Context: Objectively evaluating knee stability in multiple planes in individuals with anterior cruciate ligament injury may provide more comprehensive information than evaluating subjectively or in only a single plane. This could support both research and clinical decision making. However, for the clinical value of such an instrument to be evaluated, reliability and validity of the instrument must first be established. Despite multiple available instruments that measure rotational knee stability, it is not clear which of these instruments has adequate reliability and validity. Objective: We performed a systematic review to identify instruments for measuring rotational knee stability and to synthesize the available literature in which validity and reliability were evaluated. Evidence Acquisition: We searched 4 databases for publications reporting reliability or validity of an instrument designed to assess rotational knee stability. A narrative synthesis was used to present the results. Evidence Synthesis: We identified 42 studies evaluating 25 different instruments designed to measure movement while applying a standardized torque or while a tester performed a manual test (eg, pivot shift). There was high heterogeneity in parameters reported and criterion methods used. Intrarater and interrater reliability intraclass correlation coefficients were consistently adequate (>.75) except for when lower torques (ie, 6 N·m or less) were applied or acceleration or jerk was measured instead of laxity. Four out of 19 (21.1%) studies evaluating validity reported very good correlations (r > .8) with a criterion measure. Conclusions: We found no highquality evidence that provided sufficient evidence of both reliability and validity in any device. To evaluate the clinical benefit of objectively evaluating stability in multiple planes, further work is needed to develop, refine, and evaluate this class of devices.

Osteoarthritis (OA) has a complex, heterogeneous and only partly understood etiology. There is a definite role of joint cartilage pathomechanics in originating and progressing of the disease. Although it is still not identified precisely enough to design or select targeted treatments, the progress of this year's research demonstrates that this goal became much closer. On multiple scales - tissue, joint and whole body - an increasing number of studies were done, with impressive results. (1) Technology based instrument innovations, especially when combined with machine learning models, have broadened the applicability of biomechanics. (2) Combinations with imaging make biomechanics much more precise & personalized. (3) The combination of Musculoskeletal & Finite Element Models yield valid personalized cartilage loads. (4) Mechanical outcomes are becoming increasingly meaningful to inform and evaluate treatments, including predictive power from biomechanical models. Since most recent advancements in the field of biomechanics in OA are at the level of a proof op principle, future research should not only continue on this successful path of innovation, but also aim to develop clinical workflows that would facilitate including precision biomechanics in large scale studies. Eventually this will yield clinical tools for decision making and a rationale for new therapies in OA.

Background: Musculoskeletal modelling is used to assess musculoskeletal loading during gait. Linear scaling methods are used to personalize generic models to each participant's anthropometry. This approach introduces simplifications, especially when used in paediatric and/or pathological populations. This study aimed to compare results from musculoskeletal simulations using various models ranging from linear scaled to highly subject-specific models, i.e., including the participant's musculoskeletal geometry and electromyography data. Methods: Magnetic resonance images (MRI) and gait data of one typically developing child and three children with cerebral palsy were analysed. Musculoskeletal simulations were performed to calculate joint kinematics, joint kinetics, muscle forces and joint contact forces using four modelling frameworks: 1) Generic-scaled model with static optimization, 2) Generic-scaled model with an electromyography-informed approach, 3) MRI-based model with static optimization, and 4) MRI-based model with an electromyography-informed approach. Findings: Root-mean-square-differences in joint kinematics and kinetics between generic-scaled and MRI-based models were below 5° and 0.15 Nm/kg, respectively. Root-mean-square-differences over all muscles was below 0.2 body weight for every participant. Root-mean-square-differences in joint contact forces between the different modelling frameworks were up to 2.2 body weight. Comparing the simulation results from the typically developing child with the results from the children with cerebral palsy showed similar root-mean-square-differences for all modelling frameworks. Interpretation: In our participants, the impact of MRI-based models on joint contact forces was higher than the impact of including electromyography. Clinical reasoning based on overall root-mean-square-differences in musculoskeletal simulation results between healthy and pathological participants are unlikely to be affected by the modelling choice.