Aims. This study aimed to analyze kinematics and kinetics of the tibiofemoral joint in healthy subjects with valgus, neutral, and varus limb alignment throughout multiple gait activities using dynamic videofluoroscopy. Methods. Five subjects with valgus, 12 with neutral, and ten with varus limb alignment were assessed during multiple complete cycles of level walking, downhill walking, and stair descent using a combination of dynamic videofluoroscopy, ground reaction force plates, and optical motion capture. Following 2D/3D registration, tibiofemoral kinematics and kinetics were compared between the three limb alignment groups. Results. No significant differences for the rotational or translational patterns between the different limb alignment groups were found for level walking, downhill walking, or stair descent. Neutral and varus aligned subjects showed a mean centre of rotation located on the medial condyle for the loaded stance phase of all three gait activities. Valgus alignment, however, resulted in a centrally located centre of rotation for level and downhill walking, but a more medial centre of rotation during stair descent. Knee adduction/abduction moments were significantly influenced by limb alignment, with an increasing knee adduction moment from valgus through neutral to varus. Conclusion. Limb alignment was not reflected in the condylar kinematics, but did significantly affect the knee adduction moment. Variations in frontal plane limb alignment seem not to be a main modulator of condylar kinematics. The presented data provide insights into the influence of anatomical parameters on tibiofemoral kinematics and kinetics towards enhancing clinical decision-making and surgical restoration of natural knee joint motion and loading. Cite this article: Bone Joint Res 2024;13(9):485–496

Purpose of the study: To our knowledge, only qualitative data is available concerning the tension placed on the first carpometacarpal ligaments as a function of joint motion. The three articles published in the literature have provided discordant data. We conducted a quantitative study. Material and methods:. Digitalized computed tomographies of the carpometacarpal joints magnified threefold were fed to a Stratasys® machine which created a rapid «polystyrene shock» prototype of the first and second metacarpals as well as the trapezium and the trapezoid. After a preliminary study of the behavior observed with various materials, rubber with known consistency was used to simulate the different ligaments. The first metacarpal was submitted to six movements in defined directions starting from the neutral position (in accordance with Pieron, 1973). Ligament lengthening observed for each movement from the resting position of the first metacarpal was used to define the direction producing the greatest lengthening. This lengthening was measured directly with a graduated ruler under 2.5 x optical magnification. Results: The anterior oblique ligament was under tension in the positions close to extension (positions L and D). The posterior oblique ligament was under tension in the position of ulnar finger opposition and in volar abduction (positions K and F). The inter-osseous ligament was under ension in volar abduction, opposition and flexion (positions F, K, J). A complex behavior was observed, best described by two portions, medial and lateral. Discussion: This preliminary study on a model system depended on the interpretation of the ligament and joint surface anatomy. The method of creating joint motion described by Pieron enables comparison between two studies but does not correspond to the physiological position. Conclusion: For a small-sized joint, magnification of the bony pieces and use of optical magnification facilitates apprehension of ligament lengthening during joint motion. This method can be used to better assess maximal range of motion according to ligament deformations observed in relation to joint solicitation

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.

Purpose: Accurate measurement of dynamic joint motion remains a clinical challenge. To address this problem, we have developed a low-dose clinical procedure using the Roentgen Single-plane Photogrammetric Analysis (RSPA) technique. A validation study was performed in a clinical setting, using a conventional digital flat-panel radiography system. Method: To validate the technique, three experiments were performed: assessment of static accuracy, dynamic repeatability and measurement of effective dose. A knee joint phantom, imbedded with tantalum markers, was utilized for the experiments. Relative spatial positions of the markers were reconstructed using Radiostereometric Analysis (RSA). A digital flat-panel radiography system was used for image acquisition, and the three-dimensional pose of each segment was determined from single-plane projections by applying the RSPA technique. All images were processed using software developed in-house. To assess static accuracy, the phantom was mounted onto a three-axis translational stage and moved through a series of displacements ranging from 0 to 500 μm. Images of the phantom were acquired at each position. Accuracy was calculated by analyzing differences between reconstructed and applied displacements. To assess dynamic repeatability, the phantom was mounted on a six-axis robot, programmed to apply a flexion-extension movement to the joint. Multiple cine acquisitions of the moving phantom were acquired (30 fps, 4 ms exposure). Repeatability was calculated by analyzing the variation between motions reconstructed from repeated acquisitions. The effective dose of the procedure was measured using an ion-chamber dosimeter. The ion chamber was positioned between the phantom and x-ray source, facing the source. Entrance exposure was measured for multiple acquisitions, from which the effective dose was calculated. Results: The accuracy determined from the static assessment was 25 μm and 450μm at the 95% confidence intervals for translations parallel and orthogonal to the image plane, respectively. Repeatability of the motion reconstructed from dynamic acquisitions was better than ± 200 μm for translations and ± 0.1 for rotations. The average effective dose for a 6 second dynamic acquisition was approximately 2μSv. Conclusion: The proposed clinical procedure demonstrates both a high degree of accuracy and repeatability, and delivers a low effective dose

The purpose of this study was to determine the motion pattern of the Acromio-Clavicular (AC) joint in a normal shoulder with the use of the new 4 Dimensional CT scan.

From April 2010 till January 2011 fourteen healthy volunteers (4 female, 10 male)(mean age 42±11 years) with no previous history of shoulder complaints participated in this study. The 4D CT machine scans motion, allowing a 3D reconstruction of the shoulder joint and its movements. Patients were positioned supine with their arm elevated 90° in the sagittal plane. During the 7 seconds duration of the scan they adducted their arm at that level and then elevated their arm upwards resisted by the gantry for 4 seconds, in this way simulating the clinical Bell-van Riet test for AC pathology.

In the transverse plane the mean AC joint space measured in the neutral position is 1.8±0.5 mm. While adducting the arm the AC joint narrows 0.0±0.4 mm (with a positive value being narrowing and a negative value widening). On resisted elevation the joint space is narrowed 0.2±0.6 mm. The mean antero-posterior (AP) translation in this same plane is 0.2±2.2 mm on adduction (with a positive value being posterior translation of the clavicle and a negative value anterior translation) and 0.4±2.9 mm on resisted elevation.

The new 4D CT scan demonstrates that the AC joint in a normal shoulder mainly translates in an AP direction, rather than being narrowed or widened, when the arm is adducted (with or without resisted active elevation).

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.

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.

A three-dimensional computer model of a total hip replacement was used to examine the relationship between the position of the components, the range of motion and the prosthetic joint contact area. Horizontal acetabular positions with small amounts of acetabular and femoral anteversion provide the largest contact areas, but result in limited joint movement.

These data will allow surgeons to select implant positions that will provide the largest possible joint contact area for a given joint range of motion although these are conflicting goals. In some component positions a truncated spherical prosthetic head resulted in smaller contact areas than a completely spherical head.

Introduction

The anterior cruciate ligament (ACL) is one of the most common ligament injuries. Several ACL reconstructions exist and are consequently performed. An accurate and comprehensive description of knee motion is essential for an adequate assessment of these surgeries, in terms of restoring knee motion.

The April 2023 Foot & Ankle Roundup. 360. looks at: Outcomes following a two-stage revision total ankle arthroplasty for periprosthetic joint infection; Temporary bridge plate fixation and joint motion after an unstable Lisfranc injury; Outcomes of fusion in type II os naviculare; Total ankle arthroplasty versus arthrodesis for end-stage ankle osteoarthritis; Normal saline for plantar fasciitis: placebo or therapeutic?; Distraction arthroplasty for ankle osteoarthritis: does it work?; Let there be movement: ankle arthroplasty after previous fusion; Morbidity and mortality after diabetic Charcot foot arthropathy

Translational models for OA have used a variety of small (mouse, rat) and large (sheep, pig) animal models to evaluate the efficacy of a specific therapy. Clinical trials based on the results of these animal models have yielded mixed results with respect to the treatment of the disease. Due to greater stringency in EU regulations in the use of animal models for research, ex vivo models of OA (e.g. cartilage explants, bioreactors) are being developed to mimic human joint motion as well as the inflammatory milieu (e.g. IL-1β) that can be used to understand efficacy of therapy in a physiological environment. The development of these models can enable therapies to undergo clinical trials in patients without the necessity for long-term animal studies. This presentation will describe the state of the art in this field and will discuss whether there is potential to speed up translation from bench to bedside in the future

Cam-type femoroacetabular impingement is caused by bone excess on the femoral neck abutting the acetabular rim. This can cause cartilage and labral damage due to increased contact pressure as the cam moves into the acetabulum. However, the damage mechanism and the influence of individual mechanical factors (such as sliding distance) are poorly understood. The aim of this study was to identify the cam sliding distance during impingement for different activities in the hip joint. Motion data for 12 different motion activities from 18 subjects, were applied to a hip shape model (selected as most likely to cause damage, anteriorly positioned with a maximum alpha angle of 80°). The model comprised of a pointwise representation of the acetabular rim and points on the femoral head and neck where the shape deviated from a sphere (software:Matlab). The movement of each femoral point was tracked in 3D while an activity motion was applied, and impingement recorded when overlap between a cam point and the acetabular rim occurred. Sliding distance was recorded during impingement for each relevant femoral point. Angular sliding distances varied for different activities. The highest mean (±SD) sliding distance was for leg-crossing (42.62±17.96mm) and lowest the trailing hip in golf swing (2.17±1.11mm). The high standard deviation in the leg crossing sliding distances, indicates subjects may perform this activity in a different manner. This study quantified sliding distance during cam impingement for different activities. This is an important parameter for determining how much the hip moves during activities that may cause damage and will provide information for future experimental studies

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

Aims. To fully quantify the effect of posterior tibial slope (PTS) angles on joint kinematics and contact mechanics of intact and anterior cruciate ligament-deficient (ACLD) knees during the gait cycle. Methods. In this controlled laboratory study, we developed an original multiscale subject-specific finite element musculoskeletal framework model and integrated it with the tibiofemoral and patellofemoral joints with high-fidelity joint motion representations, to investigate the effects of 2.5° increases in PTS angles on joint dynamics and contact mechanics during the gait cycle. Results. The ACL tensile force in the intact knee was significantly affected with increasing PTS angle. Considerable differences were observed in kinematics and initial posterior femoral translation between the intact and ACLD joints as the PTS angles increased by more than 2.5° (beyond 11.4°). Additionally, a higher contact stress was detected in the peripheral posterior horn areas of the menisci with increasing PTS angle during the gait cycle. The maximum tensile force on the horn of the medial meniscus increased from 73.9 N to 172.4 N in the ACLD joint with increasing PTS angles. Conclusion. Knee joint instability and larger loading on the medial meniscus were found on the ACLD knee even at a 2.5° increase in PTS angle (larger than 11.4°). Our biomechanical findings support recent clinical evidence of a high risk of failure of ACL reconstruction with steeper PTS and the necessity of ACL reconstruction, which would prevent meniscus tear and thus the development or progression of osteoarthritis. Cite this article: Bone Joint Res 2022;11(10):739–750

One assumed function of Total Ankle Replacement (TAR) is that by maintaining ankle joint motion we can protect the other hind foot joints from further degredation. 1. However, there is no work to our knowledge that compares hindfoot outcomes between TAR and arthrodesis. Sokolowski et al. found that 68% of TAR patients had no radiological progression of subtalar arthritis after TAR, and 4% went on to fusion. 2. However, no evaluation of the other hindfoot joints was made and no comparison made to other treatment. We performed a retrospective review of all patients at our centre who had had a TAR or ankle arthrodesis since 2002. Case notes and imaging were reviewed and all instances of hindfoot treatment (injections or surgical procedures) noted. Patients were excluded who had no documentation, were followed up at other hospitals, had prior hindfoot fusion, or were having staged surgeries at the time of index treatment. Chi squared analysis was used to compare the cohorts. 214 arthrodesis cases and 302 TAR were eligible. The average age was 57. Average time to follow up was 13 years (4–21). At the time of abstract submission 107 sets of notes had been reviewed fully. Full analysis will be performed by conference. 14% of TAR patients went on to have further procedures to the hindfoot joints while 35% of arthrodesis patients had further procedures (p=0.014). There was also a significant difference in the number of patients progressing to fusion of a further hindfoot joint between groups (TAR- 4%, arthrodesis- 20%, p=0.01). These data suggest that TAR are protective of symptomatic change of hindfoot joints. Patients with TAR had fewer hindfoot fusions than those with arthrodesis and also fewer procedures of any form, including injections

Disorders of human joints manifest during dynamic movement, yet no objective tools are widely available for clinicians to assess or diagnose abnormal joint motion during functional activity. Machine learning tools have supported advances in many applications for image interpretation and understanding and have the potential to enable clinically and economically practical methods for objective assessment of human joint mechanics. We performed a study using convolutional neural networks to autonomously segment radiographic images of knee replacements and to determine the potential for autonomous measurement of knee kinematics. The autonomously segmented images provided superior kinematic measurements for both femur and tibia implant components. We believe this is an encouraging first step towards realization of a completely autonomous capability to accurately quantify dynamic joint motion using a clinically and economically practical methodology

Analyzing shoulder kinematics is challenging as the shoulder is comprised of a complex group of multiple highly mobile joints. Unlike at the elbow or knee which has a primary flexion/extension axis, both primary shoulder joints (glenohumeral and scapulothoracic) have a large range of motion (ROM) in all three directions. As such, there are six degrees of freedom (DoF) in the shoulder joints (three translations and three rotations), and all these parameters need to be defined to fully describe shoulder motion. Despite the importance of glenohumeral and scapulothoracic coordination, it's the glenohumeral joint that is most studied in the shoulder. Additionally, the limited research on the scapulothoracic primarily focuses on planar motion such as abduction or flexion. However, more complex motions, such as internally rotating to the back, are rarely studied despite the importance for activities of daily living. A technique for analyzing shoulder kinematics which uses 4DCT has been developed and validated and will be used to conduct analysis. The objective of this study is to characterize glenohumeral and scapulothoracic motion during active internal rotation to the back, in a healthy young population, using a novel 4DCT approach. Eight male participants over 18 with a healthy shoulder ROM were recruited. For the dynamic scan, participants performed internal rotation to the back. For this motion, the hand starts on the abdomen and is moved around the torso up the back as far as possible, unconstrained to examine variability in motion pathway. Bone models were made from the dynamic scans and registered to neutral models, from a static scan, to calculate six DoF kinematics. The resultant kinematic pathways measured over the entire motion were used to calculate the ROM for each DoF. Results indicate that anterior tilting is the most important DoF of the scapula, the participants all followed similar paths with low variation. Conversely, it appears that protraction/retraction of the scapula is not as important for internally rotating to the back; not only was the ROM the lowest, but the pathways had the highest variation between participants. Regarding glenohumeral motion, internal rotation was by far the DoF with the highest ROM, but there was also high variation in the pathways. Summation of ROM values revealed an average glenohumeral to scapulothoracic ratio of 1.8:1, closely matching the common 2:1 ratio other studies have measured during abduction. Due to the unconstrained nature of the motion, the complex relationship between the glenohumeral and scapulothoracic joints leads to high variation in kinematic pathways. The shoulder has redundant degrees of freedom, the same end position can result from different joint angles and positions. Therefore, some individuals might rely more on scapular motion while others might utilize primarily humeral motion to achieve a specific movement. More analysis needs to be done to identify if any direct correlations can be drawn between scapulothoracic and glenohumeral DoF. Analyzing the kinematics of the glenohumeral and scapulothoracic joint throughout motion will further improve understanding of shoulder mechanics and future work plans to examine differences with age

Introduction. To determine the advantages and risks of plating after lengthening (PAL) of tibia in children and adolescents. Materials and Methods. 35 consecutive tibial lengthenings were done for limb length discrepancy (LLD) in 26 patients. Gradual lengthening by an external fixator from a tibial (usually diaphyseal) osteotomy was followed by internal fixation with a lateral tibial submuscular plate. The mean age at the time of the lengthening was 10.3 years (4.8 – 16.8 years). The aetiology for LLD was congenital in 21, acquired in 3, and developmental in 2 patients. The mean follow-up was 4.3 years (8 months – 9.9 years). Results. The mean lengthening was 5cm (3–8.6cm) or 19.1% (10.8 – 35.2%) of the initial length of tibia. It took 78.8 days to reach the target length at a lengthening rate of 0.75mm/day. The mean time to plate substitution after cessation of lengthening was 24.7days/109 days after osteotomy. This led to an average external fixation index (EFI) of 23.1days/cm. Optimisation of this technique by judicious estimation of timing of plate substitution would reduce the EFI. Consolidation was recorded at 192 days after osteotomy. Bone healing index (BHI) was 39.8days/cm and was age dependent: <12 year olds = 37.5 days/cm; 12 years = 44.7 days/cm. Using the estimated consolidation time if treatment was solely by external fixator, calculated by tripling the time taken to reach target length after osteotomy, the BHI in this series would have been 52.9 days/cm (p < 0.001). Knee flexion recovery to > 90 degrees was noted at 153.5 days after plating. One greenstick fracture occurred 116 days after plate insertion, 1 tibial shaft fracture occurred 315 days post removal of plate - both following injury and were treated conservatively. Six episodes of sepsis, 5 superficial and 1 deep were treated with antibiotic suppression. The plates were removed from 28 tibiae, 437.4 days after insertion. Conclusions. Plating after lengthening not only reduces the fixator time but appears to achieve consolidation faster than if treatment was by external fixation alone. This facilitates early recovery of joint motion and limb function