Overview
The patella, or kneecap, is a sesamoid bone, meaning a bone embedded within a tendon rather than connected to the skeleton by a joint in the usual way. It sits inside the shared tendon formed by the quadriceps muscle above and the patellar tendon below, and it acts as a pulley: by holding the tendon away from the joint, it gives the quadriceps more leverage and makes straightening the knee far easier. The back surface of the patella is covered in cartilage and glides against the front of the femur (femur) with every step.
When the patella fractures and the fragments separate, the extensor mechanism, the system that straightens the knee, is disrupted. The quadriceps can no longer generate enough force to lift the leg with the knee extended against gravity. This loss of active extension is the clearest clinical sign that surgery is needed. A patella that has cracked but has not separated, and where the patient can still lift the leg fully extended, may be manageable in a brace.
Patella fractures most often happen from a direct blow to the front of the knee (a dashboard injury, a fall onto a hard surface) or from a sudden, forceful quadriceps contraction that pulls the bone apart. Older patients with thinner bone can fracture the patella from a relatively low-energy fall. Some fractures are a clean two-piece split; others are comminuted, meaning shattered into multiple fragments, which makes reconstruction technically more demanding.
Open reduction and internal fixation (ORIF) of the patella restores the bone's shape, repairs the extensor mechanism, and holds everything together while healing occurs. The specific hardware used, whether tension-band wiring, screws, or a combination, depends on the fracture pattern. The goal is fixation stable enough to allow early knee bending within the first few days, since prolonged immobilization leads to stiffness in the quadriceps and the joint itself.
Why it's done
Patella ORIF is typically considered when imaging and the clinical picture together indicate that the fracture will not reliably heal or function without surgical stabilization. Common indications include:
Loss of active knee extension
If you cannot lift the leg with the knee held straight, the extensor mechanism is no longer working. This is the key clinical indication for surgery.
Separated fragments
Once the pieces pull apart, the constant pull of the quadriceps keeps drawing them farther apart.
A step in the joint surface
The back of the patella is a joint surface that glides against the femur with every bend of the knee, so it needs to be lined back up.
Open fracture
A fracture that breaks through the skin needs urgent cleaning of the wound (debridement) and fixation.
How it works
Simple transverse fractures are typically fixed with two cannulated (hollow) screws and a figure-of-eight suture or wire tension band. This converts the pull of the quadriceps into compression across the fracture: the same pull that would draw the fragments apart now presses them together.
Comminuted fractures are fixed with a combination of screws, plates, and cerclage wires (wires looped around the bone) through an incision down the front of the knee. The goal is a smooth, even joint surface on the back of the patella.
Recovery
The knee is protected in a brace locked in extension for walking during early recovery. Toe-touch or protected weight-bearing is used initially. Passive and active-assisted knee flexion begins early to prevent stiffness. Active extension against resistance is delayed until the fracture is healed. Full recovery is gradual, with milestones your surgeon will discuss at follow-up. Hardware irritation is common and removal is sometimes needed later.
Contact
For questions about this procedure or to schedule an evaluation, call the office at (830) 625-0009 or schedule an appointment online.
Physicians Who Perform Patella ORIF
Weight-Bearing After Repair
Controlled load is part of how bone heals. Once the fracture is stabilized with hardware, gentle weight through the limb stimulates the biology that builds callus (the new bone that bridges a fracture) and remodels bone. Completely offloading a fixed fracture for too long can actually slow healing and stiffen the joint above and below. Full body weight right away, however, can overload the construct before bone has caught up. The right answer sits in between: a partial weight-bearing progression decided by your surgeon based on your fracture pattern, the strength of the fixation, your bone quality, and how the repair looks on post-op imaging. We tell you exactly how much weight the limb can take, when to advance, and what to watch for.
Risks & Why We Still Recommend It
Every operation carries risk. This procedure is offered because the condition, when left untreated, can cause an extensor mechanism that cannot actively straighten the knee, which walking, stairs, and standing all depend on. The decision to proceed weighs the risks of surgery against the limitations the condition places on daily function. Surgery does not remove risk; it addresses a problem that is otherwise progressive. Whether it is appropriate is determined for each patient in consultation with the surgeon.
The risks we discuss with you before patella ORIF include:
- bleeding and infection
- anesthesia risk
- stiffness
- hardware irritation (kneeling is often symptomatic until the hardware is removed)
- non-union
- post-traumatic patellofemoral arthritis
- blood clot in the leg or lung
The indication to proceed is a displaced kneecap fracture with loss of active knee extension. If the operation is not right for you, we will say so.
Frequently Asked
questions we hear in clinicDoes every broken kneecap need surgery?
No. A patella that has cracked but has not separated, and where you can still lift the leg fully extended, may be manageable in a brace. Surgery is needed when the fragments separate and the system that straightens the knee stops working.
How can I tell the fracture is serious?
The clearest clinical sign is loss of active extension: if you cannot lift the leg with the knee held straight, the extensor mechanism is no longer working. That is the key clinical indication for surgery.
How is the kneecap put back together?
Simple two-piece fractures are typically fixed with two hollow screws and a figure-of-eight tension band, which converts the pull of the quadriceps into compression across the fracture. Shattered fractures are fixed with a combination of screws, plates, and wires looped around the bone, with the goal of a smooth, even joint surface on the back of the patella.
When can I bend my knee and walk on it?
The fixation is built to allow early knee bending within the first few days, since prolonged immobilization leads to stiffness. For walking, the knee is protected in a brace locked in extension early on, with toe-touch or protected weight-bearing at first; straightening the knee against resistance is delayed until the fracture is healed.
Will the hardware bother me later?
Hardware irritation is common, and kneeling is often symptomatic until the hardware is removed. Removal is sometimes needed later, once the fracture has healed.
Further Reading
External patient-education references and related OSI pages for additional background: