The patella, or kneecap, sits in front of the knee joint and protects it while helping the thigh muscles extend the leg. Patella fractures often occur from a direct blow to the knee—such as falling directly on it—or from sudden, forceful contraction of the thigh muscle.

Treatment depends on whether the bone fragments are still in place. If the fracture is small and the pieces are not separated, and the patient can still straighten their leg the knee can be kept straight in a brace or cast for 4–6 weeks. The patient may be allowed to put some weight on the leg while walking with crutches. If the bone is broken into pieces or the patient cannot straighten the leg, surgery is needed. This usually involves using wires, screws, or plates to hold the bone together while it heals. After surgery, movement exercises start early to avoid stiffness, but full weight-bearing is delayed until the bone is strong enough.

Watch video of Fractures of the Patella

Potential complications include knee stiffness, muscle weakness, and—in adults—arthritis in the knee if the fracture involves the joint surface. Early diagnosis, proper immobilization or surgical repair, and guided rehabilitation greatly improve outcomes.