The patella, or kneecap, sits within the tendon that straightens the knee. It usually breaks from a direct blow or a fall onto the front of the knee. Because the kneecap is part of the straightening mechanism, the most important question is whether the knee can still actively straighten.
When the fragments stay aligned and the straightening mechanism is intact, many patella fractures heal without surgery. When the fragments are displaced or the knee cannot straighten, surgery restores the alignment and the mechanism.
Symptoms
Common findings after a blow or fall include:
- Pain and swelling over the front of the knee
- Difficulty or inability to straighten the knee or keep it straight
- A palpable gap in the kneecap
- Bruising and tenderness directly over the patella
How it is diagnosed
X-rays confirm the fracture and how displaced it is, and the exam tests whether the knee can actively straighten. Sometimes a CT scan adds detail for surgical planning. Whether the straightening mechanism is intact is what drives the decision.
Dr. Lee's central question is whether the knee can straighten and whether the fragments are aligned. A non-displaced fracture with an intact straightening mechanism is treated without surgery, immobilized briefly and then moved early to limit stiffness.
Displaced fractures, and any fracture where the knee cannot straighten, are fixed surgically, restoring the alignment and the extensor mechanism with a tension-band or screw-and-plate construct. Early protected motion follows to protect against the stiffness the knee is prone to after immobilization.
Non-surgical treatment
A non-displaced patella fracture with an intact ability to straighten the knee is treated in a brace initially locked in extension, with motion introduced as healing allows to avoid stiffness.
Surgical treatment
Displaced fractures, and fractures that disrupt the ability to straighten the knee, are fixed surgically to restore the kneecap's alignment and the straightening mechanism. Secure fixation allows protected motion to start early.
Recovery timeline
Recovery balances protection with early motion:
- Weeks 0 to 2Brace. Weight-bearing as directed with the brace locked in extension.
- Weeks 2 to 6Progressive range of motion can sometimes be started 4-6 weeks from the injury date. Brace is still on during this time, and is progressively unlocked.
- Weeks 6 to 12Strengthening and a graded return to activity as the fracture heals. Brace is slowly weaned off and is activity dependent.
What patients commonly misunderstand
Two questions that drive the plan:
- Can you straighten the knee? The ability to actively straighten the knee is the key question with a kneecap fracture. If it is lost, the straightening mechanism is disrupted and surgery is usually needed.
- Early motion limits stiffness. As with the elbow, the knee stiffens when held still too long. For stable fractures and after fixation, early protected motion is what protects function.
This page is general educational content authored by Dr. Lee. It is not a substitute for individual medical advice. Every patient's case is different, book a consultation to discuss yours.