Factors associated with anterior knee pain 12 months follow hamstring tendon autograft ACL reconstruction

Abstract

Introduction: Anterior knee pain (AKP) is a common and troublesome complication following anterior cruciate ligament reconstruction (ACLR), irrespectiveof graft source.WhileAKP is frequently associated with harvest-site morbidity after bone-patellar tendon-bone autograft ACLR, factors associatedwith AKP following the common hamstring-tendon (HT) autograft are not known. Methods: 110 participants (76 males, mean age 30±8 years) were consecutively recruited 12 months following a primary HT autograft ACLRbyoneof twoorthopaedic surgeons. All participants underwent assessment of physical performance (hop-for-distance [HFD], cross-over HFD, side-hop and one-leg rise tests) and patient-reported outcomes including quality of life (QoL) (EQ5D), kinesiophobia (Tampa Scale), activity level (Tegner), return to sport and attitudes related to return to sport (ACL-return to sport index). Impairments in knee range of movement, laxity, frontal plane alignment and hip external rotation strength were recorded, while injuries to menisci and patellofemoral cartilage were noted intra-operatively. Clinical andphysical performancedatawerenormalised to the uninjured limb. K-means cluster analysis classified participants into those with and without AKP using the validated Kujala Patellofemoral Score (0–100). Analysis of variance was used to evaluate differences between AKP and no AKP groups (p<0.05). Results: Thirty-three participants (30%) were defined as having AKP from the cluster analysis (Kujala score ≤87/100). Those with AKP were of older age (mean difference 4.4 years, 95% confidence interval 1.0–7.9), had a higher body mass index (2.3 kgm−2, 0.7–3.8), performed between 8% and 25% worse on the HFD, crossoverHFDandone-leg rise tests, andhad lower activity level (Tegner median 4 vs 6). The presence of AKPwas also associatedwithworse QoL, kinesiophobia and return to sport attitudes. No clinical or intra-operative features of AKP were identified. Discussion:TheprevalenceofAKPweobserved is similar topreviously reported rates following HT autograft ACLR. Importantly, our findings reveal that AKP is not simply a trivial complication following HT harvest. Sports medicine clinicians need to be cognisant of AKP in this population as it is associatedwithworse scores on both patient-reported outcomes and physical performance. For those with AKP following ACLR, rehabilitation protocols should include a greater focus onweightmanagement education, progression of rehabilitation to high-level activities, including adequate functional retraining to optimise confidence and return to sport attitudes. While not being causally determined, these strategies may help minimise the high prevalence of AKP and the significant burden it places on this population.