Peroneus longus autograft in anterior cruciate ligament reconstruction impairs ankle strength, balance and jump performance despite preserved knee function: a one year comparative study.

PURPOSE: This study aimed to comprehensively compare the effects of peroneus longus tendon (PLT) and semitendinosus tendon (ST) autografts on knee and ankle isometric strength asymmetries, jump performance, postural stability, and patient-reported outcome measures (PROMs) in patients 12 months after isolated anterior cruciate ligament reconstruction (ACLR). METHODS: In this retrospective study, 98 eligible patients underwent propensity score matching. After dropouts, 60 patients (ST: n = 30; PLT: n = 30) were evaluated 12 months postoperatively. Clinical outcomes were assessed using the International Knee Documentation Committee (IKDC), Lysholm, Tegner, and American Orthopaedic Foot and Ankle Society (AOFAS) scales. Functional assessments included single-leg hop tests (SLHTs), countermovement jump (CMJ), drop jump (DJ), single-leg jump (SLJ), single-leg drop jump (SLDJ), land-and-hold (LH), and single-leg stance (SLS) tests. Isometric strength for knee flexion/extension and ankle plantar flexion/eversion was measured. Two separate 2 × 2 mixed-design ANOVAs were utilized to evaluate time-dependent and inter-limb (operative vs. contralateral) differences across groups. RESULTS: Both groups demonstrated significant time-dependent improvements in IKDC, Lysholm, and Tegner scores (p < 0.05), with no significant inter-group differences. However, the PLT group showed significantly higher inter-limb functional asymmetry in SLHTs (14.06%-21.34%) compared to the ST group (3.95%-7.85%). Significant group × limb interactions were observed for knee extension strength (p = 0.025), along with considerable deficits in ankle plantar flexion (p < 0.001) and eversion (p < 0.001) strengths specifically in the PLT group. Inter-limb asymmetry in jump height and landing force was considerably more pronounced in the PLT group in all vertical jump variations. Furthermore, the PLT group showed significantly impaired dynamic stabilization, with longer time to stabilization (TTS) and increased anterior-posterior postural sway during LH and SLS (p < 0.05). CONCLUSIONS: While subjective clinical scores are comparable, PLT autografts result in significant donor-site strength deficits and increased inter-limb functional asymmetry at the 12-month follow-up. These functional deficits suggest that PLT autografts should be used with caution, particularly in athletes who depend on optimal ankle stability for athletic performance.