Impact of postoperative isolated patellar chondromalacia on return-to-sport readiness, knee function, and strength following primary anterior cruciate ligament reconstruction: a retrospective comparative study.

Background: The aim of this study was to investigate the association of isolated chondromalacia patella that developed during short-term follow-up after isolated primary anterior cruciate ligament reconstruction (ACLR) on pain, knee function, quality of life, muscle strength, and objective functional performance measures used in return to sport (RTS) assessment. Methods: In the study, 80 male patients who underwent primary ACLR using hamstring autograft were divided into two groups: those who developed chondromalacia in the first year postoperatively (n=40) and those who did not (n=40).Clinical assessment included the Visual Analog Scale (VAS), the International Knee Documentation Committee (IKDC) score, the Lysholm score, and the Tegner Activity Scale; physical function and quality of life were assessed using the Knee Injury and Osteoarthritis Outcome Score - the Knee Outcome Score-Physical Function (KOOS-PS), and the Short Form-12 Health Survey (SF-12) were used Functional performance was assessed using five different Single Leg Hop Tests (SLHT) and isometric dynamometer measurements of knee extensor and flexor muscle strength. Intergroup, inter-side, and group × side interactions were analyzed. Results: Pain levels were significantly higher chondromalacia group, whereas IKDC, Lysholm, KOOS-PS, and SF-12 physical component scores were significantly lower (p < 0.05). No significant differences were found between the groups in terms of Tegner activity level and SF-12 mental health component scores (p > 0.05). In objective assessments related to RTS, medial rotation hop test performance and knee extensor strength were significantly lower in the chondromalacia group (p < 0.05). In both groups, the operated limb demonstrated a significant performance deficit compared with the contralateral limb in all hop tests as well as in knee extensor and flexor strength (p < 0.001). In addition, group × side interaction analyses revealed significant differences associated with the presence of chondromalacia in SLHTs and knee extensor strength (p < 0.001). Conclusions: The development of isolated chondromalacia patella following ACLR is associated with increased pain, impaired knee function, reduced quality of life, weakened quadriceps performance, and inadequate objective RTS criteria. Because this degeneration is a significant prognostic factor that limits functional recovery, patellofemoral health and RTS criteria should be evaluated together during rehabilitation.