Intra-Articular Dislocation of the Patella With Associated Hoffa Fracture in a Skeletally Immature Patient.

Since 1887, approximately 50 cases of an intra-articular patellar dislocation have been reported in the worldwide literature. The vast majority of patients required an open reduction of the patella or closed reduction under general anesthesia. This injury has never been reported in association with a coronal shear fracture of the femoral condyle. A 14-year-old boy presented to our institution with his left knee locked in flexion after a direct blow. Radiographs showed the patella rotated on its horizontal axis and lying in a transverse position within the knee joint, as well as a concomitant femoral condyle fracture. After a successful closed reduction of the patella, the patient underwent open reduction and rigid fixation of the femoral condyle fracture with countersunk interfragmentary screws. At 12 months, the patient was ambulating on the left leg and had painless motion of the knee. We present a rare injury pattern in a skeletally immature patient after a direct blow to the knee. By treating the injuries in a sequential manner and providing a stable fixation construct, the patient was able to achieve a satisfactory return to function even after sustaining a considerable injury to the knee.