Acute syndesmotic ankle injuries continue to impose a diagnostic dilemma and it remains unclear whether weighbearing or external rotation should be exerted rotation during the imaging process. Therefore, we aimed to implement both axial load (weightbearing) and external rotation in the assessment of a clinical cohort of patients with syndesmotic ankle injuries syndesmotic using weightbearing CT imaging. In this retrospective comparative cohort study, patients with an acute syndesmotic ankle injury were analyzed using a WBCT (N= 20; Mean age= 31,64 years; SD= 14,07. Inclusion criteria were an MRI confirmed syndesmotic ankle injury imaged by a bilateral WBCT of the ankle during weightbearing and combined weightbearing-external rotation. Exclusion criteria consisted of fracture associated syndesmotic ankle injuries. Three-dimensional (3D) models were generated from the CT slices. Tibiofibular displacement and Talar Rotation was quantified using automated3D measurements (Anterior TibioFibular Distance (ATFD), Alpha Angle, Posterior TibioFibular Distance (PTFD) and Talar Rotation (TR) Angle) in comparison to a cohort of non-injured ankles.

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

Total hip arthroplasty (THA) is one of the most successful surgery. However, patients' expectations have increased over the last two decades in regards to hip function after joint replacement, the patients assume to return their daily and sport activities without major limitations. This presentation will examine the effect of surgical approaches and implant designs as well as rehabilitation protocol on the clinical and biomechanical outcomes after THA. The new implant designs for THA aim to improve joint function whereas the surgical approaches intend to reduce muscle damage to regain muscle strength. One important determinant measured from gait analysis is the hip abduction moment as the abductors play a key role in stabilizing the pelvis in the frontal plane, particularly in phases of transition, such as the single leg stance in walking or stair climbing. This showed that muscle strength needs to be preserved. To minimize the risk of hip joint instability, a strong focus of implant development has been carried out. To illustrate this important concept within the context of gait analysis, I will present two studies that examine the influence of surgical approach and biomechanical reconstruction; and the second, is a prospective RCT comparing a dual mobility implant to a standard total hip replacement

Introduction. Despite decades of clinical research in artificial joints and underlying failure mechanisms, systematical and reproducible identification of reasons for complications in total knee replacements (TKR) remains difficult. Due to the complex dynamic interaction of implant system and biological situs, malfunction eventually leading to failure is multifactorial and remains not fully understood. The aim of present study was to evaluate different TKR designs and positions with regard to joint kinematics and stability under dynamic conditions by using a robot-based hardware-in-the-loop (HiL) setup. Material & methods. An industrial 6-axis robot with 6-axis force-torque sensor mounted into its end-effector moved and loaded real, commercially available TKR (bicondylar, cruciate-retaining) that were in virtual interaction with a subject-specific computational multibody model representing the anatomical situs of the knee joint while performing passive seated deep knee flexion. The subject-specific musculoskeletal multibody model (MMB) included rigid bones of the lower right extremity. Bone and cartilage geometries were reconstructed from MRT/ CT data sets preserving anatomical landmarks and allowing for the calculation of inertial properties. M. quadriceps femoris was modeled as single passive tensile force elements. Knee ligaments were modelled as elastic spring elements with a nonlinear force-displacement characteristic. Providing the flexion angle, the robot moved and loaded the mounted femoral implant component with respect to the tibial component while being in continuous interaction with the MMB. Several influencing parameters like implant position (internal/external rotation, varus/valgus alignment) and design (fixed vs. mobile bearing, tibia-insert height) as well as ligament insufficiency and joint loading on joint kinematics and stability was systematically analysed. Results. Improper implant positioning caused joint instability, which was demonstrated in higher magnitudes of the relative kinematics. Negative effects by incorrect implant positioning could be partially compensated by a mobile bearing design. However, this was accompanied with an increase in tibiofemoral contact forces. High correlation of tibia-insert height on ligament and contact force was found. After releasing ligament structures, lower tibiofemoral contact forces and joint opening during deep knee flexion were observed. Conclusion. By means of HiL simulation different clinical and technical parameters of TKR were evaluated in a systematical and reproducible fashion under physiological-like boundary conditions with regard to joint kinematics and stability. The proposed HiL test setup combining robot-based testing with MMBs can contribute to deeper understanding of knee joint function and improvement of total knee implant systems. Acknowledgement. The authors would like to thank the Deutsche Forschungsgemeinschaft (grant numbers: WO WO 452/8-1, BA 3347/3-1 and KL 2327/4-1) for supporting the project

Little is known on how sensory nerves and osteoclasts affect degenerative processes in subchondral bone in osteoarthritis (OA). Substance P (SP) effects on bone are ambivalent but physiological levels are critical for proper bone quality whereas α-calcitonin gene-related peptide (αCGRP) has anabolic effects. Here, we aimed to analyse the influence of an altered sensory neuropeptide microenvironment on subchondral bone in murine OA. Transection of the medial meniscotibial ligament (DMM) of the right hind leg induced joint instability leading to development of OA. Subchondral bone of tibiae from wildtype (WT), alendronate-treated WT (ALN, osteoclast inhibition), αCGRP- and SP- (Tachykinin (Tac)1) knockout mice was analysed by micro-computed tomography 4 and 12 weeks after DMM or sham surgery. Bone resorption marker CTX-I was measured in serum. We observed osteophytosis in all DMM groups and ALN sham mice 4 weeks after surgery but also in sham groups 12 weeks after surgery. In subchondral bone, bone volume density (BV/TV) increased from 4 to 12 weeks after surgery in DMM WT and Tac1-/− mice. DMM WT mice additionally had increased trabecular numbers (Tb.N.) and decreased trabecular space (Tb.Sp.) over time. Sham mice also showed time-dependent alterations in subchondral bone. In sham WT and αCGRP-/− mice specific bone surface (BS/BV) decreased and trabecular thickness (Tb.Th.) increased from 4 to 12 weeks after surgery while subchondral BV/TV of αCGRP-/− mice increased. Comparison of subchondral bone parameters at each time point showed elevated BV/TV in ALN DMM compared to WT DMM mice 4 weeks after surgery. In addition, both ALN sham and DMM mice showed a reduced BS/BV compared to WT. 4 weeks after sham surgery Tb.Th. was highest in ALN mice. In DMM WT mice Tb.Sp. was higher compared to ALN and αCGRP-/−. 12 weeks after surgery (late OA stage), BS/BV of ALN sham mice was significantly reduced in relation to ALN DMM, WT and Tac1-/− sham, while Tb.Th. increased compared to WT. DMM significantly decreased Tb.N. and increased Tb.Sp. in Tac1-/− compared to sham 12 weeks after surgery. CTX-I concentrations were significantly higher in ALN compared to Tac1-/− mice 4 weeks after sham surgery. 12 weeks after sham surgery CTX-I concentrations of WT mice were increased compared to αCGRP-/− and Tac1-/− mice. Over time, DMM induced stronger changes in subchondral bone of WT mice compared to knockout strains. WT and αCGRP-/− sham mice also show alterations in bone parameters over time indicating age-related effects on bone structure. SP deficiency enhanced DMM-induced structural bone alterations in late stage OA emphasizing the importance of SP under pathophysiological conditions. Osteoclast inhibition with alendronate proved to be preservative for time-dependent changes of subchondral bone observed in both, DMM and sham mice. Interestingly, ALN treatment did not reduce bone turnover marker CTX-I, and additionally promoted early osteophyte formation in sham mice

The health of a synovial joint is relied on normal function and coordination of a group of tissues such as articular cartilage (AC), ligaments, tendons and muscles. Osteoarthritis (OA), which is the most common joint disease, is clinically characterised by lesion of AC. Despite this, injury of a ligament or tendon or muscle generates a joint instability, which accelerates deterioration of AC and progression of OA. Traditional histology is often used to study the pathology of biological tissues. It requires tissue biopsy, which traumatises the donor tissues. Therefore, it is not an idea method for assessing AC, ligaments and tendons as the tissues have a poor healing capability. There is a worldwide demand of an imaging technique that diagnoses the microstructural changes of chondral and connective tissues without biopsy. Confocal arthroscopy (Optiscan Pty Ltd, Australia) possesses a Ø 6.3 mm probe and offers a 0.7 µm lateral imaging resolution and 7 µm axial resolution. It has been successfully used for examining the internal microstructural disorders in rotator cuff tendons of human cadavers without tissue biopsy (WU et al., 2015). This study investigates the capability of confocal arthroscopy as optical histology for assessing the internal microstructure of AC, ligaments, tendons and muscles in a knee joint. Four sheep keen joints were freshly donated by other research unrelated to this study. After 5 ml clinical grade fluorescein solution at 0.05 g/L was injected into the joint cavity of a knee joint, the joint was passively exercising for about 10 minutes. The joint was then open collaterally and washed thoroughly using PBS for acquiring the microstructure of AC, ligaments, tendons and muscles using the confocal arthroscopy. Results: without biopsy, confocal arthroscopy offers an imaging resolution for onsite distinguishing the subtle microstructural difference of AC in the weight-bearing and non-weight bearing region. It also permitted visualising the hierarchical collagen structure in ligaments and tendons at a fibre level, and characterising the muscle nuclei, motor-neurons, moto-neuron synapse and striates of myofibres. Confocal arthroscopy showed the early promise to act as optical histology for studying the microstructure of chondral and a range of connective tissues, which allows understand better the health status of a knee joint. Since a sheep knee joint is very small for operating a normal procedure of an arthroscopic examination, an open knee joint surgery was performed in this study to allow imaging the microstructure of AC and a range of connective tissues. This is accounted as a limitation in the study. Nevertheless, this study demonstrated the development of confocal arthroscopy may lead to optical histology of the internal microstructure of AC and a group of connective tissues, which offers understanding more comprehensively the healthy status of a knee joint

Summary. When a TFCC tear is diagnosed, practitioners should maintain a high level of suspicion for the presence of a concomitant SL or LT ligament tear. Introduction. Disruption of the scapholunate (SL) or lunotriquetral (LT) ligament leads to dorsal and volar intercalated segment instability, respectively, while triangular fibrocartilage complex (TFCC) tears result in distal radioulnar joint (DRUJ) instability. Viegas et al. (1993) demonstrated that 56% of grossly visualised cadaveric wrists had one or more tears of a ligament or of the TFCC. The purpose of this investigation is to quantify the incidence, distribution, and correlation of SL, LT, and TFCC tears in a large group of cadaver wrists using magnetic resonance imaging (MRI). Additionally, statistical analysis was performed to predict. Methods. Spin density weighted, fat suppressed, and STIR MRI scans of the wrist were obtained in 48 fresh frozen cadaver arms using a 3 Tesla MRI scanner. The scans were scrutinised by one of us (PC) – a board certified musculoskeletal radiologist. The dorsal, volar, and membranous portions of the SL and LT ligaments were examined sequentially for the presence of a tear. Similarly, the central disk and radioulnar attachments of the TFCC were inspected for tears. Results. A ligament or the TFCC was labeled as torn if there was a complete tear, partial tear, or perforation of one or more of its components, but not if sole degenerative changes, thinning, or fraying of the fibers was observed. Four of the 48 images could not be interpreted due to unsatisfactory scans. The most prevalent injury was a TFCC tear, which was present in 28 (64%) of the 44 wrists examined. SL ligament tears were discovered in 20 (45%) of the wrists, and LT tears were present in 14 (32%) of the wrists. Moreover, 45% of the wrists examined had a TFCC tear and either a SL or LT ligament tear. Specifically, 50% of the 28 wrists with a TFCC tear had a concomitant LT tear, and 46% had a concomitant SL tear. Discussion. SL, LT, and TFCC tears were found in a substantial portion of the wrists examined. Moreover, the majority of wrists with a TFCC tear also had a SL or LT ligament tear. Viegas et al. found that 70% of wrists with a TFCC perforation also had a LT ligament tear. In our series, 71% had a TFCC tear, and 50% of those had a concomitant LT tear

Objectives

Adult mice lacking the transcription factor NFAT1 exhibit osteoarthritis (OA). The precise molecular mechanism for NFAT1 deficiency-induced osteoarthritic cartilage degradation remains to be clarified. This study aimed to investigate if NFAT1 protects articular cartilage (AC) against OA by directly regulating the transcription of specific catabolic and anabolic genes in articular chondrocytes.

Objectives

In this study, we compared the pain behaviour and osteoarthritis (OA) progression between anterior cruciate ligament transection (ACLT) and osteochondral injury in surgically-induced OA rat models.

Objectives

Mesenchymal stem cells have the ability to differentiate into various cell types, and thus have emerged as promising alternatives to chondrocytes in cell-based cartilage repair methods. The aim of this experimental study was to investigate the effect of bone marrow derived mesenchymal stem cells combined with platelet rich fibrin on osteochondral defect repair and articular cartilage regeneration in a canine model.

Objectives

The purpose of this study was to compare the results and complications of tibial lengthening over an intramedullary nail with treatment using the traditional Ilizarov method.

Objectives

There are various pin-in-plaster methods for treating fractures of the distal radius. The purpose of this study is to introduce a modified technique of ‘pin in plaster’.

Objective

Excessive mechanical stress on synovial joints causes osteoarthritis (OA) and results in the production of prostaglandin E2 (PGE2), a key molecule in arthritis, by synovial fibroblasts. However, the relationship between arthritis-related molecules and mechanical stress is still unclear. The purpose of this study was to examine the synovial fibroblast response to cyclic mechanical stress using an in vitro osteoarthritis model.

Dislocation remains a major concern after total hip replacement, and is often attributed to malposition of the components. The optimum position for placement of the components remains uncertain. We have attempted to identify a relatively safe zone in which movement of the hip will occur without impingement, even if one component is positioned incorrectly. A three-dimensional computer model was designed to simulate impingement and used to examine 125 combinations of positioning of the components in order to allow maximum movement without impingement. Increase in acetabular and/or femoral anteversion allowed greater internal rotation before impingement occurred, but decreases the amount of external rotation. A decrease in abduction of the acetabular components increased internal rotation while decreasing external rotation. Although some correction for malposition was allowable on the opposite side of the joint, extreme degrees could not be corrected because of bony impingement.

We introduce the concept of combined component position, in which anteversion and abduction of the acetabular component, along with femoral anteversion, are all defined as critical elements for stability.

Our aim was to determine the most repeatable three-dimensional measurement of glenoid orientation and to compare it between shoulders with intact and torn rotator cuffs. Our null hypothesis was that glenoid orientation in the scapulae of shoulders with a full-thickness tear of the rotator cuff was the same as that in shoulders with an intact rotator cuff.

We studied 24 shoulders in cadavers, 12 with an intact rotator cuff and 12 with a full-thickness tear. Two different observers used a three-dimensional digitising system to measure glenoid orientation in the scapular plane (ie glenoid inclination) using six different techniques. Glenoid version was also measured. The overall precision of the measurements revealed an error of less than 0.6°.

Intraobserver reliability (correlation coefficients of 0.990 and 0.984 for each observer) and interobserver reliability (correlation coefficient of 0.985) were highest for measurement of glenoid inclination based on the angle obtained from a line connecting the superior and inferior points of the glenoid and that connecting the most superior point of the glenoid and the most superior point on the body of the scapula. There were no differences in glenoid inclination (p = 0.34) or glenoid version (p = 0.12) in scapulae from shoulders with an intact rotator cuff and those with a full-thickness tear. Abnormal glenoid orientation was not present in shoulders with a torn rotator cuff.