The kneecap (patella) glides in a shallow groove at the end of the thigh bone as the knee bends and straightens. The medial patellofemoral ligament — the MPFL — is the main soft-tissue restraint that holds it on track, resisting the kneecap being pulled toward the outside of the knee.
At a glance: MPFL reconstruction rebuilds the torn medial patellofemoral ligament using a tendon graft, restoring the restraint that keeps the kneecap tracking in its groove. It is most often considered after recurrent kneecap dislocations, or after a first dislocation in a knee whose anatomy makes another one likely.
The MPFL runs from the inner border of the kneecap to a small, specific point on the inner side of the femur. It is not a large structure, and it is not what holds the kneecap in place through the full arc of motion — once the knee bends past about 30 degrees, the bony groove itself takes over. The MPFL does its work in the first part of that arc, when the kneecap is entering the groove and is least protected by bone.
That is why it tears the way it does. When the kneecap dislocates, it almost always dislocates laterally, toward the outside of the knee, and the MPFL is torn in the large majority of those events. Once torn, it does not reliably heal back to its original length and tension, and the kneecap loses its primary early-flexion restraint.
The knee and sports medicine surgeons at Midwest Orthopaedics at Rush evaluate and treat patellar instability across the full range — from a first dislocation managed without surgery to recurrent instability that needs ligament reconstruction, and revision surgery for patients whose earlier stabilization procedure did not hold.
A frank dislocation is usually unmistakable: the kneecap visibly shifts to the outside of the knee, there is immediate pain, and the knee often swells substantially within hours. Sometimes the kneecap relocates on its own as the knee straightens, which can leave patients unsure what actually happened.
Ongoing instability is subtler. Common symptoms include:
Diagnosis starts with history and examination: how the injury happened, how many times, and how the kneecap tracks and responds to pressure. Imaging then establishes both the ligament injury and the anatomy underneath it.
What the imaging shows matters as much as the number of dislocations. Two people with the same history can need different operations depending on the depth of the groove, the height of the kneecap, and the rotation of the limb.
A first-time dislocation in a knee with otherwise normal anatomy is often treated without surgery: a period of bracing, then physical therapy focused on quadriceps and hip strength and on how the leg is controlled during landing and cutting. Many people do well with that alone.
Surgery enters the conversation when:
If your kneecap has dislocated more than once, or a first dislocation has left the knee feeling unreliable, an evaluation will establish whether reconstruction is the right option for your knee.
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Rebuilding the ligament addresses the soft-tissue restraint. It does not change the bony architecture that may have caused the problem, which is why reconstruction is sometimes performed alongside another procedure:
Your surgeon will explain which combination applies to your knee and why. An MPFL reconstruction performed in isolation on a knee that needed a bony correction is one of the more common reasons a stabilization fails.
Some patients arrive having already had a stabilization procedure that did not hold. Recurrent instability after surgery is usually traceable to a specific cause: a graft fixed at the wrong point on the femur, a graft tensioned incorrectly, or an underlying bony problem that was never addressed. Revision starts by identifying which of those applies, because repeating the original operation without correcting the reason it failed tends to reproduce the failure. Revision reconstruction is technically more demanding than a first-time procedure and often involves addressing bony alignment at the same time.
These are different operations and the distinction matters. A repair stitches the existing torn ligament back together or reattaches it to bone. A reconstruction replaces it with a tendon graft.
Reconstruction is far more commonly performed for recurrent instability. A ligament that has already failed once, and that has often been stretched over multiple episodes, tends not to hold up when simply repaired. Repair is considered in a narrower set of circumstances, typically a first dislocation with a clean avulsion off bone in a patient without predisposing anatomy.
The procedure is usually done under regional or general anesthesia through small incisions, often with arthroscopic assistance to inspect the joint surfaces first, and is typically an outpatient operation. Four technical elements determine the result:
Recovery is individual, and what follows describes a typical uncomplicated course rather than a promise. Your surgeon sets your protocol, and it may differ — particularly if a bony procedure was performed at the same time, which generally slows every stage below.
Pain is most significant in the first several days and is managed with a combination of medication, ice, and elevation, then tapers. Patients are often surprised that the graft site can be as sore as the knee itself in the first week.
MPFL reconstruction carries the general risks of knee surgery, including infection, blood clots, stiffness, and persistent pain. Considerations more specific to this procedure include:
MPFL reconstruction is performed by board-certified, fellowship-trained orthopedic surgeons at Midwest Orthopaedics at Rush. Our knee and sports medicine surgeons completed subspecialty fellowship training after residency, and the group treats knee conditions across the full range — from first-time injuries through complex reconstruction.
Patellar instability is treated by our sports medicine and knee surgeons, several of whom care for competitive and professional athletes. Patients who have had a previous stabilization procedure that did not hold are evaluated for revision reconstruction.
Browse our knee specialists to read individual profiles, see where each surgeon practices, and request an appointment directly. Appointments are available across our Chicago-area locations.
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Most patients are walking without crutches within a few weeks and back to unrestricted daily activity within a few months. Return to cutting and pivoting sport takes longer and is decided by testing rather than by a date. A concurrent bony procedure extends every stage. Your surgeon will give you the protocol for your knee.
It is a real ligament reconstruction performed in an operating room under anesthesia, but it is usually done through small incisions as an outpatient procedure, and most patients go home the same day. It is generally considered less involved than a procedure that requires cutting and re-fixing bone.
Discomfort is most significant in the first several days and is managed with medication, ice, and elevation. Many patients find the graft harvest site as sore as the knee itself early on. Pain typically tapers substantially over the first two weeks.
Bracing protocols vary by surgeon and by whether a bony procedure was performed. A brace for the early weeks is common, often locked for walking at first and progressively unlocked as quadriceps control returns.
Walking with crutches usually begins right away, with many patients allowed to bear weight early. Driving generally resumes once you are off narcotic pain medication, out of a locked brace, and can control the pedals safely — longer for a right knee than a left. Both are individual, and a tibial tubercle osteotomy lengthens both timelines.
Often, yes. The graft is commonly secured with small implants — suture anchors or interference screws — which may be metal or a bioabsorbable material that dissolves over time. They stay in place and are not routinely removed. Your surgeon can tell you which fixation they use and why.
The graft is intended to be permanent. Most reconstructions continue to provide stability long-term, though further dislocation remains possible, particularly if underlying bony anatomy was not corrected. Published outcomes are generally favourable, and your surgeon can discuss what the evidence suggests for a knee like yours.
Cost depends on your insurance plan, deductible, the facility, whether other procedures are performed at the same time, and whether it is done as an outpatient. Our team can help you get an estimate specific to your coverage before surgery.
Often not. Many first-time dislocations are managed with bracing and physical therapy. Surgery is more likely to be recommended if a loose fragment needs addressing, or if your anatomy makes another dislocation likely. Imaging and examination guide that decision.
They are different operations with different recoveries. MPFL reconstruction is generally a smaller procedure with an earlier return to walking, while ACL reconstruction typically involves a longer and more structured return to sport. Comparing them directly is less useful than understanding what your own knee requires.
If your kneecap has dislocated or feels unstable, an evaluation is the first step in understanding why and what your options are. Schedule an appointment with the knee specialists at Midwest Orthopaedics at Rush.
This page is general information about a knee condition and its surgical treatment, and is not medical advice. Talk with a physician about your own symptoms, imaging, and treatment options.