Changes in Quadriceps Rate of Torque Development After Anterior Cruciate Ligament Reconstruction and Association to Single-Leg Hop Distance.

BACKGROUND: Quadriceps neuromuscular function is negatively affected after anterior cruciate ligament reconstruction (ACLR). The specific effect that the ACLR has on the quadriceps femoris rate of force production and its impact on functional recovery is unknown. HYPOTHESIS: The anterior cruciate ligament (ACL) limb would present persistent deficits in the rate of torque development (RTD), when compared with the non-ACL limb before ACLR until 9 months (9M) post-ACLR. STUDY DESIGN: Prospective cohort study. LEVEL OF EVIDENCE: Level 3. METHODS: Twenty-eight participants performed quadriceps maximum voluntary isometric contractions (MVICs) before (PRE), at 5 months (5M) and at 9M after ACLR. Single-leg hop distance was also assessed at 9M. Quadriceps RTD was calculated at 50, 100, and 200 ms after the onset of torque production. Maximum RTD was also calculated. A 2 (limb) × 3 (time) repeated-measures analysis of variance was used for RTD50, RTD100, RTD200, and RTDmax. Linear regressions were used to evaluate the associations of MVIC and RTD values at 5M and 9M with single-leg hop distance at 9M. RESULTS: The ACL limb had lower RTD values at all times compared with the non-ACL limb (P < 0.05). RTD of the ACL limb significantly decreased from PRE to 5M, and then recovered to PRE levels at 9M (P < 0.05). The non-ACL limb displayed no differences from baseline to either 5M or 9M. MVIC and RTD200 at 5M predicted (R2 = 0.313 and R2 = 0.262, respectively) single-leg hop distance at 9M, better than the strength and RTD at 9M (R2 = 0.235 and R2 = 0.128, respectively). CONCLUSION: Quadriceps RTD is negatively affected after ACLR, and deficits may persist at the time of return to activity. Strength and RTD during recovery at 5M may predict more than 25% of the variance in single-leg hop distance at 9M, independently; hence, both provide important information to monitor functional recovery post-ACLR. CLINICAL RELEVANCE: RTD should be measured to understand the changes in neuromuscular capacity after ACLR, and rehabilitation strategies that target quick force production, ie, quick muscle activation and functional tasks, should be implemented.

Self-reported bio-psycho-social factors partially distinguish patellar tendinopathy from other knee problems and explain patellar tendinopathy severity in jumping athletes: A case-control study.

OBJECTIVE: To determine what combinations of self-reported factors distinguish patellar tendinopathy (PT) from other knee problems, and explain PT severity variance. DESIGN: Case-control study. SETTING: Social media, private practice and National Health Service. PARTICIPANTS: An international sample of jumping athletes diagnosed with either PT (n = 132; 30.7 ± 8.9 years; 80 males; VISA-P = 61.6 ± 16.0) or another musculoskeletal knee condition (n = 89; 31.8 ± 9.9 years; 47 males; VISA-P = 62.9 ± 21.2) by a clinician in the last 6 months. MAIN OUTCOME MEASURES: We considered clinical diagnosis (case = having PT vs control = having other knee problems) as the dependent variable. Severity and sporting impact were defined by VISA-P and availability, respectively. RESULTS: A model comprising seven factors distinguished PT from other knee problems; training duration (OR = 1.10), sport type (OR = 2.31), injured side (OR = 2.28), pain onset (OR = 1.97), morning pain (OR = 1.89), condition acceptability (OR = 0.39) and swelling (OR = 0.37). Sports-specific function (OR = 1.02) and player level (OR = 4.11) explained sporting availability. 44% of PT severity variance was explained by quality of life (ß = 0.32), sports-specific function (ß = 0.38) and age (ß = -0.17). CONCLUSION: Sports-specific, biomedical and psychological factors partially distinguish PT from other knee problems. Availability is mainly explained by sports-specific factors, while psychosocial factors impact on severity. Adding sports-specific and bio-psycho-social factors into assessments could help better identification and management of jumping athletes with PT.

Neuromuscular joint function in knee osteoarthritis: A systematic review and meta-analysis.

BACKGROUND: Neuromuscular alterations are common in people with knee osteoarthritis (KOA). A comprehensive understanding of these alterations is important to enable targeted rehabilitation strategies. OBJECTIVES: This systematic review and meta-analysis aimed to comprehensively understand the neuromuscular alterations around the knee joint in people with KOA. METHODS: Moderate- and high-quality studies based on a modified version of the Downs and Black checklist, comparing neuromuscular function of peri­articular muscles between people with KOA and controls were retrieved from five databases from inception to October 2020. Outcomes included normalized isokinetic strength, muscle size, voluntary activation, cortical and spinal-reflex excitability, and torque-related outcomes. Data were pooled according to structural KOA severity with sensitivity analysis based on sex. Evidence levels are presented in evidence gap maps. RESULTS: A total of 7 high-quality and 22 moderate-quality studies were retained (1146 people with KOA and 1353 age- and sex-matched controls). Studies demonstrated quadriceps and hamstring strength deficits and increased hamstring-to-quadriceps strength ratios across KOA severities. Women presented lower quadriceps strength at early KOA (very limited evidence) and lower voluntary activation at end stage KOA (very limited evidence) as compared with controls, whereas men did not (moderate evidence). People with KOA also demonstrated lower quadriceps force control ability with no change in rapid force production (very limited evidence). Voluntary activation deficits for quadriceps were evident (moderate evidence), with no change in quadriceps cortical excitability (very limited evidence) or soleus spinal reflexes (very limited evidence). No muscle size change was demonstrated except for the vastus medialis (limited evidence). Evidence gaps were found for neural and torque-related measures and differences in hamstring, gastrocnemius, soleus, and popliteus. CONCLUSIONS: Neuromuscular deficits are evident across different structural KOA severities and are seen in muscle strength, voluntary activation, muscle size, and force control ability. Women may exhibit these alterations to a greater extent than men. PROSPERO REGISTRATION NUMBER: CRD42019160845.

Variation in Patient-Reported Outcomes in Young and Old Patients Up to 4 to 6 Years After Arthroscopic Partial Meniscectomy.

OBJECTIVE: To assess the variation in changes in patient-reported outcomes 4 to 6 years after arthroscopic partial meniscectomy (APM). DESIGN: Prospective cohort study. SETTING: Orthopedic departments at public hospitals. PATIENTS: Patients (n = 447) from the Knee Arthroscopy Cohort Southern Denmark undergoing APM. INTERVENTIONS: All patients underwent APM. MAIN OUTCOME MEASURES: Change in KOOS4 scores from baseline before surgery to ∼5 years (range 4-6 years) after surgery. KOOS4 is the average aggregated score of 4 of 5 of the Knee injury and Osteoarthritis Outcome Score (KOOS) excluding the activities of daily living subscale (minimal clinical important improvement ∼10 points). A mixed linear model adjusted for sex and body mass index was used to assess change from baseline to ∼5-year follow-up. Change in KOOS4 was divided into 5 categories based on change from baseline to ∼5-year follow-up: <0 points, 0 to 9 points, 10 to 19 points, 20 to 29 points, and ≥30 points. RESULTS: On average, patient-reported outcomes continued to improve from baseline to ∼5-year follow-up (mean KOOS4 change: 26, 95% CI, 24-28). Proportions in the different response groups were <0 points (12%), 0 to 9 points (13%), 10 to 19 points (16%), 20 to 29 points (19%), and ≥30 points (40%), with no difference between younger (≤40 years, n = 75) and older (>40 years, n = 337) patients (P = 0.898). CONCLUSIONS: Patient-reported outcomes on average improved up to ∼5 years after APM; however, large variability was observed. The similar variability in younger and older patients questions the assumption that younger patients with traumatic injuries experience larger benefits from APM.

Neuromuscular Function of the Knee Joint Following Knee Injuries: Does It Ever Get Back to Normal? A Systematic Review with Meta-Analyses.

BACKGROUND: Neuromuscular deficits are common following knee injuries and may contribute to early-onset post-traumatic osteoarthritis, likely mediated through quadriceps dysfunction. OBJECTIVE: To identify how peri-articular neuromuscular function changes over time after knee injury and surgery. DESIGN: Systematic review with meta-analyses. DATA SOURCES: PubMed, Web of Science, Embase, Scopus, CENTRAL (Trials). ELIGIBILITY CRITERIA FOR SELECTING STUDIES: Moderate and high-quality studies comparing neuromuscular function of muscles crossing the knee joint between a knee-injured population (ligamentous, meniscal, osteochondral lesions) and healthy controls. Outcomes included normalized isokinetic strength, muscle size, voluntary activation, cortical and spinal-reflex excitability, and other torque related outcomes. RESULTS: A total of 46 studies of anterior cruciate ligament (ACL) and five of meniscal injury were included. For ACL injury, strength and voluntary activation deficits were evident (moderate to strong evidence). Cortical excitability was not affected at < 6 months (moderate evidence) but decreased at 24+ months (moderate evidence). Spinal-reflex excitability did not change at < 6 months (moderate evidence) but increased at 24+ months (strong evidence). We also found deficits in torque variability, rate of torque development, and electromechanical delay (very limited to moderate evidence). For meniscus injury, strength deficits were evident only in the short-term. No studies reported gastrocnemius, soleus or popliteus muscle outcomes for either injury. No studies were found for other ligamentous or chondral injuries. CONCLUSIONS: Neuromuscular deficits persist for years post-injury/surgery, though the majority of evidence is from ACL injured populations. Muscle strength deficits are accompanied by neural alterations and changes in control and timing of muscle force, but more studies are needed to fill the evidence gaps we have identified. Better characterisation and therapeutic strategies addressing these deficits could improve rehabilitation outcomes, and potentially prevent PTOA. TRIAL REGISTRATION NUMBER: PROSPERO CRD42019141850.