Comparison of lower limb alignment in knees with and without patellar tendinopathy among elite volleyball players: a cross-sectional study

Patellar tendinopathy is a prevalent overuse injury in sports requiring rapid force production by the knee extensors and is particularly common among elite volleyball players. This study aimed to compare lower-limb frontal-plane alignment between knees with and without patellar tendinopathy in elite volleyball athletes. We conducted a cross-sectional descriptive study among 22 elite male volleyball players from Alborz Province, selected through purposive sampling. We diagnosed patellar tendinopathy using the Royal London Hospital Test (RLHT). Standardized weight-bearing radiographs of the lower limbs were obtained. Seven anatomical and mechanical alignment parameters, including anatomical Lateral Distal Femoral Angle (aLDFA), mechanical Lateral Distal Femoral Angle (mLDFA), anatomical Medial Proximal Tibial Angle (aMPTA), mechanical Medial Proximal Tibial Angle (mMPTA), anatomical TibioFemoral Angle (aTFA), anatomical Lateral Distal Tibial Angle (aLDTA), and mechanical Lateral Distal Tibial Angle (mLDTA), were measured. Normality was assessed using the Shapiro–Wilk test. Considering the normal distribution of the data, paired t-tests were employed to compare alignment measures between affected and unaffected knees. Statistical significance was set at p ≤ 0.05, and analyses were performed using SPSS version 26. No significant differences were observed between knees with and without patellar tendinopathy ( p ≥ 0.05) across any of the measured anatomical or mechanical alignment parameters, including aLDFA, mLDFA, aMPTA, mMPTA, aTFA, aLDTA, and mLDTA. These findings indicate that patellar tendinopathy in elite volleyball players is unlikely to be associated with static frontal-plane lower-limb alignment. Rather, functional and dynamic biomechanical factors may play a more prominent role in the onset and progression of the condition. Thus, future clinical and research efforts should prioritize training load regulation and movement pattern correction rather than relying solely on static alignment evaluations.