribution of their non-injured limb, compared to their injured limb, in the DVJ task. Clinicians should investigate differences in the contribution between limbs during double-legged drop vertical jump when assessing patients with an ACL injury, as this could help identify asymmetries, and potentially improve treatment, criteria used to clear athletes to sport, and re-injury prevention

To investigate if the countermovement jump height differs between ACL injured and uninjured female adolescents and to explore kinematic differences between limbs. Additionally, the association between isometric knee extension strength and jump height was investigated. Thirty-one ACL injured female adolescents (ACLi, 15.3 ± 1.4yrs, 163.9 ± 6.6cm, 63.0 ± 9.3kg) and thirty-eight uninjured (CON, 13.2±1.7yrs, 161.7 ± 8.1cm, 50.6 ± 11.1kg) participated in this study. All participants performed a countermovement jump task, with 3D kinematics collected using a motion analysis system (Vicon, Nexus, Oxford, UK) at 200Hz, and a maximum isometric knee extension task on an isokinetic dynamometer (Biodex Medical Systems, New York, USA) for three trials. The peak torque was extracted from the isometric trials. Independent samples t-test compared the maximum jump height normalised by the dominant leg length between groups, paired samples t-test compared the maximum hip and knee extension and ankle plantar flexion velocities before take-off between limbs in both groups, and a Pearson's correlation test investigated the association between the isometric knee extension strength and jump height. The ACLi jumped 13% lower compared to the CON (p=0.022). In the ACLi, the maximum hip and knee extension and ankle plantar flexion velocities were greater in the non-injured limb, compared to the injured limb; however, no differences between limbs were found in the CON. The isometric knee extension strength of both limbs was positively correlated with jump height (limb 1: r=0.329; p=0.006, and limb 2: r=0.386; p=0.001; whereas limb 1 corresponds to the ACLi injured limb and CON non-dominant limb, and limb 2 to the ACLi non-injured limb and CON dominant limb). ACL injured female adolescents present lower jump height than controls and greater contribution of their non-injured limb, compared to their injured limb, during a countermovement jump task. Also, current results indicate that jump height is positively related to isometric knee extension strength measure

In the congenital hip dysplasia, patients treated with total hip replacement (THR) often report persistent disability and pain, with unsatisfactory function and quality of life. A major challenge is to restore the center of rotation of the hip and a satisfactory abduction function [1]. The position of the acetabular cup during THR might be crucial, as it affects abduction moment and motor function. Recently, several software systems have been developed for surgical planning of endoprostheses. Previously developed software called HipOp [2], which is routinely used in clinics, allows surgeons to properly position the prosthetic components into the 3D space of CT data. However, this software did not allow to simulate the articular range of motion and the condition of the abductor muscles. Our aim is to present HipOpCT, an advanced version of the software that includes 3D musculoskeletal planning, through the application to hip dysplasia patients to add knowledge in the diagnosis and treatment of such patients who need THR. 40 hip dysplasia patients received pre-operative CT scanning of pelvis and thighs and had their THR surgery planned using HipOpCT. The base planning includes import of CT data, positioning of prosthetic components interactively through multimodal display, as well as geometrical measurements of the implant and the host bone. The advanced planning additionally includes evaluation of femoro-acetabular impingement and calculation of leg lengths, abductor muscle lengths and lever arms through the automatic creation of a musculoskeletal model. The musculoskeletal parameters in all patients were calculated during the surgical planning, and the data were processed to evaluate pre- and post-operative differences in leg length discrepancy, length and lever arm of the abductor muscles, and how these parameters correlated. The surgical planning led to an increase in the operated leg length of 7.6 ± 5.7 mm. The variation in abductors lever arm was −0.9% ± 4.8% and significantly correlated with the variation in the operated leg length (r = −0.49), pre-operative leg length discrepancy (r = 0.32) and variation in abductors length (r = −0.32). The variation in abductors length was 6.6% ± 5.5%, and significantly correlated with the variation in the operated leg length (r = 0.92), post-operative leg length discrepancy (r = 0.37), pre-operative abductors length (r = −0.37) and variation in abductors lever arm (r = −0.32). The increase in the operated leg length was strongly correlated to the increase in abductor muscle length. Conversely, abductor lever arms slightly decreased on average, and were inversely correlated to leg length variation and abductors lengths. This interactive technology for surgical planning represent a powerful tool for orthopaedic surgeons to consider the best muscle reconstruction, and for rehabilitation specialists to achieve the best functional recovery based on biomechanical outcomes. In a parallel study, we are investigating how these advanced planning is reflected onto the function, pain and biomechanical outcome after a rehabilitation protocol is completed

Restoration of anatomy is paramount in total hip arthroplasty (THA) to optimise function and stability. Leg-length discrepancy of ≥10mm is poorly tolerated and can be the subject of litigation. We routinely use a multimodal protocol to optimise soft tissue balancing which involves pre-operative templating, leg-length measurement supine and in the lateral position after positioning, and the use of an intra-operative leg-length measurement device to ensure optimisation of leg-length. We have analysed the results of our protocol in restoring leg-length in primary THA. Radiological leg-length was measured in a consecutive series of 50 patients who had THA for unilateral arthritis by an independent observer pre- and post-operatively using validated methods utilising radiological software. The measurements pre- and post-operative were compared. Patients with bilateral hip arthritis and poor imaging were excluded. Leg-length was successfully restored to within 5.0mm of the target leg-length in 84.0% of patients (mean +0.7mm (95% CI +0.2 to +1.1)). The other 14.0% of patients were restored to within 5.1–8.0mm (mean +2.2mm (95% CI −2.7 to +7.1)) and 2.0% of patients were restored to within 8.1–10.0mm. Leg length was accurately restored across the subset of patients within a narrow range of either side of the mean target leg length. Intra-operative measurement of leg length can be difficult but is vital in ensuring appropriate restoration of leg-length. We recommend a similar multimodal protocol to ensure restoration of leg-length within narrow limits to maximise function and patient satisfaction

Abstract. Objectives. 1. To investigate the effect of revision total knee replacement (TKR) on gait kinematics in patients with a primary TKR and instability.2. To compare gait kinematics between patients with a well-functioning TKR and those with a primary TKR and symptoms of instability. Methods. This single-centre observational study is following patients who have had a revision TKR due to knee instability. Data was collected pre- and post-operatively at 8–12 week follow-up. The data was compared to a control group of 18 well-functioning TKR patients. Kinematic gait data was collected during routine clinics using a treadmill-based infrared 3D system (Vicon, Oxford, UK) and a published lower limb marker-set. Patients performed 15 strides at three different speeds: 0.6mph, self-selected, and a ‘slow walk’ normalised to leg length (Froude number 0.09). PROMs questionnaires were collected. NHS ethical approval was obtained. Results. Data was collected for 18 well-functioning TKR patients and 8 revision TKR patients pre- and post-operatively, but only 5 could walk at the normalised speed. When walking at a normalised speed (Froude 0.09), patients with a TKR with instability had reduced range of knee flexion (52° (sd 14)) compared to those with a well-functioning TKR (59° (sd 11)). Short term follow-up after a revision TKR operation demonstrated a stiffer knee (45° (sd 12)). However, those with revision TKR had a more flexed knee during stance phase. Conclusions. At short-term follow-up, this cohort of revision TKR patients appear to have reduced flexion range, while remaining more flexed during stance. This may represent a less efficient gait pattern, which may also adversely affect the implant[1]. Longer term follow-up may demonstrate whether this normalises with post-operative rehabilitation. 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

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

The Exeter Trauma Stem (ETS) is a monoblock unipolar prosthesis currently in use throughout various orthopaedic departments. It can be a useful procedure for specialty trainees in developing modern cementation techniques in hip arthroplasty. We propose that in order for this procedure to be a valid training tool that, as well as having a standardized surgical approach and operative technique, outcomes should be easily assessed and should be similar if performed by either a trainee or consultant. All ETS procedures carried out at our institution from January 2009 until September 2011 were reviewed retrospectively. Patient demographics and operative details were recorded from patient notes. Radiographic evaluation involved the Barrack cementation grading system, Dorr's criteria, stem alignment and leg length measurement. There was no significant difference in operative time between ETS performed by consultant or by specialty trainee. On postoperative x-ray, cement mantles were Barrack grade A or B in 55.6% (trainees) versus 61.9% (consultants). Stem alignment was neutral in 50% and varus in 50% of cases for trainees, versus 28.6% and 71.4% of cases for consultants. In total, 69.2 % of patients had lengthening of the operated limb with a mean increase of 10.4mm (2–25) for trainees and 9.3mm (2–18) for consultants. Both trainees and consultants can attain a good cement mantle. However, from our results stem alignment is less accurate by trainees with half being placed in varus. Our results highlight the difficulty of obtaining correct leg length positioning with the ETS with trainees and consultants having similar discrepancies. The ETS is a useful procedure for orthopaedic trainees to attain adequate skills in modern cementation techniques with similar post-operative radiographic outcomes to consultants. The tendency for trainees to be less accurate with stem positioning could be improved with supervision or careful pre-operative templating

Modular femoral stems for total hip arthroplasty (THA) were introduced to allow additional options for surgeons in controlling leg lengths, offset, and implant stability. This option is widely used in Region Emilia Romagna, Italy, where the study was conducted, having a modular neck stem nearly 35% of primary THA in 2013. Great majority of modular neck is made of Titanium alloy. The study was designed as a retrospective descriptive case series of 67 hips in patients who underwent revision of a THA. All had a Titanium modular neck. In 44 cases revision was due to breakage of the neck, in the remaining 23 it was due to different reasons unrelated to modular neck such as bone fracture, breakage of a ceramic component, cup loosening. Mean follow up was 3.5 yrs. For all patients excised capsule and surrounding tissue were graded for presence of necrosis, inflammatory exudate, lymphocytes, and wear particles using light microscopy of routine paraffin sections stained with hematoxylin and eosin. The retrieved modular neck-body and head-neck junctions were examined for evidence of fretting and corrosion. For some patient dosage of circulating Titanium was obtained. Approval was obtained from institutional review board. It resulted that a variable amount of wear was observed in the first group of patients, with no evidence of lymphocytic reaction, but with variable notes of necrosis. Broken necks showed different patterns of damage, with different degree of corrosion, beside the fatigue fracture. In the second group wear was less evident or absent and negativity of lymphocyte reaction was substantially confirmed. Circulating Titanium ions were one order of magnitude higher in first group (mean 35 micrograms /litre). It can be concluded that fracture of Titanium modular necks occurs progressively, wear does not induce lymphocytic reaction and circulating ions increase. Level of Evidence. III retrospective, comparative study. Acknowledgments. The research was funded by Ministry of Health, grant ‘Early diagnosis of pending failure…’RF 20091472961

In patients with developmental dysplasia of the hip (DDH) chronic joint dislocation induces remodeling of the soft tissue with contractures, muscle atrophy, especially of the hip abductors muscles, leading to severe motor dysfunction, pain and disability (1). The aim pf the present work is to explore if a correct positioning of the prosthetic implants through 3D skeletal modeling surgical planning technologies and an adequate customized rehabilitation can be beneficial for patients with DDH in improving functional performance. The project included two branches: a methodology branch of software development for the muscular efficiency calculation, which was inserted in the Hip-Op surgical planning system (2), developed at IOR to allow surgical planning for patients with complex hip joint impairment; and a clinical branch which involved the use of the developed software as part of a clinical multicentric randomized trial. 50 patients with DDH were randomized in two groups: a simple surgical planning group and an advanced surgical planning with muscular study group. The latter followed a customized rehabilitation program for the strenghtening of hip abductor muscles. All patients were assessed before surgery (T0) and at 3 (T1) and 6 months (T2) postoperatively using clinical outcome (WOMAC, HHS, ROM, MMT, SF12, 10mt WT) and instrumental measures (Dynamometric MT). Pre- and post-operative musculoskeletal parameters obtained by the software (i.e., leg length discrepancy, hip abductor muscle lengths and lever arms) using Hip-Op during the surgical planning were considered. One Way ANOVA for ROM measurement showed a significant improvement at T2 in patients included in experimental group, as well as WOMAC, HHS and SF12 score. The Dynamometric MT score showed significant differences between at T2 (p<0.009). Spearman's rank correlation coefficients showed a significant correlation between both pre- and post-operative abductors lever arm (mm) and hip abductor muscle strength at T2 (ρ = −0.55 pre-op and ρ = −0.51 post-op, p p<0.012 and p<0.02 respectively) and between the operated pre-postoperative leg length variation (mm) and the hip abductor muscle strength (ρ = −0.55, p p<0.013). Results so far obtained showed an improvement of functional outcomes in patients undergoing hip replacement surgery who followed therapeutic diagnostic pathway sincluding a preoperative planning including the assessment of the abductiors lever arm and a dedicated rehabilitation program for the strenghtening of abductios. Particularly interesting is the inverse relationship between the strength of the hip abductor muscles and the variation of the postoperative abductor lever arm

Anterior cruciate ligament deficiency (ACLD) affects the performance of walking in some patients (non-copers) while copers are able to minimize the effects via proper musculoskeletal compensations. Since many daily activities are more challenging than level walking, e.g., obstacle-crossing, it is not clear whether copers are able to cope with such a challenging task. A successful and safe obstacle-crossing requires not only sufficient foot clearance of the swing limb, but also the stability of the body provided mainly by the stance limb. Failure to meet these demands may lead to falls owing to loss of balance or tripping over obstacles. The purpose of the current study was to identify the motor deficits and/or biomechanical strategies in coper and non-coper ACLD patients when crossing obstacles of different heights for a better function assessment. Ten coper and ten non-coper ACLD patients were recruited in the current study. The non-coper ACLD subjects were those who had not been able to return to their pre-injury level activities, had at least once giving way during the last six months and their Lysholm knee scale was less than 70 [1]. Each subject walked and crossed obstacles of heights of 10%, 20% and 30% of their leg lengths at a self-selected pace. Kinematic and kinetic data were measured with a 7-camera motion analysis system (Vicon, Oxford Metrics, U.K.) and two force plates (AMTI, U.S.A.). The leading and trailing toe clearances were calculated as the vertical distances between the toe markers and the obstacle when the toe was directly above the obstacle. Joint angles of both limbs, and joint moments of the stance limb, were calculated. Peak extensor moments at the knee during stance phase and the corresponding joint angles were extracted for statistical analysis. A 3 by 2, 2-way mixed-model analysis of variance with one between-subject factor (group) and one within-subject factor (obstacle height) was performed (α=0.05). SAS version 9.2 was used for all statistical analysis. Compared with the copers, significantly reduced leading and trailing toe clearances were found in the non-coper group (P<0.05). The non-copers showed significantly decreased peak extensor moments (P<0.05) and flexion angle at the affected knee during the stance phase before leading limb crossing (P<0.05). Distinctive gait patterns were identified in coper and non-coper patients with unilateral anterior cruciate ligament deficiency during obstacle crossing. During the stance phase before the un-affected leading limb crossing, the non-copers showed significantly reduced flexion and peak extensor moments at the affected knee (i.e., quadriceps avoidance), primarily owing to the impaired stability at the affected knee. The significantly reduced leading and trailing toe clearances in the non-coper group indicate that the non-coper ACLD patients are at a higher risk of tripping over the obstacle, and may have difficulty in regaining balance owing to the unstable ACLD knee. Advanced rehabilitation program or reconstruction of the ACL is suggested for the non-coper group

Posterior cruciate ligament deficiency (PCLD) leads to structural and proprioceptive impairments of the knee, affecting the performance of daily activities including obstacle-crossing. Therefore, identifying the biomechanical deficits and/or strategies during this motor task would be helpful for rehabilitative and clinical management of such patients. A safe and successful obstacle-crossing requires stability of the body and sufficient foot clearance of the swing limb. Patients with PCLD may face demands different from normal when negotiating obstacles of different heights. The objective of this study was thus to identify the biomechanical deviations/strategies of the lower limbs in unilateral PCLD during obstacle-crossing using motion analysis techniques. Twelve patients with unilateral PCLD and twelve healthy controls participated in the current study with informed written consent. They were asked to walk and cross obstacles of heights of 10%, 20% and 30% of their leg lengths at self-selected speeds. The PCLD group was asked to cross the obstacles with each of the affected and unaffected limb as the leading limb, denoted as PCLD-A and PCLD-U, respectively. The kinematic and kinetic data were measured with a 7-camera motion analysis system (Vicon, Oxford Metrics, U.K.) and two force plates (AMTI, U.S.A.). The angles of the stance and swing limbs (crossing angles) and the moments of the stance limbs (crossing moments) for each joint in the sagittal plane when the leading limb was above the obstacle were calculated for statistical analysis. A 3 by 2, 2-way mixed-model analysis of variance with one between-subject factor (PCLD-A vs. Control, and PCLD-U vs. Control) and one within-subject factor (obstacle height) was performed (α=0.05). Paired t-test was used to compare the variables between PCLD-A and PCLD-U (α=0.05). SAS version 9.2 was used for all statistical analysis. When the leading toe was above the obstacle, the PCLD group showed significantly greater hip flexion in the swing limb but decreased dorsiflexion in the stance limb, both in PCLD-A and PCLD-U (P<0.05). Greater knee flexion and greater ankle dorsiflexion were found in the leading limb in PCLD-A (P<0.05). Meanwhile, the PCLD group showed significantly decreased ankle plantarflexor but increased knee extensor crossing moments in the stance limb compared with the Control (P<0.05). None of the calculated variables were found to be significantly different between PCLD-A and PCLD-U (P>0.05). When crossing the obstacle, patients with PCLD reduced ankle plantarflexor moments that were mainly produced by the gastrocnemius. This may help reduce the posterior instability of the affected knee. Greater knee extensor crossing moments may also help reduce the posterior instability of the standing knee when the leading toe was above the obstacle. The changed joint kinetics as a result of PCLD were not only seen on the affected side but also on the unaffected side during obstacle-crossing. This symmetrical pattern may be necessary in performing functional activities that may require either the affected side or the unaffected side leading. These results suggest that rehabilitative intervention, including muscular strengthening, on both affected and unaffected sides are necessary in patients with unilateral PCLD

Instability following total hip arthroplasty (THA) is an unfortunately frequent and serious problem that requires thorough evaluation and preoperative planning before surgical intervention. Prevention through optimal index surgery is of great importance, as the management of an unstable THA is challenging even for an experienced joints surgeon. However, even after well-planned surgery, a significant incidence of recurrent instability still exists. Moreover leg-length discrepancy (LLD) after THA can pose a substantial problem for the orthopaedic surgeon. Such discrepancy has been associated with complications including nerve palsy, low back pain, and abnormal gait. Consequently we may use a big femoral head or increase femoral offset (FO) in unstable THA for avoiding LLD. However we do not know the relationship between FO and STT. The objective of this study is to assess hip instability of three different FOs in same patient undergoing THA during an operation. We performed 70 patients who had undergone unilateral THA using CT based navigation system at a single institution for advanced osteoarthoritis from May 2013 to May 2014. We used postero-lateral approach in all patients. After cup and stem implantation, we assessed soft tissue tensioning in THA during operation. Trial necks were categorized into one of three groups: standard femoral offset (sFO), high femoral offset (hFO, +4mm compared to sFO) and extensive high femoral offset (ehFO, +8 mm compared to sFO). We measured distance of lift-off about each of three femoral necks using CT based navigation system and a force gauge with hip flexed at 0 degrees and 30 degrees under a traction of lower extremity. Traction force was 40% of body weight. Forty patients had leg length restored to within +/− 3mm of the contralateral side by post-operative CT analysis. We examined these patients. Traction force was 214±41.1Nm. The distances of lift-off were 8.8±4.5mm (sFO), 7.4±4.1mm (eFO), 5.1±3.9mm (ehFO) with 0 degrees hip flexion and neutral abduction(Abd) / adduction(Add) and neutral internal rotation(IR)/ external rotation(ER). The distance of lift-off were 11.5±5.9mm (sFO),10.5±5.5mm (eFO),9.1±5.9mm (ehFO) with 30 degrees hip flexion and neutral Abd / Add and neutral IR/ER. Significant difference was observed between 0 degrees hip flexion and 30 degrees hip flexion on each FO (p<0.05). On changing the distance of lift-off, hFO to ehFO (2.2±1.6mm)was more stable than sFO to hFO (1.4±1.7mm)with 0degrees hip flexion.(p<0.05). On the other hands, hFO to ehFO (1.4±1.6mm) was more stable than sFO to hFO (1.0±1.3mm) with 30 degrees hip flexion. However, we did not find significant difference (p=0.18). Hip instability was found at 30 degrees hip flexion more than at 0 degrees hip flexion. We found that changing ehFO to sFO can lead to more stability improvement of soft tissue tensioning than sFO to eFO, especially at 0 degrees hip flexion. Whereas In a few cases, the distance of lift-off did not change with increasing femoral offset by 4mm. When you need more stability in THA without LLD, We recommend increasing FO by 8mm

Background. Implant stability and is an important factor for adequate bone remodelling and both are crucial in the long-term clinical survival of total hip arthroplasty (THA). Assessment of early bone remodelling on X-rays during the first 2 years post-operatively is mandatory when stepwise introduction of a new implant is performed. Regardless of fixation type (cemented or cementless), early acetabular component migration is usually the weakest link in THA, eventually leading to loosening. Over the past years, a shift towards uncemented cup designs has occurred. Besides the established hydroxyapatite (HA) coated uncemented cups which provide ongrowth of bone, new uncemented implant designs stimulating ingrowth of bone have increased in popularity. These cups initiate ingrowth of bone into the implant by their open metallic structure with peripheral pores, to obtain a mechanical interlock with the surrounding bone, thereby stabilising the prosthesis in an early stage after implantation. This retrospective study assessed bone remodelling, osseointegration and occurrence of radiolucency around a new ingrowth philosophy acetabular implant. Methods. In a retrospectively, single centre cohort study all patients whom underwent primary THA with a Tritanium acetabular component in 2011 were included. Bone remodelling, osseointegration and occurrence of radiolucency were determined by two reviewers from X-ray images that were made at 6 weeks, 3–6-12 and 24 months post-operatively. Bone contact % was calculated based on the original Charnley and DeLee zones. According to Charnley and DeLee the outer surface of an acetabular cup is divided into 3 zones (1-2-3). For our analysis the original 3 zones were further divided into 2 producing 6 zones 1A to 3B. Each of these 6 zones were then further divided into 4 equal sections. We attributed 25 points per section in which complete bone contact without lucency was observed. If lucency was observed no points were attributed to the section. A fully osteointegrated cup in all 24 sections could therefore attain 600 points. The total of each section and zone was subsequently tallied and recalculated to produce the percentage of bone contact on a 1–100% score. Results. In 2011 131 patients; 54 male and 76 female with average age of 60.83 (SD 12.42) and 60.57 (SD 12.11) year respectively underwent primary THA at our institution and all where included in our study cohort. Majority of this cohort underwent primary THA due to osteoarthrosis and most patients were classified ASO I (18%) or ASA II (65%). At two year clinical follow-up two revision were performed. One constituted a femur and acetabulum revision due to leg length difference and a snapping hip phenomenon. Complications included 3 dislocations (all treated policlinic), 4 deep infections (all treated with Genta PMMA beads with prosthesis in situ and healed) and 1 removal of hematoma. In another patient the femoral component was revised due to a peri-prosthetic fracture. Mean bone contact % values for all Charnley and DeLee zones combined were calculated and improved from 68,18% (SD 22,36) at 6 weeks to 73,61% SD (16,26) at 3 months to 84,21% (SD 19,02) at 6 months to 86,90% (SD 16,0) at 1 year to 92,19% (SD 12,74) at two year follow-up. When analysing the bone contact % per individual zone a remarkable difference was found for zones 2A-B. In contrast to zone 1A-B and 3A-B the initial bone contact % was clearly although not significantly lower until two year follow-up. Conclusions. In this study, the bone apposition around Tritanium actebular component was retrospectively assessed until two year clinical. Our results show excellent bone apposition that continues to improve over time (at least until two year clinical follow-up) suggesting that the open trabecular Ti structure of the Tritanium has a positive effect on cup osseointegration. However, some recent reports have shown the development of reactive lines around cups with porous/trabecular metal surfaces, of which the meaning is still unclear. Our analysis indicated that especially acetabular zone 2A-B according to Charnley&DeLee needs time to establish a direct contact of the implant surface and the surrounding bone tissues. Perhaps this might be explained by reaming technique (underreaming vs line to line reaming) resulting in suboptimal seating of the cup. Therefore, careful follow-up of this new implant technology will remain necessary and continued in this study. We aim to improve cohort size and establish results at longer follow-up times. Furthermore we aim to correlate these results to RSA component migration analysis

Summary Statement. Corin has developed bone conserving prosthesis (MiniHip™) to better replicate the physiological load distribution in the femur. This study assessed whether the MiniHip™ prosthesis can better match the pre-osteoarthritic head centre for patient demographics when compared to contemporary long stem devices. Introduction. Leg length and offset discrepancy resulting from Total Hip Replacement (THR) is a major cause of concern for the orthopaedic community. The inability to substitute the proximal portion of the native femur with a device that suitably mimics the pre-operative offset and head height can lead to loss of abductor power, instability, lower back pain and the need for orthodoses. Contemporary devices are manufactured based on predicate studies to cater for the variations within the patient demographic. Stem variants, modular necks and heads are often provided to meet this requirement. The number of components and instruments that manufacturers are prepared to supply however is limited by cost and an unwillingness to introduce unnecessary complexity. This can restrict the ability to achieve the pre-osteoarthritic head centre for all patient morphologies. Corin has developed MiniHip™ to better replicate the physiological load distribution in the femur. This study assessed whether the MiniHip™ prosthesis can better match the pre-osteoarthritic head centre for patient demographics when compared to contemporary long stem devices. Methods. The Dorr classification is a well accepted clinical method for defining femoral endosteal morphology. This is often used by the surgeon to select the appropriate type and size of stem for the individual patient. It is accepted that a strong correlation exists between Flare Index (FI), characterising the thinning of cortical walls and development of ‘stove-pipe’ morphology, and age, in particular for females. A statistical model of the proximal femur was built from 30 full length femoral scans (Imorphics, UK). Minimum and maximum intramedullary measurements calculated from the statistical model were applied to relationships produced by combining Corins work with that of prior authors. This data was then used to generate 2D CAD models into which implants were inserted to compare the head centres achievable with the MiniHip™ compared to those of a contemporary long stem. Results. Results for the CAD overlay indicated the MiniHip prosthesis is better suited to restoring head centre for a range of morphological variations. In contrast, the long stem prosthesis requires a larger size range and increased inventory in terms of stem variants and modular components to achieve the same array of head centres. The disparity between the Corin FI and that of prior authors can be accounted for by the methods employed; the greyscale-based edge detection (Imorphics) compared to a manual identification method. Discussion/Conclusion. By overlaying the Corin MiniHip™ over the CAD representation of anticipated flare index, it is evident that the MiniHip™ stem is more suitable for the anticipated range of morphologies. The versatility of this design enables the restoration of head height and offset regardless of canal geometry, degree of offset and or CCD angle. This is not the case for contemporary long stem devices which rely on a more diaphyseal region for anchorage and stability and therefore depend on stem variants and modularity to cater for morphology changes