A patella fracture is a break in the kneecap, typically from a direct blow to the front of the knee or a forceful quadriceps contraction against resistance. Patellar fractures can disrupt the extensor mechanism and affect the articular cartilage behind the kneecap. Treatment depends on the fracture pattern, degree of displacement, and whether the extensor mechanism remains intact.
What Is a Patella Fracture?
The patella is a sesamoid bone embedded within the quadriceps tendon, functioning as a pulley that increases the mechanical advantage of the quadriceps during knee extension. Its back surface is covered with articular cartilage that glides against the trochlear groove of the femur.
Patella fracture patterns include:
- Transverse fractures: horizontal break across the mid-patella, typically from eccentric quadriceps contraction
- Stellate fractures: multiple fragments from a direct blow to the front of the knee
- Vertical fractures: often stable and non-displaced
- Lower pole fractures: avulsion of the inferior pole with the patellar tendon still attached
- Open fractures: bone exposed through the overlying skin, a surgical urgency
The critical clinical question is whether the extensor mechanism is disrupted. A fracture with intact active knee extension may be treated non-surgically. A fracture with loss of active extension has functionally the same effect as a patellar tendon or quadriceps tendon rupture and requires surgical fixation.
Causes and Risk Factors
- Direct blow to the front of the knee (fall, dashboard injury, sports collision)
- Forceful eccentric quadriceps contraction against a flexed knee
- Falls onto a flexed knee on hard surface
- Osteoporosis and low bone density in older patients
- Sports with high-velocity impact potential
Symptoms
- Immediate pain and swelling at the front of the knee
- Visible deformity or gap at the patella in displaced fractures
- Inability to actively extend the knee or lift a straight leg when the extensor mechanism is disrupted
- Difficulty bearing weight
- Bruising and abrasion over the front of the knee
Diagnosis
Dr. Chudik’s evaluation includes the mechanism, the timing, and a physical examination focused on active knee extension. Inability to maintain a straight leg against gravity indicates extensor mechanism disruption regardless of the fracture appearance on X-ray. Open wounds over the patella are carefully documented for open fracture criteria. X-rays in multiple views define the fracture pattern. CT is occasionally added for complex multifragmentary patterns. The Westmont office has on-site high-field MRI and X-ray.
Treatment
Non-surgical treatment is appropriate for non-displaced fractures (less than 2 to 3 mm displacement) with intact extensor mechanism. It involves:
- Immobilization in a knee brace or cast in extension for three to six weeks
- Progressive range of motion beginning at three to four weeks
- Gradual weight-bearing and strengthening
- Return to activity over two to three months
Surgical treatment is indicated for displaced fractures, for any fracture with extensor mechanism disruption, and for open fractures. Dr. Chudik performs open reduction and internal fixation, using tension band wiring, screws, or plate fixation depending on the fracture pattern. In severely comminuted lower pole fractures, partial patellectomy with repair of the patellar tendon is performed. Total patellectomy is avoided whenever possible because it weakens the extensor mechanism significantly.
Recovery and Outcomes
Recovery after internal fixation typically includes brace immobilization in extension for two to four weeks with early gentle range of motion, progressive motion and weight-bearing over the following month, and strengthening over three to four months. Return to sport is typically four to six months.
Outcomes are generally good when the fracture is anatomically reduced and the extensor mechanism is restored. Complications include hardware irritation (often requiring removal after healing), stiffness, and, in severely comminuted fractures, post-traumatic patellofemoral arthritis.
When to See Dr. Chudik
Schedule urgent evaluation after any direct blow to the knee that produces severe pain, visible deformity, or inability to lift a straight leg. Open wounds over the patella require emergency evaluation. Call 630-324-0402 or request an appointment online.