People Are More Variable Than Their Hop Test Would Suggest: Hop Performance and Self-Reported Outcomes Over 11 Years Following ACL Reconstruction.

We aimed to report the trajectory of self-reported outcomes up to 11 years post-ACLR. We also explored the relationship between hop performance at 1 year and: (i) future self-reported knee outcomes; and (ii) risk of subsequent knee events. 124 participants (43 women, mean age 31 ± 8 years) were recruited at 1 year following hamstring-autograft ACLR. Hop performance was assessed with single-forward and side-hop tests. Follow-up was completed at 3 (n = 114), 5 (n = 89) and 11 years (n = 72) post-ACLR. Self-reported outcomes were assessed at each follow-up with the Knee injury Osteoarthritis Outcome Score (KOOS) pain and quality of life (QOL) subscales. Generalized linear mixed models estimated the relationship between hop performance and self-reported outcomes. Subsequent knee events (new injury/surgery) to either knee were recorded, with the relationship between hop performance and risk of subsequent knee events analyzed with Cox proportional hazards. Self-reported knee outcomes were stable (mean change < 10 points) across all timepoints but with major within-sample variability. There was a modest relationship between greater hop performance at 1 year and better future KOOS-pain (average marginal effect [AME] % improvement with + 1 cm single forward hop = 0.06% [95% CI 0.02-0.10]). A nonlinear spline relationship showed better single-forward hop performance was associated with better KOOS-QOL for scores < 108 cm, not present for higher hop scores > 108 cm. There were 21 index and 11 contralateral subsequent knee events. Hop performance was not related to risk of a subsequent knee event (hazard ratio index knee 0.99 [95% CI 0.98-1.02]). In conclusion, self-reported knee pain and quality of life were generally stable across the 11-year follow-up period. Greater hop performance at 1-year post-ACLR was related to better self-reported knee outcomes up to 11-year follow-up (of questionable clinical importance), but not associated with the risk of subsequent knee injury/surgery.

Effectiveness of an anti-inflammatory diet versus low-fat diet for knee osteoarthritis: the FEAST randomised controlled trial protocol.

INTRODUCTION: Chronic inflammation plays a key role in knee osteoarthritis pathophysiology and increases risk of comorbidities, yet most interventions do not typically target inflammation. Our study will investigate if an anti-inflammatory dietary programme is superior to a standard care low-fat dietary programme for improving knee pain, function and quality-of-life in people with knee osteoarthritis. METHODS AND ANALYSIS: The eFEct of an Anti-inflammatory diet for knee oSTeoarthritis study is a parallel-group, assessor-blinded, superiority randomised controlled trial. Following baseline assessment, 144 participants aged 45-85 years with symptomatic knee osteoarthritis will be randomly allocated to one of two treatment groups (1:1 ratio). Participants randomised to the anti-inflammatory dietary programme will receive six dietary consultations over 12 weeks (two in-person and four phone/videoconference) and additional educational and behaviour change resources. The consultations and resources emphasise nutrient-dense minimally processed anti-inflammatory foods and discourage proinflammatory processed foods. Participants randomised to the standard care low-fat dietary programme will receive three dietary consultations over 12 weeks (two in-person and one phone/videoconference) consisting of healthy eating advice and education based on the Australian Dietary Guidelines, reflecting usual care in Australia. Adherence will be assessed with 3-day food diaries. Outcomes are assessed at 12 weeks and 6 months. The primary outcome will be change from baseline to 12 weeks in the mean score on four Knee injury and Osteoarthritis Outcome Score (KOOS4) subscales: knee pain, symptoms, function in daily activities and knee-related quality of life. Secondary outcomes include change in individual KOOS subscale scores, patient-perceived improvement, health-related quality of life, body mass and composition using dual-energy X-ray absorptiometry, inflammatory (high-sensitivity C reactive protein, interleukins, tumour necrosis factor-α) and metabolic blood biomarkers (glucose, glycated haemoglobin (HbA1c), insulin, liver function, lipids), lower-limb function and physical activity. ETHICS AND DISSEMINATION: The study has received ethics approval from La Trobe University Human Ethics Committee. Results will be presented in peer-reviewed journals and at international conferences. TRIAL REGISTRATION NUMBER: ACTRN12622000440729.

Is quadriceps strength associated with patellofemoral joint loading after anterior cruciate ligament reconstruction?

OBJECTIVE: To test whether quadriceps strength is associated with measures of patellofemoral (PF) joint loading during running and hopping in people after an anterior cruciate ligament reconstruction (ACLR). DESIGN: Cross-sectional study. SETTING: Biomechanics laboratory. PARTICIPANTS: Sixty-five participants (24 women; 41 men) 1-2 years post-ACLR. MAIN OUTCOME MEASURES: Peak isometric quadriceps strength for the surgical limb was measured using a dynamometer. Motion analysis and ground reaction force data were combined with musculoskeletal modelling to measure PF joint loading variables for the reconstructed knee (peak knee flexion angle; peak/impulse of the PF joint contact force; time to peak PF joint contact force) during the stance phase of running and during the landing phase of a standardised forward hop. Linear regression analysis (adjusting for age and sex) assessed the association between quadriceps strength and PF joint loading variables. RESULTS: Two significant, albeit modest, associations were revealed. Quadriceps strength was associated with the time to peak PF joint contact force during running (ß = -0.001; 95%CI -0.002 to -0.000; R2 = 0.179) and the impulse of the PF joint contact force during hopping (ß = 0.014; 95%CI 0.003 to 0.024; R2 = 0.159). CONCLUSIONS: A strong link between quadriceps strength and PF joint loading was not evident in people 1-2 years post-ACLR.

Hip rotation muscle strength is implicated in the progression of early post-traumatic osteoarthritis: A longitudinal evaluation up to 5 years following ACL reconstruction.

INTRODUCTION: Following ACL reconstruction (ACLR), deficits in hip muscle strength and relationships to future outcomes are unknown. METHODS: 111 participants one year after ACLR, completed hip external rotation (ER) and internal rotation (IR) strength assessment. At 1 (n = 111) and 5 (n = 74) years post-ACLR, participants completed a battery of functional, symptomatic (Knee Osteoarthritis Outcome Score (KOOS)) and structural assessments (radiography, magnetic resonance imaging (MRI)). Cartilage health of the patellofemoral and tibiofemoral compartments was assessed with the semiquantitative MRI Osteoarthritis Knee Score. Hip rotation strength was compared between-limbs, and relationships between hip strength at 1 year and functional, symptomatic and cartilage outcomes at 1 and 5 years were investigated with regression models. RESULTS: The index (ACLR) limb had weaker hip ER (but not IR) strength compared to the contralateral side (standardised mean difference ER = -0.33 (95%CI -0.60, -0.07; IR = -0.11 (95%CI -0.37, 0.15). Greater hip ER and IR strength was associated with superior function at 1 and 5 years, and better KOOS-Patellofemoral symptoms at 5 years. Greater hip ER strength was associated with lower odds of worsening tibiofemoral cartilage lesions at 5 years (odds ratio 0.01, 95%CI 0.00, 0.41). CONCLUSION: Hip rotation strength may play a role in worsening function, symptoms and cartilage health after ACLR.

Patellofemoral joint loading and early osteoarthritis after ACL reconstruction.

Patellofemoral joint (PFJ) osteoarthritis is common following anterior cruciate ligament reconstruction (ACLR) and may be linked with altered joint loading. However, little is known about the cross-sectional and longitudinal relationship between PFJ loading and osteoarthritis post-ACLR. This study tested if altered PFJ loading is associated with prevalent and worsening early PFJ osteoarthritis post-ACLR. Forty-six participants (mean ± 1 SD age 26 ± 5 years) approximately 1-year post-ACLR underwent magnetic resonance imaging (MRI) and biomechanical assessment of their reconstructed knee. Trunk and lower-limb kinematics plus ground reaction forces were recorded during the landing phase of a standardized forward hop. These data were input into a musculoskeletal model to calculate the PFJ contact force. Follow-up MRI was completed on 32 participants at 5-years post-ACLR. Generalized linear models (Poisson regression) assessed the relationship between PFJ loading and prevalent early PFJ osteoarthritis (i.e., presence of a PFJ cartilage lesion at 1-year post-ACLR) and worsening PFJ osteoarthritis (i.e., incident/progressive PFJ cartilage lesion between 1- and 5-years post-ACLR). A lower peak PFJ contact force was associated with prevalent early PFJ osteoarthritis at 1-year post-ACLR (n = 14 [30.4%]; prevalence ratio: 1.37; 95% confidence interval [CI]: 1.02-1.85) and a higher risk of worsening PFJ osteoarthritis between 1- and 5-years post-ACLR (n = 9 [28.1%]; risk ratio: 1.55, 95% CI: 1.13-2.11). Young adults post-ACLR who exhibited lower PFJ loading during hopping were more likely to have early PFJ osteoarthritis at 1-year and worsening PFJ osteoarthritis between 1- and 5-years. Clinical interventions aimed at mitigating osteoarthritis progression may be beneficial for those with signs of lower PFJ loading post-ACLR.

Patellofemoral and tibiofemoral joint loading during a single-leg forward hop following ACL reconstruction.

Altered biomechanics are frequently observed following anterior cruciate ligament reconstruction (ACLR). Yet, little is known about knee-joint loading, particularly in the patellofemoral-joint, despite patellofemoral-joint osteoarthritis commonly occurring post-ACLR. This study compared knee-joint reaction forces and impulses during the landing phase of a single-leg forward hop in the reconstructed knee of people 12-24 months post-ACLR and uninjured controls. Experimental marker data and ground forces for 66 participants with ACLR (28 ± 6 years, 78 ± 15 kg) and 33 uninjured controls (26 ± 5 years, 70 ± 12 kg) were input into scaled-generic musculoskeletal models to calculate joint angles, joint moments, muscle forces, and the knee-joint reaction forces and impulses. The ACLR group exhibited a lower peak knee flexion angle (mean difference: -6°; 95% confidence interval: [-10°, -2°]), internal knee extension moment (-3.63 [-5.29, -1.97] percentage of body weight × participant height (body weight [BW] × HT), external knee adduction moment (-1.36 [-2.16, -0.56]% BW × HT) and quadriceps force (-2.02 [-2.95, -1.09] BW). The ACLR group also exhibited a lower peak patellofemoral-joint compressive force (-2.24 [-3.31, -1.18] BW), net tibiofemoral-joint compressive force (-0.74 [-1.20, 0.28] BW), and medial compartment force (-0.76 [-1.08, -0.44] BW). Finally, only the impulse of the patellofemoral-joint compressive force was lower in the ACLR group (-0.13 [-0.23, -0.03] body weight-seconds). Lower compressive forces are evident in the patellofemoral- and tibiofemoral-joints of ACLR knees compared to uninjured controls during a single-leg forward hop-landing task. Our findings may have implications for understanding the contributing factors for incidence and progression of knee osteoarthritis after ACLR surgery.

Poor functional performance 1 year after ACL reconstruction increases the risk of early osteoarthritis progression.

BACKGROUND: Not meeting functional performance criteria increases reinjury risk after ACL reconstruction (ACLR), but the implications for osteoarthritis are not well known. OBJECTIVE: To determine if poor functional performance post-ACLR is associated with risk of worsening early osteoarthritis features, knee symptoms, function and quality of life (QoL). METHODS: Seventy-eight participants (48 men) aged 28±15 years completed a functional performance test battery (three hop tests, one-leg-rise) 1 year post-ACLR. Poor functional performance was defined as <90% limb symmetry index (LSI) on each test. At 1 and 5 years, MRI, Knee injury Osteoarthritis Outcome Score (KOOS) and International Knee Documentation Committee (IKDC) subjective form were completed. Primary outcomes were: (i) worsening patellofemoral and tibiofemoral MRI-osteoarthritis features (cartilage, bone marrow lesions (BMLs) and meniscus) and (ii) change in KOOS and IKDC scores, between 1 and 5 years. RESULTS: Only 14 (18%) passed (≥90% LSI on all tests) the functional test battery. Poor functional performance on the battery (all four tests <90% LSI) 1 year post-ACLR was associated with 3.66 times (95% CI 1.12 to 12.01) greater risk of worsening patellofemoral BMLs. A triple-crossover hop <90% LSI was associated with 2.09 (95% CI 1.15 to 3.81) times greater risk of worsening patellofemoral cartilage. There was generally no association between functional performance and tibiofemoral MRI-osteoarthritis features, or KOOS/IKDC scores. CONCLUSION: Only one in five participants met common functional performance criteria (≥90% LSI all four tests) 1 year post-ACLR. Poor function on all four tests was associated with a 3.66 times increased risk of worsening patellofemoral BMLs, and generally not associated with decline in self-reported outcomes.

Does patellar alignment or trochlear morphology predict worsening of patellofemoral disease within the first 5 years after anterior cruciate ligament reconstruction?

PURPOSE: We described patellofemoral alignment and trochlear morphology at one and five years after anterior cruciate ligament reconstruction (ACLR), and evaluated the associations between alignment and trochlear morphology (at one year) and worsening patellofemoral osteoarthritis (OA) features by five years. We also evaluated the associations between alignment and morphology to self-reported pain and function (Knee injury and Osteoarthritis Outcome Score, KOOS) at five years. MATERIALS AND METHODS: In this longitudinal observational study, we followed 73 participants (mean age 29[9] years, 40% women) from one- to five-years after ACLR. Using MRI, we measured alignment and morphology, and scored cartilage and bone marrow lesions at both time points. We used mixed effects and linear regression models to achieve our stated aims. RESULTS: Greater lateral patella displacement increased risk of cartilage worsening (Odds Ratio [95% CI]: 1.09 [1.01, 1.16]); while less lateral tilt (0.91 [0.83, 0.99]) and greater trochlear angle (0.88 [0.77, 1.00]) were protective. Greater medial trochlear inclination increased risk of bone marrow lesion worsening (1.12 [1.04, 1.19]); while greater trochlear angle was protective (0.80 [0.67, 0.96]). Greater lateral displacement was associated with worse self-reported KOOS sport and recreation scores (ß [95% CI]: -11.0 [-20.9, -1.2]) and quality of life scores (-10.5 [-20.4, -0.7]). CONCLUSIONS: Lateral displacement, lateral tilt, and morphology at 1 year post-ACLR altered the risk of worsening patellofemoral OA features four years later. Lateral displacement was the only measure associated with worse self-reported symptoms at five years. These findings may lead to novel treatment strategies for secondary prevention after ACLR.

Greater knee flexion excursion/moment in hopping is associated with better knee function following anterior cruciate ligament reconstruction.

PURPOSE: Individuals with impaired knee function after anterior cruciate ligament reconstruction (ACLR) may be at greater risk of developing knee osteoarthritis related to abnormal knee joint movement and loading. The aim of this study was to assess the association between knee biomechanics and knee laxity during hopping and clinically assessed knee function (i.e., patient-reported knee function and hop tests) following ACLR. METHODS: Sixty-six participants (23 women, mean age 28 ± 6 years, mean 18 ± 3 months following ACLR) completed a standardized single-leg hopping task. Three-dimensional movement analysis was used to assess knee flexion excursion and body weight/height normalized knee flexion moments during landing for the involved limb. Anterior-posterior knee laxity was assessed with a KT-1000 knee arthrometer. Participants then completed a patient-reported knee function questionnaire and three separate hop tests (% of uninvolved limb) and were divided into poor and satisfactory knee function groups (satisfactory: ≥85% patient-reported knee function and ≥ 85% hop test symmetry). Associations between knee function and hop biomechanics/knee laxity were assessed using logistic regression and interquartile range scaled odds ratios (ORIQR). RESULTS: Greater knee flexion excursion (ORIQR 2.9, 95%CI 1.1-7.8), greater knee flexion moment (ORIQR 4.9, 95%CI 1.6-14.3) and lesser knee laxity (ORIQR 4.7, 95%CI 1.5-14.9) were significantly associated with greater odds of having satisfactory knee function (≥ 85% patient-reported knee function and ≥ 85% hop test symmetry). CONCLUSION: Greater knee flexion excursion/moment during hop-landing and lesser knee laxity is associated with better patient-reported knee function and single-leg hop test performance following ACLR. Patients with lower levels of knee function following ACLR demonstrated hop-landing biomechanics previously associated with early patellofemoral osteoarthritis. Therefore, interventions aimed at improving hop landing biomechanics in people with poor knee function are likely required. LEVEL OF EVIDENCE: III, Cross-sectional study.

Worsening Knee Osteoarthritis Features on Magnetic Resonance Imaging 1 to 5 Years After Anterior Cruciate Ligament Reconstruction.

BACKGROUND: An anterior cruciate ligament (ACL) injury is a well-established risk factor for the long-term development of radiographic osteoarthritis (OA). However, little is known about the early degenerative changes (ie, <5 years after injury) of individual joint features (ie, cartilage, bone marrow), which may be reversible and responsive to interventions. PURPOSE: To describe early degenerative changes between 1 and 5 years after ACL reconstruction (ACLR) on magnetic resonance imaging (MRI) and explore participant characteristics associated with these changes. STUDY DESIGN: Case-control study; Level of evidence, 3. METHODS: Seventy-eight participants (48 men; median age, 32 years; median body mass index [BMI], 26 kg/m2) underwent 3.0-T MRI at 1 and 5 years after primary hamstring autograft ACLR. Early tibiofemoral and patellofemoral OA features were assessed with the MRI Osteoarthritis Knee Score. The primary outcome was worsening (ie, incident or progressive) cartilage defects, bone marrow lesions (BMLs), osteophytes, and meniscal lesions. Logistic regression with generalized estimating equations evaluated participant characteristics associated with worsening features. RESULTS: Worsening of cartilage defects in any compartment occurred in 40 (51%) participants. Specifically, worsening in the patellofemoral and medial and lateral tibiofemoral compartments was present in 34 (44%), 8 (10%), and 10 (13%) participants, respectively. Worsening patellofemoral and medial and lateral tibiofemoral BMLs (14 [18%], 5 [6%], and 10 [13%], respectively) and osteophytes (7 [9%], 8 [10%], and 6 [8%], respectively) were less prevalent, while 17 (22%) displayed deteriorating meniscal lesions. Worsening of at least 1 MRI-detected OA feature, in either the patellofemoral or tibiofemoral compartment, occurred in 53 (68%) participants. Radiographic OA in any compartment was evident in 5 (6%) and 16 (21%) participants at 1 and 5 years, respectively. A high BMI (>25 kg/m2) was consistently associated with elevated odds (between 2- and 5-fold) of worsening patellofemoral and tibiofemoral OA features. CONCLUSION: High rates of degenerative changes occur in the first 5 years after ACLR, particularly the development and progression of patellofemoral cartilage defects. Older patients with a higher BMI may be at particular risk and should be educated about this risk.

Lateral displacement, sulcus angle and trochlear angle are associated with early patellofemoral osteoarthritis following anterior cruciate ligament reconstruction.

PURPOSE: Patellofemoral osteoarthritis (PFOA) occurs in approximately half of anterior cruciate ligament (ACL)-injured knees within 10-15 years of trauma. Risk factors for post-traumatic PFOA are poorly understood. Patellofemoral alignment and trochlear morphology may be associated with PFOA following ACL reconstruction (ACLR), and understanding these relationships, particularly early in the post-surgical time period, may guide effective early intervention strategies. In this study, patellofemoral alignment and trochlear morphology were investigated in relation to radiographic features of early PFOA 1-year post-ACLR. METHODS: Participants (aged 18-50 years) had undergone ACLR approximately 1 year prior to being assessed. Early PFOA was defined as presence of a definite patellofemoral osteophyte on lateral or skyline radiograph. Sagittal and axial plane alignment and trochlear morphology were estimated using MRI. Using logistic regression, the relationship between alignment or morphology and presence of osteophytes was evaluated. RESULTS: Of 111 participants [age 30 ± 8.5; 41 (37%) women], 19 (17%) had definite osteophytes, only two of whom had had patellofemoral chondral lesions noted intra-operatively. One measure of patellar alignment (bisect offset OR 1.1 [95% confidence interval 1.0, 1.2]) and two measures of trochlear morphology (sulcus angle OR 1.1 [1.0, 1.2], trochlear angle OR 1.2 [1.0, 1.5]) were associated with patellofemoral osteophytes. CONCLUSIONS: Patellofemoral malalignment and/or altered trochlear morphology were associated with PFOA 1 year following ACLR compared to individuals post-ACLR without these features. Clarifying the role of alignment and morphology in post-traumatic PFOA may contribute to improving early intervention strategies aimed at secondary prevention. LEVEL OF EVIDENCE: IV.

Accelerated Return to Sport After Anterior Cruciate Ligament Reconstruction and Early Knee Osteoarthritis Features at 1 Year: An Exploratory Study.

BACKGROUND: A timely return to competitive sport is a primary goal of anterior cruciate ligament reconstruction (ACLR). It is not known whether an accelerated return to sport increases the risk of early-onset knee osteoarthritis (KOA). OBJECTIVE: To determine whether an accelerated return to sport post-ACLR (ie, <10 months) is associated with increased odds of early KOA features on magnetic resonance imaging (MRI) 1 year after surgery and to evaluate the relationship between an accelerated return to sport and early KOA features stratified by type of ACL injury (isolated or concurrent chondral/meniscal injury) and lower limb function (good or poor). DESIGN: Cross-sectional study. SETTING: Private radiology clinic and university laboratory. PARTICIPANTS: A total of 111 participants (71 male; mean age 30 ± 8 years) 1-year post-ACLR. METHODS: Participants completed a self-report questionnaire regarding postoperative return-to-sport data (specific sport, postoperative month first returned), and isotropic 3-T MRI scans were obtained. OUTCOME MEASURES: Early KOA features (bone marrow, cartilage and meniscal lesions, and osteophytes) assessed with the MRI OA Knee Score. Logistic regression analyses evaluated the odds of early KOA features with an accelerated return to sport (<10 months post-ACLR versus ≥10 months or no return to sport) in the total cohort and stratified by type of ACL injury and lower limb function. RESULTS: Forty-six (41%) participants returned to competitive sport <10 months post-ACLR. An early return to sport was associated with significantly increased odds of bone marrow lesions (odds ratio [OR] 2.7, 95% confidence interval [CI] 1.3-6.0) but not cartilage (OR 1.2, 95% CI 0.5-2.6) or meniscal lesions (OR 0.8, 95% CI 0.4-1.8) or osteophytes (OR 0.6, 95% CI 0.3-1.4). In those with poor lower limb function, early return to sport exacerbated the odds of bone marrow lesions (OR 4.6, 95% CI 1.6-13.5), whereas stratified analyses for type of ACL injury did not reach statistical significance. CONCLUSION: An accelerated return to sport, particularly in the presence of poor lower limb function, may be implicated in posttraumatic KOA development. LEVEL OF EVIDENCE: IV.

Poor knee function after ACL reconstruction is associated with attenuated landing force and knee flexion moment during running.

PURPOSE: Poor knee function after anterior cruciate ligament reconstruction (ACLR) may increase the risk of future knee symptoms and knee osteoarthritis via abnormal knee joint loading patterns, particularly during high-impact activity. This study aimed to assess the relationship between poor self-reported or clinically measured knee function and knee moments/vertical ground reaction force (vGRF) in individuals following ACLR. METHODS: 61 participants (mean 16.5 ± 3 months following ACLR, 23 women) completed a patient-reported knee function questionnaire and three hop tests (% of uninvolved limb). Participants were divided into satisfactory and poor knee function groups (poor < 85% patient-reported knee function and/or < 85% hop test symmetry). The knee biomechanics of both groups were assessed with three-dimensional motion analysis during the stance phase of overland running at self-selected speeds, and the association between knee function and knee moments was assessed using analysis of covariance with running speed as a covariate. RESULTS: Participants with poor knee function (n = 30) ran with significantly smaller peak knee flexion moments (moderate effect size 0.7, p = 0.03) and significantly smaller peak vGRFs (large effect size 1.0, p = 0.002) compared to those with satisfactory knee function (n = 31). No significant differences were observed for knee adduction and knee external rotation moments or knee kinematics. CONCLUSION: Individuals following ACLR with poor self-reported knee function and/or hop test performance demonstrate knee moments during running that may be associated with lower knee joint contact forces. These findings provide greater understanding of the relationship between knee biomechanics during running and clinical assessments of knee function. LEVEL OF EVIDENCE: III. Cross-sectional study.

Between-leg differences in challenging single-limb balance performance one year following anterior cruciate ligament reconstruction.

Following anterior cruciate ligament (ACL) rupture, reconstructive surgery (ALCR) is often performed to mechanically stabilise the knee, however functional deficits often persist long after surgery. Impaired single-limb standing balance has been observed in the ACLR limb compared to healthy individuals. However, it remains inconclusive as to whether these same balance deficits exist between the injured and contralateral uninjured limbs, during challenging balance tasks, and at a time when patients are permitted to return to sport. 100 adults who had undergone a primary hamstring-tendon ACLR 12 months previously (68 male; median[IQR] age: 28.1[14.1] years) performed tests of single-limb standing with the knee in a functional position of 20-30° flexion, with their eyes closed, over 20s (Nintendo Wii Balance Board). Two repetitions were performed on the ACLR and uninjured limb. Measures of postural control included centre of pressure (CoP) path velocity, anterior-posterior and mediolateral range and standard deviation, and were averaged across the two trials. Wilcoxon signed-rank tests showed no significant between-leg differences in single-limb balance for any of the CoP measures of interest (all P values>0.686). Further, multiple linear regression analyses showed no significant associations between concomitant meniscectomy or chondral lesions noted at the time of ACLR and measures of single-limb balance on the ACLR limb one year later (all P values>0.213). In the context of prior research, these findings suggest bilateral balance deficits may exist prior to ACL injury, or appear post ACL-injury or ACLR. Treatment of balance deficits should therefore consider both limbs after ACLR.

Dynamic Single-Leg Postural Control Is Impaired Bilaterally Following Anterior Cruciate Ligament Reconstruction: Implications for Reinjury Risk.

Study Design Cross-sectional, controlled laboratory study. Background Postural control following anterior cruciate ligament reconstruction (ACLR) primarily has been investigated during static single-leg balance tasks. Little is known about dynamic postural control deficits post-ACLR. Objectives To compare dynamic postural control (bilaterally) in individuals who have undergone ACLR and in healthy controls, and to evaluate the relationship between dynamic postural control and self-reported and objective function. Methods Ninety-seven participants (66 male; median age, 28 years) 12 months post-ACLR and 48 healthy controls (20 male; median age, 30 years) underwent balance assessment using a Nintendo Wii Balance Board during a single-leg squat. Center-of-pressure (CoP) path velocity, as well as CoP amplitude and standard deviation, in both mediolateral (ML) and anteroposterior (AP) directions were recorded. Self-reported function was assessed with the International Knee Documentation Committee Subjective Knee Evaluation Form (IKDC), while hop for distance was used to evaluate functional status. Results Compared to healthy controls, the ACLR group had greater mean CoP path velocity (16% higher, P = .004), ML range (23%, P<.001), ML SD (28%, P<.001), AP range (14%, P = .009), and AP SD (15%, P = .013), indicating worse dynamic balance post-ACLR. Dynamic balance performance was similar between the ACLR limb and the uninjured contralateral limb. The AP SD was weakly associated with hop performance (ß = -.2, P = .046); no balance measures were associated with IKDC score. Conclusion Individuals who have undergone ACLR demonstrate impaired dynamic balance bilaterally when performing a single-leg squat, which may have implications for physical function and future injury risk. Routine dynamic balance assessment may help identify patients who could benefit from targeted neuromuscular training programs to improve objective function and potentially lower reinjury risk. J Orthop Sports Phys Ther 2016;46(5):357-364. Epub 21 Mar 2016. doi:10.2519/jospt.2016.6305.

Predictors and effects of patellofemoral pain following hamstring-tendon ACL reconstruction.

OBJECTIVES: Patellofemoral pain is a frequent and troublesome complication following anterior cruciate ligament reconstruction (ACLR), irrespective of graft source. Yet, little is known about the factors associated with patellofemoral pain following hamstring-tendon ACLR. DESIGN: Retrospective analysis of potential patellofemoral pain predictors, and cross-sectional analysis of possible patellofemoral pain consequences. METHODS: Potential predictors (pre-injury patellofemoral pain and activity level, concomitant patellofemoral cartilage damage and meniscectomy, age, sex, and surgical delay) and consequences (hopping performance, quality of life, kinesiophobia, and return to sport rates and attitudes) of patellofemoral pain 12 months following hamstring-tendon ACLR were assessed in 110 participants using univariate and multivariate analyses. RESULTS: Thirty-three participants (30%) had patellofemoral pain at 12 months post-ACLR. Older age at the time of ACLR was the only predictor of post-operative patellofemoral pain. Following ACLR, those with patellofemoral pain had a higher body mass index, and worse physical performance, quality of life, kinesiophobia and return to sport attitudes. Patellofemoral pain has a significant burden on individuals 12 months following hamstring-tendon ACLR. CONCLUSIONS: Clinicians need to be cognisant of patellofemoral pain, particularly in older individuals and those with a higher body mass index. The importance of considering psychological factors that are not typically addressed during ACLR rehabilitation, such as kinesiophobia, quality of life and return to sport attitudes is emphasised.

Does meniscal pathology alter gait knee biomechanics and strength post-ACL reconstruction?

PURPOSE: Individuals following anterior cruciate ligament reconstruction (ACLR) with concomitant meniscal pathology have a higher risk of developing knee osteoarthritis (OA) compared to those with isolated ACLR. Knee extensor weakness and altered dynamic knee joint biomechanics have been suggested to play a role in the development of knee OA following ACLR. This study investigated whether these factors differ in people following ACLR who have concomitant meniscal pathology compared to patients with isolated ACLR. METHODS: Thirty-three patients with isolated ACLR and 34 patients with ACLR and meniscal pathology underwent strength and gait assessment 12-24 months post-operatively. Primary measures were peak isometric knee extensor torque and knee adduction moment (peak and impulse). Secondary measures included peak knee flexion moment and knee kinematics (sagittal and transverse). RESULTS: There were no between-group differences in knee extensor strength [mean difference (95 % CI) 0.09 (-0.23 to 0.42) Nm/kg, n.s.], peak knee adduction moment [-0.02 (-0.54 to 0.49) Nm/(BW × HT) %, n.s.] or knee adduction moment impulse [0.01 (-0.15 to 0.17) Nm/(BW × HT) %, p = n.s.]. No between-group differences were found for any secondary measures. CONCLUSIONS: No evidence was found to suggest that the higher prevalence of OA in patients with ACLR and meniscal pathology compared to patients with isolated ACLR is attributed to reduced knee muscle strength or altered knee joint biomechanics assessed 1-2 years post-surgery. Given that there is a higher incidence of knee OA in patients with concomitant meniscal pathology and ACLR, further investigation is needed so that population-specific rehabilitation protocols can be developed. LEVEL OF EVIDENCE: III.

Early Patellofemoral Osteoarthritis Features One Year After Anterior Cruciate Ligament Reconstruction: Symptoms and Quality of Life at Three Years.

OBJECTIVE: To determine whether the presence of magnetic resonance imaging (MRI) osteoarthritis (OA) features in the patellofemoral or tibiofemoral joint (i.e., bone marrow lesions, cartilage lesions, and osteophytes) and/or functional impairments, 1 year following anterior cruciate ligament reconstruction (ACLR), can predict Knee Injury and Osteoarthritis Outcome Score (KOOS) at 3 years. METHODS: A total of 93 participants (56 [60%] men, mean ± SD age 29 ± 9 years) who had undergone MRI examination and functional testing at 1-year post-ACLR, completed the KOOS at 3 years postsurgery. Multivariate regression models evaluated the prognostic capacity of compartment-specific osteochondral OA features, scored using the MRI Osteoarthritis Knee Score, and functional performance (hop for distance, 1-leg rise), to predict outcome on 4 KOOS subscales (pain, symptoms, sport/recreation, and quality of life [QOL]). RESULTS: Presence of patellofemoral cartilage lesions 1-year post-ACLR predicted worse score on all KOOS subscales at 3 years (P ≤ 0.01). Regression coefficients (B) were -5.1 (95% confidence interval [95% CI] -9.1, -1.2) for symptoms, -4.0 (95% CI -6.7, -1.4) for pain, -6.7 (95% CI -11.0, -2.4) for sport/recreation, and -8.6 (95% CI -15.1, -2.1) for QOL. No significant associations were found between tibiofemoral MRI features and knee symptoms. Poorer performance on the 1-leg-rise test predicted worse KOOS-QOL (B -6.5 [95% CI -12.4, -0.5], P = 0.03). CONCLUSION: The presence of a patellofemoral articular cartilage lesion and lower 1-leg-rise performance at 1 year postsurgery are prognostic for poorer 3-year outcome following ACLR. Particular attention to patellofemoral compartment lesions and functional capacity is warranted during postoperative rehabilitation programs, as these features represent potential targets for therapy aimed at minimizing symptomatic disease progression in these young adults.

The effects of knee injury on skeletal muscle function, Na+, K+-ATPase content, and isoform abundance.

While training upregulates skeletal muscle Na(+), K(+)-ATPase (NKA), the effects of knee injury and associated disuse on muscle NKA remain unknown. This was therefore investigated in six healthy young adults with a torn anterior cruciate ligament, (KI; four females, two males; age 25.0 ± 4.9 years; injury duration 15 ± 17 weeks; mean ± SD) and seven age- and BMI-matched asymptomatic controls (CON; five females, two males). Each participant underwent a vastus lateralis muscle biopsy, on both legs in KI and one leg in CON. Muscle was analyzed for muscle fiber type and cross-sectional area (CSA), NKA content ([(3)H]ouabain binding), and α1-3 and ß1-2 isoform abundance. Participants also completed physical activity and knee function questionnaires (KI only); and underwent quadriceps peak isometric strength, thigh CSA and postural sway assessments in both injured and noninjured legs. NKA content was 20.1% lower in the knee-injured leg than the noninjured leg and 22.5% lower than CON. NKA α2 abundance was 63.0% lower in the knee-injured leg than the noninjured leg, with no differences in other NKA isoforms. Isometric strength and thigh CSA were 21.7% and 7.1% lower in the injured leg than the noninjured leg, respectively. In KI, postural sway did not differ between legs, but for two-legged standing was 43% higher than CON. Hence, muscle NKA content and α2 abundance were reduced in severe knee injury, which may contribute to impaired muscle function. Restoration of muscle NKA may be important in rehabilitation of muscle function after knee and other lower limb injury.

Patellofemoral osteoarthritis is prevalent and associated with worse symptoms and function after hamstring tendon autograft ACL reconstruction.

OBJECTIVES: To evaluate the compartmental distribution of knee osteoarthritis (OA) after anterior cruciate ligament reconstruction (ACLR), to determine if patellofemoral or tibiofemoral OA is more strongly associated with knee symptoms and function, and to evaluate the contribution of associated injuries and surgical delay to the development of OA. METHODS: This cross-sectional study recruited 70 participants who underwent hamstring tendon (HT) ACLR 5-10 years previously. Radiographic OA was assessed according to the Osteoarthritis Research Society International (OARSI) criteria. Knee symptoms were assessed with the Knee Injury and Osteoarthritis Outcome Score (KOOS) and Anterior Knee Pain Scale (AKPS), while function was assessed with three lower limb tasks (hop-for-distance, one-leg rise and side-hop). Multivariate and binary logistic regression analyses were performed to assess the relationship between OA and symptomatic/functional outcomes and associated injuries/surgical delay, respectively. RESULTS: Radiographic OA was observed in the patellofemoral (47%) and tibiofemoral joints (31%). Pain, symptoms and quality of life on the KOOS and the AKPS were associated with severity of patellofemoral OA (standardised regression coefficient (ß)=-0.3 to -0.5, p=0.001-0.042), whereas only the KOOS-pain subscale was associated with tibiofemoral OA (ß=-0.3, p=0.037). For each functional task, greater patellofemoral OA severity was associated with worse performance, independent of tibiofemoral OA severity (ß=-0.3 to -0.4, p=0.001-0.026). Medial meniscal and patellofemoral chondral lesions at surgery were associated with tibiofemoral and patellofemoral OA development at follow-up, respectively, while a longer surgery delay was associated with patellofemoral OA. CONCLUSIONS: Patellofemoral OA is common following HT ACLR and is associated with worse knee-related symptoms, including anterior knee pain, and decreased functional performance.