Reconstruction of a Rare Split-Level Bilaminar Patellar Tendon Rupture With Concomitant Multiligament Knee Injury Using Peroneus Longus Autograft: A Case Report.

Abstract

Introduction: Patellar tendon ruptures (PTRs) are critical causes of knee extensor mechanism failure. Although typically isolated, a split-level bilaminar rupture pattern, in which different layers of the PTR at different anatomical levels, is extremely rare in adults, particularly when associated with complex multiligamentous injuries (occurring in only 0.02%-0.2% of orthopedic cases).

Case presentation: A 60-year-old female presented with acute knee pain and loss of active extension following a fall. Clinical examination revealed patella alta and a palpable infrapatellar gap. Imaging confirmed a full-thickness PTR, a medial femoral condyle avulsion fracture (MCL attachment), and a fibular head fracture (PLC injury-variant). Intraoperatively, a split-level bilaminar PTR and a complete midsubstance ACL (anterior cruciate ligament) rupture were identified. The injury was managed through primary repair augmented with a peroneus longus tendon (PLT) autograft to provide early mechanical stability and protect secondary stabilizers during healing.

Discussion: A split-level bilaminar PTR in adults with concomitant multiligamentous injury is a rare clinical entity that requires high diagnostic suspicion. In this case, PLT augmentation provided a robust construct for extensor mechanism reconstruction while preserving the hamstring tendons and allowing good functional outcomes.

Conclusion: In this case, anatomical repair augmented with a peroneus longus autograft resulted in restoration of the extensor mechanism at the 6-month postoperative follow-up while preserving the hamstring tendons.