Reliability Measurement error s u m m a r yObjective: To estimate the reliability and measurement error of performance-based tests of physical function recommended by the Osteoarthritis Research Society International (OARSI) in people with hip and/or knee osteoarthritis (OA). Design: Prospective repeated measures between independent raters within a session and within-rater over a week interval. Relative reliability was estimated for 51 people with hip and/or knee OA (mean age 64.5 years, standard deviation (SD) 6.21 years; 47% females; 36 (70%) primary knee OA) on the 30s Chair Stand Test (30sCST), 40m Fast-Paced Walk Test (40mFPWT), 11-Stair Climb Test (11-step SCT), Timed Up and Go (TUG), Six-Minute Walk Test (6MWT), 10m Fast-Paced Walk Test (10mFPWT) and 20s Stair Climb Test (20sSCT) using intra-class correlation coefficients (ICC). Absolute reliability was calculated using standard error of measurement (SEM) and minimal detectable change (MDC). Results: Measurement error was acceptable (SEM < 10%) for all tests. Between-rater reliability was: optimal (ICC > 0.9, lower 1-sided 95% CI > 0.7) for the 40mFPWT, 6MWT and 10mFPWT; sufficient (ICC >0.8, lower 1-sided 95% CI > 0.7) for 30sCST, 20sSCT; unacceptable (lower 1-side 95% CI < 0.7) for 11-step SCT and TUG. Within-rater reliability was optimal for 40mFPWT, and 6MWT; sufficient for 30sCST and 10mFPWT and unacceptable for 11-step SCT, TUG and 20sSCT. Conclusions: The 30sCST, 40mFPWT, 6MWT and 10mFPWT, demonstrated, at minimum, acceptable levels of both between and within-rater reliability and measurement error. All tests demonstrated sufficiently small measurement error indicating they are adequate for measuring change over time in individuals with knee/hip OA.

This study determined anterior cruciate ligament (ACL) force and its contributors during a standardized drop-land-lateral jump task using a validated computational model. Healthy females (n=24) who were recreationally active performed drop-land-lateral jump and straight run tasks. Three-dimensional whole-body kinematics, ground reaction forces, and muscle activation patterns from eight lower limb muscles were collected concurrently during both tasks, but only the jump was analyzed computationally, with the run included for model calibration. External biomechanics, muscle-tendon unit kinematics, and muscle activation patterns were used to model lower limb muscle and ACL forces. Peak ACL force (2.3±0.5 BW) was observed at 13% of the stance phase during the drop-land-lateral jump task. The ACL force was primarily developed through the sagittal plane, and muscle was the dominant source of ACL loading. The gastrocnemii and quadriceps were main ACL antagonists (i.e., loaders), while hamstrings were the main ACL agonists (i.e., supporters).

Anterior cruciate ligament (ACL) injury is a common problem with consequences ranging from chronic joint instability to early development of osteoarthritis. Recent studies suggest that changes in brain activity (i.e., functional neuroplasticity) may be related to ACL injury. The purpose of this article is to summarize the available evidence of functional brain plasticity after an ACL injury. A scoping review was conducted following the guidelines of the Joanna Briggs Institute and the Preferred Reporting Items for Systematic Reviews and Meta-Analyses. The terms “brain,” “activity,” “neuroplasticity,” “ACL,” “injury,” and “reconstruction” were used in an electronic search of articles in PubMed, PEDro, CINAHL, and SPORTDiscus databases. Eligible studies included the following criteria: (a) population with ACL injury, (b) a measure of brain activity, and (c) a comparison to the ACL-injured limb (contralateral leg or healthy controls). The search yielded 184 articles from which 24 were included in this review. The effect size of differences in brain activity ranged from small (0.05, ACL-injured vs. noninjured limbs) to large (4.07, ACL-injured vs. healthy control). Moreover, heterogeneity was observed in the methods used to measure brain activity and in the characteristics of the participants included. In conclusion, the evidence summarized in this scoping review supports the notion of functional neuroplastic changes in people with ACL injury. The techniques used to measure brain activity and the presence of possible confounders, as identified and reported in this review, should be considered in future research to increase the level of evidence for functional neuroplasticity following ACL injury.

BackgroundHigher peak external knee flexion moments (KFM) during running has been observed in healthy people wearing athletic footwear compared to barefoot, which may increase risk of knee pathologies such as patellofemoral pain. Currently, no studies have examined whether stability and neutral style athletic shoes influence the peak KFM differently, or explored the underlying biomechanical mechanisms by which footwear alters peak KFM in young females.MethodsLower limb biomechanics of sixty girls aged between 10 and 25 years old were collected while running in footwear (both stability and neutral) and barefoot. The external peak KFM, sagittal plane kinematics, sagittal plane knee ground reaction force (GRF) lever arm and sagittal plane resultant GRF magnitude were analysed by repeated measures Analysis of Variance. Linear mixed models were fit to identify predictors of a change in peak KFM, and to determine if the effects of these predictors differed between footwear conditions.ResultsThe peak KFM was higher wearing both shoe styles compared to barefoot (p < 0.001), while no between-shoe differences were found (p > 0.05). Both shoes also increased kinematic variables at the hip, knee, and ankle (p < 0.05). When all these variables were entered into the mixed model, only a change in the knee-GRF lever arm was predictive of a change in peak KFM wearing shoes compared to barefoot (p < 0.001).ConclusionThese findings provide evidence that stability and neutral shoes increase peak KFM compared to barefoot, which is associated with a change in the knee-GRF lever arm rather than a change in lower limb kinematics. Future studies may consider manipulating footwear characteristics to reduce the knee-GRF lever arm in an effort to reduce peak KFM and the potential risk of patellofemoral pain.Electronic supplementary materialThe online version of this article (10.1186/s13047-018-0307-9) contains supplementary material, which is available to authorized users.

Girls at the latter stages of puberty exhibit higher peak external knee flexion and adduction moments, but not abduction or internal rotation moments. This may be partly attributed to a lower hip flexion but higher hip abduction moment at the time of peak knee moments. Future research should examine whether these differences in knee kinetics between pubertal stages have implications for knee injuries such as patellofemoral pain syndrome.