Incarcerated patellar tendon in Hoffa fracture: an unusual cause of irreducible knee dislocation.

Irreducible knee dislocation due to incarcerated soft tissue structures in associated fractures is extremely uncommon. We report a case of irreducible, closed dislocation of the knee secondary to incarcerated patellar tendon in a Hoffa fracture (unicondylar fracture of femur in the coronal plane) with associated communited fracture of patella and disruption of both cruciates. We treated this case initially with open reduction and internal fixation of fracture and repair of the patellar tendon. During the total followup period of eighteen months, the patient had restricted joint range of motion with no joint instability despite aggressive physiotherapy and further surgical intervention. The prognosis of such complex knee injuries with combination of ligamentous injuries and associated fractures is much worse when compared to either injuries alone.