Case report: Osteochondral avulsion fracture of the posteromedial bundle of the PCL in knee hyperflexion.

BACKGROUND: Injury of the PCL of the knee in adults usually results in rupture rather than avulsion fracture and avulsions usually occur at the tibial insertion. CASE DESCRIPTION: We report an avulsion of the PCL with a femoral origin in a 22-year-old man who was injured by hyperflexion of the knee and was treated with arthroscopy. There were two parts in the partial osteochondral avulsion fracture of the PCL posteromedial (PM) bundle. One part was fixed with polydioxanone suture through drill holes and the other was removed. The fracture healed after 3 months and the knee was stable. At 11 months postoperatively the patient had returned to full-time work without pain or restrictions. The Lysholm II knee score was 95 points. Physical examination showed a negative posterior drawer sign. LITERATURE REVIEW: We identified four other reported cases of PCL femoral origin avulsion fractures in adults. The subjects were 20 to 25 years old in four of five reports, including our patient. Three of the five patients had involvement of only the lateral cortex of the medial femoral condyle whereas two other patients including our patient, had an osteochondral fracture. The mechanism of PCL avulsion seems to be similar to that of a PCL rupture. PURPOSES AND CLINICAL RELEVANCE: The hyperflexion injury may result in injury of the PM bundle of the PCL. Our case and one other in the literature suggest such avulsions need not involve the entire PCL.