Patella Fracture: Conservative or Surgical Treatment for a Broken Patella

The kneecap (patella) is part of the knee’s extensor mechanism. At the level of the knee joint, it acts as a pulley for the extensor muscles of the lower leg. It is therefore involved in the active extension of the knee joint.

The patella prevents the tendons of the thigh extensor muscles from rubbing directly against the knee joint. It glides along a corresponding groove in the femur.

The mechanism of injury in a patella fracture is usually a fall onto the kneecap or a severe impact trauma.

A patella fracture is accompanied by severe pain on the front of the knee joint and directly over the patella.

Significant swelling of the knee joint usually occurs as well. Typically, the patient is unable to actively extend the lower leg or keep the knee joint extended. A definitive diagnosis can be made using X-rays.

Treatment depends on:

• Type of patella fracture
• Number of fragments
• Alignment of the fracture line and
• the degree of displacement of the fragments

In principle, doctors can treat non-displaced, stable fractures conservatively. Surgical treatment is recommended for displaced, unstable fractures.

Splinting and immobilization of the affected knee joint are always necessary. An increased risk of a blood clot (thrombosis) requires the prophylactic administration of anticoagulants.

As part of surgical treatment, doctors secure the fracture fragments using drill wires or screws. A special bandage absorbs the tensile forces (cerclage). Once the patella fracture has healed, it is usually necessary to remove the implants in a subsequent surgery.

Initially, the knee joint is immobilized using special splints. The patient should not put weight on the leg and should avoid actively extending the knee.

The patient can begin follow-up physical therapy early on:

• pain-managed rehabilitation with full axial weight-bearing in the extended position (Mecron splint)
• X-ray follow-up after weight-bearing and after 14 days to rule out secondary dislocation
• Range of motion restrictions: Weeks 1–3: Ext/Flex 0–0–30; Weeks 4–6: Ext/Flex 0–0–60

Mobilization following surgical treatment depends on the extent of the injury and the surgical procedure. Osteosynthesis with screws and tension straps can usually also be mobilized according to the following schedule:

• Weeks 1–3: Extension/Flexion 0–0–30
• Weeks 4–6: Extension/flexion 0–0–60

The use of a continuous passive motion (CPM) device is helpful. When bearing full axial weight, the patient must use forearm crutches for gait training. This allows the patient to relieve pressure on the extensor mechanism and reduce retropatellar compression.

The prognosis for an uncomplicated patella fracture is usually very good. The patient can use the affected leg without restriction.

Occasionally, residual symptoms such as a tendency to swell or sensitivity to weather changes may occur and can persist for several months.

A long-term complication may be premature joint wear in the patellar glide surface. This occurs when, following comminuted fractures, an irregularity in the cartilage on the back of the patella persists despite surgery.

Initial and postoperative local and systemic analgesic therapy should be administered.

If a patellar fracture is suspected, a clinical examination should be performed promptly to identify a fracture of the patella and possible injuries to the quadriceps tendon or extensor mechanism in a timely manner. The exact characterization and classification of the injury is determined using X-rays or computed tomography (CT), particularly if displacement of the fracture fragments or involvement of the articular surface is suspected.

Treatment of a patellar fracture can be conservative or surgical; however, minimally displaced distal pole fractures often heal without surgery. For unstable fractures, procedures such as tension band osteosynthesis or cerclage are used as part of surgical management to prevent the fragments from diverging. Early treatment following a fall on the knee or a traffic accident is crucial for the healing and management of a patellar fracture, so that long-term issues such as pain on the front of the knee, difficulty climbing stairs, a bent knee joint, or joint wear can be avoided, and the knee does not remain actively restricted.