The Effect of Progressive Resistance Exercise on Knee Muscle Strength and Function in Participants with Persistent Hamstring Deficit Following ACL Reconstruction: A Randomized Controlled Trial.

OBJECTIVE: To investigate the effect of progressive resistance exercise compared with low-intensity home-based exercises on knee-muscle strength and joint function in people with anterior cruciate ligament (ACL) reconstruction and persistent hamstring strength deficits at 12-24 months after surgery. DESIGN: Randomized controlled superiority trial with parallel groups, balanced randomization (1:1), and blinded outcome assessment. METHODS: People with ACL reconstruction (hamstring autograft) and persistent hamstring muscle strength asymmetry were recruited 1 to 2 years postsurgery and randomized to either 12 weeks of supervised progressive strength training (SNG), or 12 weeks of home-based, low-intensity exercises (CON). The primary outcome was between-group difference in change in maximal isometric knee flexor muscle strength at 12-week follow-up. RESULTS: Fifty-one participants (45% women, 27 ± 6 years) were randomized to SNG (n = 25) or CON (n = 26), with 88% follow-up rate at 12 weeks. People in the SNG group improved their knee flexor muscle strength (0.18 N·m/kg, 95% confidence interval [CI]: 0.07, 0.29; P = .002) more than the CON group, from baseline to 12 weeks. The SNG group also had superior Knee Injury and Osteoarthritis Outcome Scores for Pain (4.6, 95% CI: 0.4, 8.7; P = .031) and daily living function (4.7, 95% CI: 1.2, 8.2; P = .010) compared to the CON group. CONCLUSION: In people with persistent hamstring muscle strength deficits after ACL reconstruction, 12 weeks of supervised progressive strength training was superior to low-intensity home-based exercises for improving maximal knee flexor muscle strength and some patient-reported outcomes. J Orthop Sports Phys Ther 2023;53(1):40-48. Epub: 17 October 2022. doi:10.2519/jospt.2022.11360.

Gait biofeedback training in people with Parkinson's disease: a pilot study.

BACKGROUND: People with Parkinson's disease (PD) are at a high risk of falls, with ~ 60% experiencing a fall each year. Greater mediolateral head and pelvis motion during gait are known to increase the risk of falling in PD, however the ability to modify these aspects of gait has not been examined. Thus, this study aimed to examine whether mediolateral trunk, head and pelvis motion during walking could be successfully decreased in people with PD using real-time biofeedback. METHODS: Participants were provided with real-time biofeedback regarding their mediolateral trunk lean via a visual projection whilst walking along an 8-m indoor walkway. Using the feedback provided, they were asked to reduce the magnitude of their mediolateral trunk lean. Gait was recorded for four conditions (i) Baseline, (ii) Intervention, (iii) immediately Post-Intervention, and (iv) 1-week Follow-Up. Biomechanical variables associated with falls risk were compared between conditions, including normalised mediolateral motion, gait velocity and stride length. RESULTS: A reduction in mediolateral trunk lean, step length and gait velocity from Baseline to the Intervention and Post-intervention conditions was observed. Contrary to this, increased normalised ML pelvis and trunk motion was observed between the Baseline and Intervention conditions, but returned to Baseline levels in the Post-Intervention condition. CONCLUSIONS: Results from the current study suggest that real-time visual biofeedback may be effective at modifying specific gait characteristics that are associated with falls in PD. Further research is required to better understand the influence of this intervention approach on falls incidence. Trial registration Australian New Zealand Clinical Trials Registry ACTRN12620000994987. Registered 10 June 2020 - Retrospectively registered, https://anzctr.org.au/Trial/Registration/TrialReview.aspx?id=380324.

Acute effect of traditional and adaptive metronomes on gait variability in older individuals with a history of falls.

BACKGROUND: Metronome cueing has been shown to reduce gait variability and thereby potentially reduce falls risk in individuals with Parkinson's disease. It is unclear however, if metronome cueing has a similar effect in healthy older adults with a history of falls. AIM: To investigate whether a traditional and/or an adaptive metronome, based on an individual's gait pattern, were effective in reducing gait variability in older adults with a history of falls. METHODS: Twenty older adults (15 women, 71 ± 4.9 years) with a history of falls were included in this cross-over study. Participants received two types of cueing (adaptive and traditional metronome) 1 week apart. The variability of the participants' stride time, stride length, walking speed and duration of double leg support were recorded during three walking conditions (baseline, during feedback and post-feedback gait). Repeated-measures ANOVA was used to assess the possible effects of the two cueing strategies on gait variables. RESULTS: Compared with the baseline condition, participants had significantly increased stride time variability during feedback (F (2) = 9.83, p < 0.001) and decreased double leg support time variability post-feedback (F (2) 3.69, p = 0.034). Increased stride time variability was observed with the adaptive metronome in comparison to the traditional metronome. CONCLUSION: Metronome cueing strategies may reduce double leg support variability in older adults with a history of falls but seem to increase stride time variability. Further studies are needed to investigate if metronome cueing is more beneficial for individuals with greater baseline gait variability than those included in the current study.

Sex differences in postural orientation errors and association with objective and patient-reported function in patients with ACL injury: an exploratory cross-sectional study.

OBJECTIVES: There is limited research on sex differences in postural orientation (ie, alignment between body segments) in people with knee injury measured with a clinically applicable method. An understanding of the relationship between postural orientation and physical function may help guide decision making in rehabilitation. The aims were to evaluate (1) sex differences in visual assessment of Postural Orientation Errors (POEs) and (2) the association between POEs and objective and patient-reported physical function, in men and women with anterior cruciate ligament reconstruction (ACLR). METHODS: Twenty-four women and 29 men (mean 26.7 (SD 6.5) years) with ACLR were included. Six POEs (lower extremity and trunk) were scored from a video of five tasks with varying difficulty to compute POE scores (total and subscores). Objective physical function was evaluated with the single-leg hop for distance and side hop. Patient-reported physical function was evaluated using patient-reported outcome measures (PROMs). RESULTS: Women had significantly more POEs than men (median difference 5.5-25, p≤0.028). More POEs were associated with shorter hop distance and fewer side hops in women (rs= -0.425 to -0.518, p<0.038), but not in men (rs<0.301, p>0.05). No associations were found between POE scores and PROMs, in either sex (rs< -0.246, p>0.05). CONCLUSIONS: Women with ACLR seem to have more POEs compared with men, indicating worse postural orientation. More POEs were associated with worse hop performance, suggesting that POE scores may be used as criteria for rehabilitation progression. The lack of associations between POE scores and PROMs indicate that these measures complement each other.

Do knee abduction kinematics and kinetics predict future anterior cruciate ligament injury risk? A systematic review and meta-analysis of prospective studies.

BACKGROUND: To systematically review the association between knee abduction kinematics and kinetics during weight-bearing activities at baseline and the risk of future anterior cruciate ligament (ACL) injury. METHODS: Systematic review and meta-analysis according to PRISMA guidelines. A search in the databases MEDLINE (PubMed), CINAHL, EMBASE and Scopus was performed. Inclusion criteria were prospective studies including people of any age, assessing baseline knee abduction kinematics and/or kinetics during any weight-bearing activity for the lower extremity in individuals sustaining a future ACL injury and in those who did not. RESULTS: Nine articles were included in this review. Neither 3D knee abduction angle at initial contact (Mean diff: -1.68, 95%CI: - 4.49 to 1.14, ACL injury n = 66, controls n = 1369), peak 3D knee abduction angle (Mean diff: -2.17, 95%CI: - 7.22 to 2.89, ACL injury n = 25, controls n = 563), 2D peak knee abduction angle (Mean diff: -3.25, 95%CI: - 9.86 to 3.36, ACL injury n = 8, controls n = 302), 2D medial knee displacement (cm; Mean diff:: -0.19, 95%CI: - 0,96 to 0.38, ACL injury n = 72, controls n = 967) or peak knee abduction moment (Mean diff:-10.61, 95%CI: - 26.73 to 5.50, ACL injury n = 54, controls n = 1330) predicted future ACL injury. CONCLUSION: Contrary to clinical opinion, our findings indicate that knee abduction kinematics and kinetics during weight-bearing activities may not be risk factors for future ACL injury. Knee abduction of greater magnitude than that observed in the included studies as well as factors other than knee abduction angle or moment, as possible screening measures for knee injury risk should be evaluated in future studies.

Extended Version of a Test Battery for Visual Assessment of Postural Orientation Errors: Face Validity, Internal Consistency, and Reliability.

OBJECTIVE: Undesirable postural orientation may be a risk factor for a second anterior cruciate ligament (ACL) injury. The purpose of this study was to evaluate face validity, internal consistency, and interrater reliability of an extended version of a previous test battery for visual assessment of postural orientation errors (POEs) in patients during the late phase of rehabilitation following ACL reconstruction (ACLR) (ie, when they have initiated jumping exercises). METHODS: This study used a cross-sectional design. Fifty-three patients (45% women) in the late phase of ACLR rehabilitation performed 5 functional tasks of varying difficulty. POEs of the lower extremity and trunk were visually assessed from video and scored on a scale from 0 (good) to 2 (poor). RESULTS: The side-hop and 2 new POEs (femur medial to shank, femoral valgus) were added to the test battery after expert focus group discussions. Internal consistency was calculated for all tasks (α = .712-.823). Interrater reliability showed fair to substantial agreement for femur medial to shank and femoral valgus during all tasks (K = 0.31-0.815) and almost perfect agreement for side-hop (intraclass correlation coefficient = 0.88). CONCLUSIONS: The good internal consistency and reliability after adding side-hop, femur medial to shank, and femoral valgus suggests that this test battery is a suitable tool to quantify postural orientation throughout ACLR rehabilitation. IMPACT: This test battery for visual assessment of POEs was evaluated in a heterogeneous group of patients in different phases of ACLR battery and can be used in clinical practice to measure POEs in patients with ACLR, including in the late phase of rehabilitation to return to sport. This study encourages research on more demanding tasks and additional POEs to cover the entire rehabilitation period after ACL injury or reconstruction.

Early tibial subchondral bone texture changes after arthroscopic partial meniscectomy in knees without radiographic OA: A prospective cohort study.

Arthroscopic partial meniscectomy (APM) may lead to changes in underlying trabecular bone (TB) structure potentially promoting the development of knee joint osteoarthritis. Our aim was to investigate if there are early changes occurring in tibial subchondral TB texture in the leg undergoing medial APM compared with the unoperated non-injured contra-lateral leg. The bone texture was measured as the medial-to-lateral ratio of fractal dimensions (FD) calculated for regions selected on weight-bearing anteroposterior tibiofemoral x-rays. Twenty-one subjects before and 12 months after APM were included from 374 patients scheduled for unilateral medial APM. The medial-to-lateral ratio was calculated for horizontal, vertical, and roughest FDs respectively. Higher FD means higher bone roughness. Each FD was calculated over a range of scales using a variance orientation transform method. Mean values of medial-to-lateral horizontal FD calculated for APM knees at follow-up were higher than those at baseline. For unoperated knees the values were lower. The difference in the horizontal FD change from baseline to follow-up between APM and contra-lateral legs was 0.028 (95% CI, 0.004-0.052). The bone roughness changes may reflect the increase in peak knee adduction moment (KAM) and KAM impulse during walking reported for the same cohort in a previous study. They may also reflect early signs of osteoarthritis development and thus, we speculate that individuals with increased bone texture roughness ratio after APM might be at higher risk of knee osteoarthritis development.

Changes in total lower limb support moment in middle-aged patients undergoing arthroscopic partial meniscectomy - A longitudinal observational cohort study.

BACKGROUND: Patients with a meniscal tear are frequently treated with arthroscopic partial meniscectomy (APM) which may alter the net extension moment across the entire lower limb - known as the total support moment (TSM). PURPOSE: To investigate changes in TSM during walking in patients undergoing APM. METHODS: Three-dimensional motion analysis of walking was performed in individuals with meniscal tear prior to APM and 12 months after. Peak TSM, positive ankle (ASM), knee (KSM), and hip (HSM) moments at the time of peak TSM were calculated together with corresponding angular impulses. RESULTS: Patients (n = 20) were middle aged (45.9 ±â€¯6.3 years) and the majority male (70%). At baseline a lower KSM (mean [95%CI]; 0.59 Nm/BM ·â€¯HT% [-1.93; 3.11], P = 0.048) and a trend towards lower peak TSM (0.46 Nm/BM ·â€¯HT% [-1.82; 2.78], P = 0.099) were observed for the APM leg compared with the contralateral. Pre- versus post-APM change scores indicated a relative decrease in loading of the contralateral leg for peak TSM (-0.49 Nm/BM ·â€¯HT% [-0.96; -0.01], P = 0.047) and a trend towards a relative increase in loading of the APM leg for peak KSM (-0.41 Nm/BM ·â€¯HT% [-0.92; 0.09], P = 0.105). No differences were observed in angular impulse variables. CONCLUSIONS: Prior to APM a strategy to unload the injured knee was manifested by reduced KSM and a tendency to a reduced peak TSM. A more equal distribution of joint moments between injured and contralateral legs was observed 12 months following APM.

Gait characteristics and falls in Parkinson's disease: A systematic review and meta-analysis.

INTRODUCTION: Given the high rate of falls during walking in people with idiopathic Parkinson's disease (PD), identifying at risk individuals and developing targeted interventions to reduce falls incidence is paramount. Numerous studies have investigated gait-related risk factors for falls in PD, however findings are inconsistent across studies, and thus a synthesis of the current evidence is needed to guide clinical practice and the development of interventions to reduce falls risk. The objective of this study was to systematically review the literature regarding the association between walking biomechanics and falls in people with PD, and where possible, perform meta-analyses. METHODS: The study was performed in accordance with the PRISMA guidelines. Databases were searched until January 2018 to identify articles that reported on the association between walking biomechanics and prospective or retrospective falls in people with PD. RESULTS: Twenty-six articles were included (15 prospective studies, 11 retrospective studies). Articles reported on spatiotemporal and kinematic characteristics, and muscle activation patterns. Meta-analyses revealed slower walking speed, lower cadence, shorter strides and more mediolateral head and pelvis motion in those at higher risk of future falls. Findings from prospective and retrospective articles were largely consistent. CONCLUSION: Our findings identify spatiotemporal and kinematic characteristics of gait that are risk factors for falls in PD. Modification of these characteristics may have the potential to mediate falls risk, and future research to investigate this possibility is merited. The influence of body and ground reaction forces, and muscle activation patterns on falls risk in PD is currently under-researched.

The effect of targeted exercise on knee-muscle function in patients with persistent hamstring deficiency following ACL reconstruction - study protocol for a randomized controlled trial.

BACKGROUND: Anterior cruciate ligament (ACL) reconstruction, using hamstring auto-graft is a common surgical procedure, which often leads to persistent hamstring muscle-strength deficiency and reduced function. The purpose of this randomized controlled trial (RCT) is to investigate the effect of a combined, progressive, strength and neuromuscular exercise intervention on knee muscle strength, functional capacity and hamstring muscle-tendon morphology in ACL-reconstructed patients with persistent hamstring muscle-strength deficiency compared with controls. METHODS/DESIGN: The study is designed as a multicenter, parallel-group RCT with balanced randomization (1:1) and blinded outcome assessments (level of evidence: II) and will be reported in accordance with the CONSORT Statement. Fifty ACL-reconstructed patients (hamstring auto-graft) with persistent limb-to-limb knee-flexor muscle-strength asymmetry at 12-24 months' post surgery, will be recruited through outpatient clinics and advertisements. Patients will be randomized to a 12-week progressive, strength and neuromuscular exercise group (SNG) with supervised training twice weekly or a control intervention (CON) consisting of a home-based, low-intensity exercise program. Outcome measures include between-group change in maximal isometric knee-flexor strength (primary outcome) and knee-extensor muscle strength, hamstring-to-quadriceps strength ratios of the leg that has been operated on and Knee injury and Osteoarthritis Outcome Score (KOOS) (secondary outcomes). In addition, several explorative outcomes will be investigated: The International Knee Documentation Committee Subjective Knee Form (IKDC), the Tegner Activity Score, rate of force development (RFD) for the knee flexors and extensors, tendon regeneration and potential muscle hypertrophy at graft harvest site evaluated by magnetic resonance imaging (MRI), postural control, kinetic/kinematic gait characteristics and knee-related functional capacity. DISCUSSION: This RCT is designed to investigate the effect of combined, progressive-resistance and neuromuscular exercises on knee-flexor/extensor strength, in the late rehabilitation phase following ACL reconstruction. Reduced hamstring strength represents a potential risk factor for secondary ACL rupture and accelerated progression of osteoarthritis. If deemed effective, the intervention paradigm introduced in this study may help to improve current treatment strategies in ACL-reconstructed patients. TRIAL REGISTRATION: ClinicalTrials.gov, ID: NCT02939677 (recruiting). Registered on 20 October 2016.

Measurement Properties of a Test Battery to Assess Postural Orientation During Functional Tasks in Patients Undergoing Anterior Cruciate Ligament Injury Rehabilitation.

Study Design Cross-sectional study. Background Visual rating of postural orientation during functional tasks may be a valuable tool to track rehabilitation progress following anterior cruciate ligament (ACL) injury. A valid test battery assessing postural orientation as a separate construct is lacking. Objectives To evaluate measurement properties of a test battery to assess postural orientation in patients with ACL injury. Methods The content validity of functional tasks was assessed by expert focus group discussions. Fifty-one patients (45% women) with ACL injury performed 9 functional tasks of varying difficulty. Interpretability, internal consistency, interrater reliability, and measurement error were assessed for segment-specific postural orientation errors (POEs), within-task POEs, and total POE score. Postural orientation errors were scored on video on an ordinal scale from 0 (no POEs) to 3 (major POEs). Results Stair ascent, deep squat, and crossover hop for distance were excluded in focus group discussions. Postural orientation errors in some tasks were excluded due to floor effects. The mini-squat and drop jump were excluded due to poor internal consistency (α≤.184). Interrater reliability values for segment-specific POEs and within-task POEs yielded fair to almost perfect agreement (κ = 0.429-0.875) and almost perfect agreement for total POE score (intraclass correlation coefficient = 0.842), without systematic differences between raters. The smallest detectable changes were 0.7 and 5 points for groups and individuals, respectively. Conclusion The final test battery (single-leg mini-squat, stair descent, forward lunge, single-leg hop for distance) of 4 POEs (foot pronation, medial knee-to-foot position, hip joint POEs, and trunk segment POEs) demonstrated good measurement properties in people with ACL injury. J Orthop Sports Phys Ther 2017;47(11):863-873. doi:10.2519/jospt.2017.7270.

Frontal plane kinematics predict three-dimensional hip adduction during running.

OBJECTIVES: To investigate if frontal plane kinematics are predictive of three dimensional (3D) hip adduction and hip internal rotation during running. STUDY DESIGN: Cross-sectional. SETTING: Biomechanics laboratory. PARTICIPANTS: Thirty healthy male runners aged 18-45 years. MAIN OUTCOME MEASURES: Two dimensional (2D) angles in the frontal plane (peak pelvic obliquity, peak hip adduction, peak femoral valgus, peak knee valgus and peak tibial valgus) and 3D hip adduction and hip internal rotation during stance phase of running were obtained. RESULTS: Linear regression modelling revealed that peak 2D pelvic obliquity (a drop towards the contralateral leg) and peak femoral valgus significantly predicted 88% of the variance in peak 3D hip adduction (p < 0.001). Frontal plane kinematics however, were not predictive of peak hip internal rotation in 3D (p > 0.05). CONCLUSIONS: Frontal plane kinematics, specifically contralateral pelvic drop and femoral valgus, predicted the vast majority of the variance in 3D hip adduction during the stance phase of running. This indicates that 2D video may have potential as a clinically feasible proxy for measurement of peak 3D hip adduction - a risk factor for patellofemoral pain.

Measurement properties of visual rating of postural orientation errors of the lower extremity - A systematic review and meta-analysis.

OBJECTIVES: To systematically review measurement properties of visual assessment and rating of Postural Orientation Errors (POEs) in participants with or without lower extremity musculoskeletal disorders. METHODS: A systematic review according to the PRISMA guidelines was conducted. The search was performed in Medline (Pubmed), CINAHL and EMBASE (OVID) databases until August 2016. Studies reporting measurement properties for visual rating of postural orientation during the performance of weight-bearing functional tasks were included. No limits were placed on participant age, sex or whether they had a musculoskeletal disorder affecting the lower extremity. RESULTS: Twenty-eight articles were included, 5 of which included populations with a musculoskeletal disorder. Visual rating of the knee-medial-to-foot position (KMFP) was reliable within and between raters, and meta-analyses showed that this POE was valid against 2D and 3D kinematics in asymptomatic populations. Other segment-specific POEs showed either poor to moderate reliability or there were too few studies to permit synthesis. Intra-rater reliability was at least moderate for POEs within a task whereas inter-rater reliability was at most moderate. CONCLUSIONS: Visual rating of KMFP appears to be valid and reliable in asymptomatic adult populations. Measurement properties remain to be determined for POEs other than KMPF.

Hip Biomechanics Are Altered in Male Runners with Achilles Tendinopathy.

PURPOSE: Achilles tendinopathy (AT) is a prevalent injury in running sports. Understanding the biomechanical factors associated with AT will assist in its management and prevention. The purpose of this study was to compare hip and ankle kinematics and kinetics in runners with and without AT. METHODS: Fourteen male runners with AT and 11 healthy male runners (CTRL) ran over ground while lower-limb joint motion and ground reaction force data were synchronously captured. Hip and ankle joint angles, moments, and impulses in all three planes (sagittal, transverse, and frontal) were extracted for analysis. Independent t-tests were used to compare the differences between the AT and the CTRL groups for the biomechanical variables of interest. After Bonferroni adjustment, an alpha level of 0.0026 was set for all analyses. RESULTS: The AT group exhibited an increased peak hip external rotation moment (P = 0.001), hip external rotation impulse (P < 0.001), and hip adduction impulse (P < 0.001) compared with the CTRL group. No significant differences in ankle biomechanics were observed. CONCLUSION: This study presents preliminary evidence indicating that male runners with AT display altered hip biomechanics with respect to their healthy counterparts. Because of the retrospective design of the study, it is unknown whether these alterations are a predisposing factor for the disorder, a result of the condition, or a combination of both. The results of this study suggest that optimizing hip joint function should be considered in the rehabilitation of runners with AT.

The energetic cost of gait retraining: A pilot study of the acute effect.

OBJECTIVE: To investigate the acute effect of gait retraining aimed at reducing tibial peak positive acceleration (PPA) on energetic cost (VO2). DESIGN: Intervention with a pre/post-test design. SETTING: University biomechanics laboratory. PARTICIPANTS: 12 healthy male runners (23.4 ± 5.3 years, 179.7 ± 4.3 cm, 75.6 ± 9.2 kg). MAIN OUTCOME MEASURES: Tibial PPA and oxygen consumption (VO2) were measured after a five minute baseline run and at the end of a gait retraining session aimed at minimizing tibial PPA. RESULTS: Tibial PPA significantly decreased between baseline and after gait retraining (32.6%, p = 0.007). VO2 significantly increased between the two time periods (9.3%, p = 0.008). There was no correlation between change in tibial PPA and change in VO2 (p = 0.956, r = 0.018). CONCLUSION: Practitioners who aim to reduce injury risk by minimizing tibial PPA in runners need to consider the possible acute effect on performance as a result of changes in VO2. Further investigation is warranted to understand the energetic cost of different kinematic strategies used by individuals.

Gender differences in knee abduction during weight-bearing activities: A systematic review and meta-analysis.

BACKGROUND: Increased knee abduction during weight-bearing activities is suggested to be a contributing factor for the high knee injury risk reported in women. However, studies investigating gender difference in knee abduction are inconclusive. OBJECTIVE: To systematically review gender-differences in knee abduction during weight-bearing activities in individuals with or without knee injury. METHODS: A systematic review and meta-analysis were conducted according to the PRISMA guidelines. A search in the databases Medline, CINAHL and EMBASE was performed until September 2015. Inclusion criteria were studies that reported (1) gender differences, (2) healthy individuals and/or those with anterior cruciate ligament (ACL) deficiency or reconstruction or patellofemoral pain PFP, and (3) knee abduction assessed with either motion analysis or visual observation during weight-bearing activity. RESULTS: Fifty-eight articles met the inclusion criteria. Women with PFP had greater peak knee abduction compared to men (Std diff in mean; -1.34, 95%CI; -1.83 to -0.84). In healthy individuals, women performed weight-bearing tasks with greater knee abduction throughout the movement (initial contact, peak abduction, excursion) (Std diff in mean; -0.68 to -0.79, 95%CI; -1.04 to -0.37). In subgroup analyses by task, differences in knee abduction between genders were present for most tasks, including running, jump landings and cutting movements. There were too few studies in individuals with ACL injury to perform meta-analysis. CONCLUSION: The gender difference in knee abduction during weight-bearing activities should be considered in training programs aimed at preventing or treating knee injury.

Modifiable Factors Associated with Knee Abduction During Weight-Bearing Activities: A Systematic Review and Meta-Analysis.

BACKGROUND: Increased knee abduction angle during activity is suggested to be a risk factor for sustaining an anterior cruciate ligament (ACL) injury or developing patellofemoral pain syndrome (PFPS). Knowledge of the modifiable mechanisms that are associated with increased knee abduction will aid in the appropriate design of preventive and rehabilitative strategies for these injuries. OBJECTIVE: Our objective was to systematically review modifiable mechanisms contributing to increased knee abduction in healthy people and in individuals with an ACL injury or PFPS. METHODS: We performed a systematic review and meta-analysis according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. We searched the databases MEDLINE, CINAHL, and Embase until September 2015. Inclusion criteria were studies in healthy individuals and/or those with ACL injury or PFPS reporting (1) muscle strength, muscle activation, proprioception, and/or range of motion (ROM) and (2) knee abduction angle assessed with either motion analysis or visual observation during weight-bearing activity. RESULTS: In total, 33 articles were included. Reduced trunk strength, reduced gluteus maximus amplitude, decreased ankle ROM, and increased hip external rotation ROM were moderately associated with increased knee abduction angle (r -0.34 or higher, standardized difference in means (SDM) greater than -0.39, p < 0.05, articles n = 3, total sample size n = 101-114) in healthy individuals. Decreased strength of hip abductors, external rotators, and extensors and knee flexors were at most weakly associated with increased knee abduction angle (r ≤ 0.21, p = 0.013-0.426, articles n = 2-9, total sample size n = 80-311). Too few articles included patients with knee injury to be included in any meta-analysis. CONCLUSION: The associations identified in this review indicate that investigation of strengthening of the trunk muscles, and improvement of gluteus maximus activation and ankle ROM to change knee kinematics is merited. Studies on modifiable factors associated with increased knee abduction angle in people with knee injury are needed.

The high frequency component of the vertical ground reaction force is a valid surrogate measure of the impact peak.

Identification of the impact peak (IP) from the vertical ground reaction force (vGRF) is required to calculate indices of impact loading during running. The IP, however, is not always clearly discernible. Previous researchers have estimated the timing of the IP using surrogate methods, the most common of which is a set time point of 13% stance (TPS). Information contained within the high frequency (HiF) component of the vGRF may also have a utility as a surrogate measure, but the validity of either approach is currently unknown. The purpose of this study is to evaluate the criterion validity for a newly proposed HiF method and the previously used TPS method against a criterion measure for a group of rear-foot striking runners. Fifty participants ran at a standardized speed (3.3 m·s(-1)) on an instrumented treadmill. Five consecutive stance phases were analyzed for the participant's dominant limb. Bland-Altman was used to assess agreement between the criterion method and each surrogate method. Good agreement of the HiF and TPS methods with the criterion method indicate that both methods are likely to be valid surrogate approaches to estimate vGRF impact loading indices. For all impact loading indices, smaller bias and limits of agreement (LOA) were observed with the HiF method when compared to the TPS method. Therefore, it is concluded that the HiF method should be used in preference to the TPS method when it is available.

Retraining running gait to reduce tibial loads with clinician or accelerometry guided feedback.

OBJECTIVES: Reducing tibial acceleration through gait retraining is thought to reduce the risk of stress fracture development, however current approaches require the use of advanced accelerometry equipment not readily available in the clinical setting. The aim was to compare the effect of clinician guided feedback with accelerometry guided feedback on peak tibial accelerations during running. DESIGN: Repeated measures randomised design. METHODS: Twenty-two healthy male runners were randomised to receive either tibial accelerometry or clinician guided feedback. Peak tibial accelerations were obtained for all participants (i) prior to intervention, (ii) after 10min of feedback, (iii) after a further 10min without feedback, and (iv) 1 week later. RESULTS: Across groups, significant reductions in peak tibial acceleration were observed from baseline to each of the subsequent time points in the order of 19-29% (p=0.001). No between-group differences in peak tibial acceleration were observed at any of the follow-up time points (p=0.434). CONCLUSIONS: These data indicate that in the short term the low cost, low technology, clinician guided approach to retraining running gait may be equally as effective as the more expensive accelerometry guided solution in reducing peak tibial accelerations. Longer term follow-up is required to evaluate the efficacy of both approaches in reducing the risk of stress fracture development.

Forward lunge knee biomechanics before and after partial meniscectomy.

BACKGROUND: Patients following meniscectomy are at increased risk of developing knee osteoarthritis in the tibiofemoral compartment and at the patellofemoral joint. As osteoarthritis is widely considered a mechanical disease, it is important to understand the potential effect of arthroscopic partial meniscectomy (APM) on knee joint mechanics. The purpose of this study was to evaluate changes in knee joint biomechanics during a forward lunge in patients with a suspected degenerative meniscal tear from before to three months after APM. METHODS: Twenty-two patients (35-55 years old) with a suspected degenerative medial meniscal tear participated in this study. Three dimensional knee biomechanics were assessed on the injured and contralateral leg before and three months after APM. The visual analogue scale was used to assess knee pain and the Knee Injury Osteoarthritis Outcome Score was used to assess sport/recreation function and knee-related confidence before and after APM. RESULTS: The external peak knee flexion moment reduced in the APM leg compared to the contralateral leg (mean difference (95% CI)) -1.08 (-1.80 to -0.35) (Nm/(BW × HT)%), p = 0.004. Peak knee flexion angle also reduced in the APM leg compared to the contralateral leg -3.94 (-6.27 to -1.60) degrees, p = 0.001. There was no change in knee pain between the APM leg and contralateral leg (p=0.118). Self-reported sport/recreation function improved (p = 0.004). CONCLUSIONS: Although patients self-reported less difficulty during strenuous tasks following APM, patients used less knee flexion, a strategy that may limit excessive patellar loads during forward lunge in the recently operated leg.