Concurrent avulsion of posterior cruciate ligament and semimembranosus: a case-based discussion and literature review.

A 30-year-old male sustained a road traffic accident and presented to our trauma centre with injuries to his pelvis and right knee. Radiology showed closed fractures of the right posterior wall and posterior column of the acetabulum and PCL bony avulsion with posteromedial tibial plateau osteochondral fracture, without any distal neurovascular deficit. He was managed with surgical intervention for both injuries. His hip and knee healed well with a good functional range of motion at 12 months of follow-up. The aim of highlighting this case is that it underscores the rarity of concurrent PCL and semimembranosus (SM) avulsion injuries, emphasizing the importance of comprehensive evaluation and tailored surgical management. Utilizing CT imaging proves instrumental in identifying the associated posteromedial osteochondral fragment. Successful reduction and posterior buttressing of the fragment are crucial for stability against vertical shear forces and subsequent union.