Traumatic separation of a bipartite patella

Abstract

A 62-year-old man fell downsfairs sustaining a hyperflexion injury to his left knee. The knee became swolleti immediately. The patient noticed that he could not raise his leg straight and had a ‘weakness’ of the leg. He presented to hospital 8 weeks after the injury, having cycled to the consultation. Examination revealed a swelling in the suprapatellar region of his left knee and no active extension of the knee. There was thought to be a palpable gap immediately above the patella. The patient had sustained an injury to his left knee 43 years previously, but had been asymptomatic for 40 years. In 1980 a radiograph of the left knee showed mild medial compartment osteoarthritis and a bipartite patella. A diagnosis of a rupture of the quadriceps tendon was made. He was admitted to hospital 5 days later for repair of the rupture of the quadriceps tendon. At admission the patient was able to raise his leg straight with a 5” lag and climb stairs unaided. Isometric contra&ion of the quadriceps resulted in proximal movement of the left patella. The only other loss of function was an inability to stand unaided on his left leg. A radiograph revealed that the previously noted bipartite patella had separated along the line of fibrocartilage that had previously joined the two parts of the bipartite patella (Fig .I). The patient was therefore treated in a plaster cylinder in the hope that there would be a further return of function. When the plaster was removed after 4 weeks there was some wasting of the quadriceps, a moderate effusion of the knee and an active range of movements from 5” to 90” of flexion. There were no areas of tenderness and the patient was able to stand on the affected leg without support. Physiotherapy directed at regaining knee movement and exercising the quadriceps was started. At review 3 months from presentation, the patient was free from pain, had a range of movement from 5” of fixed flexion to 120”.