Patellar Fracture Non-Union with Acquired Patella Baja: A Case Report

Abstract

Fractures of the patella are usually caused by direct forces on the bone such as from a fall on a flexed knee or a dashboard injury and constitute 1% of all fractures 1,9. This injury occurs most commonly in males (2:1 ratio) and may disrupt the extensor mechanism affecting ambulation. On physical exam a patient presenting with a patellar fracture will have significant hemarthrosis with anterior knee pain, inability to perform a straight leg test, and a palpable patellar defect. X-rays of this pathology are best evaluated on lateral x-ray. Operative fixation is commonly performed in order to preserve the patella and maintain full range of motion of the knee. Non-union of patellar fractures following surgical fixation is a rare complication; a recent meta-analysis reported an incidence of 1.3% 1,9. The literature on the treatment of patellar fracture non-unions is limited to small case series. Patellabajais a condition in which the patella lies lower than normal in relation to the tibial tubercle. Diagnosis involves radiographs of the knee and measurement of the patella tendon length in relation to the patella bone length, known as the Insall-Salvatiratio 2,9. This condition is commonly seen following surgery or after trauma. These cause the patellar tendon to lose length, either from scarring or shrinkage of fibers. Symptoms may include anterior knee pain stiffness in addition to weakness the extensor mechanism and restriction of full knee flexion 2,9. Depending on the functional demands of the patient and severity of the symptoms, patients can either be managed non-operatively or with surgery to modify patella positioning or with patellectomy in severe cases. To the best of our knowledge there is no previous literature describing the treatment of a patellar nonunion with significant patella baja. We present the case of a patella fracture nonunion that failed previous surgical fixation and acquired patella baja, which we treated with repeat open reduction internal fixation and tibial tubercle osteotomy.