Patellafraktur

Patellafraktur, or patellar fracture, is a break of the patella, the kneecap. It most commonly results from direct trauma to the knee (such as a fall onto the knee or a dashboard injury) or from a strong, sudden contraction of the quadriceps with the knee flexed. Fractures are classified by pattern (transverse, vertical, comminuted) and by displacement (displaced vs nondisplaced) and may involve disruption of the extensor mechanism.

Clinical presentation includes knee pain and swelling, difficulty or inability to straighten the leg, and often a palpable defect or gap over the patella. The extensor mechanism may be impaired, and there can be palpable crepitus or instability. Initial assessment should include neurovascular examination of the leg and imaging.

Diagnosis relies on radiographs of the knee, typically including anteroposterior, lateral, and a specific skyline or tangential view to assess the patellofemoral joint. In complex or intra-articular fractures, computed tomography can delineate fracture fragments and aid planning. Magnetic resonance imaging may be used to evaluate associated soft-tissue injuries.

Treatment is guided by fracture type and extensor mechanism integrity. Nondisplaced or minimally displaced fractures with an intact extensor mechanism are usually treated nonoperatively with immobilization in extension for about 4 weeks, followed by gradual rehabilitation and progressive strengthening. Displaced fractures or those with extensor mechanism disruption generally require surgery. Common techniques include tension-band wiring or screw fixation to restore the articular surface and extensor function. In elderly patients with comminution, partial patellectomy or other reconstruction may be considered.

Prognosis is generally favorable with appropriate management, but complications can include knee stiffness, maltracking, posttraumatic osteoarthritis, hardware irritation, and, less commonly, infection. Rehabilitation focuses on restoring range of motion, quadriceps strength, and gradual return to weight-bearing.