Medial Patellofemoral Ligament Reconstruction

Medial patellofemoral ligament reconstruction is a surgical treatment used to correct kneecap instability. This procedure is offered when the ligament on the inner side of the knee is torn and no longer able to keep the kneecap centered. When this ligament is damaged, the kneecap may slide out of place, causing pain, swelling, and repeated dislocations. The goal of surgery is to restore stability so the knee can bend and straighten smoothly without the kneecap slipping.

How Common It Is and Who Gets It? (Epidemiology)

This surgery is most often recommended for people who suffer repeated kneecap dislocations. It is common in young, active individuals and athletes, though it can affect people of any age. It may also be needed in people with naturally loose joints or alignment issues that make the kneecap more likely to slip.

Why It Happens – Causes (Etiology and Pathophysiology)

The medial patellofemoral ligament helps guide the kneecap as the knee bends. A strong impact, fall, or sudden twisting motion can tear this ligament. Some people are more prone to this injury due to loose joints, unusual bone alignment, or tight tissues on the outer side of the knee. When the ligament heals in a stretched or loose way, the kneecap becomes unstable and may dislocate repeatedly.

Direct Trauma: A significant blow or impact to the knee, such as a fall or collision during sports activities, can result in MPFL injury. This trauma may cause stretching or tearing of the ligament.

Repetitive Stress: Activities that involve repetitive bending, twisting, or sudden changes in direction can put excessive stress on the MPFL, leading to gradual wear and tear over time. This is particularly common in athletes who participate in sports like basketball, soccer, or volleyball.

Genetic Factors: Some individuals may have an inherent predisposition to ligament laxity or abnormalities in the alignment of the patella and femur, increasing their risk of MPFL injury.

Muscular Imbalance: Weakness or imbalance in the muscles surrounding the knee, especially the quadriceps and hamstrings, can disrupt the normal function of the MPFL and contribute to its injury.

Besides traumatic injuries or athletic injuries, some patients may be prone to kneecap dislocation owing to the increased laxity in their joints and ligaments, or due to tight structures (patellar retinaculum) on the outer side of the knee joint.

The torn ligament may heal naturally but usually heals in a slack manner causing instability of the kneecap. This may result in recurrent instability further aggravating the condition. Further, over time, the cartilage forming the patellofemoral joint may wear out leading to arthritis and degenerative changes.

How the Body Part Normally Works? (Relevant Anatomy)

The kneecap sits in a small groove at the front of the thigh bone. As the knee bends, the kneecap moves up and down this groove. The medial patellofemoral ligament, located on the inner side of the knee, acts like a strap to prevent the kneecap from drifting outward. When this ligament is torn, the kneecap can shift out of place.

MRI of the knee in axial section showing normal MPFL.

What You Might Feel – Symptoms (Clinical Presentation)

Medial Patellofemoral Ligament (MPFL) injury typically presents with several distinctive symptoms that can vary in intensity depending on the severity of the injury. The MPFL is a crucial ligament that stabilizes the patella (kneecap) and prevents it from dislocating towards the outer side of the knee. When this ligament is injured, it can lead to significant discomfort and functional limitations. Here are the common symptoms associated with MPFL injury:

Pain: Pain is usually the first symptom experienced with an MPFL injury. It can be localized to the inner side of the knee or around the patella. The pain may range from mild to severe and can be aggravated by activities that involve bending or straightening the knee, such as walking, running, or climbing stairs.

Swelling: Swelling around the patella or throughout the knee joint is another typical symptom of MPFL injury. The swelling may develop rapidly after the injury or gradually over time and can contribute to stiffness and limited range of motion in the knee.

Instability or Feeling of Giving Way: Since the MPFL plays a crucial role in stabilizing the patella, its injury can lead to a sense of instability in the knee. Patients may describe a feeling of the knee “giving way” or feeling as though it might dislocate, especially during activities that require sudden changes in direction or weight-bearing.

Difficulty Straightening the Knee: In some cases, individuals with an MPFL injury may experience difficulty fully straightening the affected knee. This limitation in extension, also known as knee flexion contracture, can further contribute to functional impairment and discomfort.

Audible Popping or Clicking Sensation: Injuries to the MPFL can sometimes be accompanied by audible popping or clicking sensations within the knee joint, particularly during movement. These sounds may occur due to the patella shifting out of its normal alignment or rubbing against other structures within the knee.

Tenderness to Touch: The area around the inner side of the knee, where the MPFL attaches to the femur and patella, may become tender to the touch. Palpating this area can elicit pain and discomfort, especially if the injury is acute or if there is associated inflammation.

How Doctors Find the Problem? (Diagnosis and Imaging)

Diagnosis begins with a review of how the injury occurred and any history of previous dislocations. A physical exam checks for looseness of the kneecap and signs of maltracking. X-rays help assess bone alignment. A computed tomography scan may be used to evaluate the shape of the knee. Magnetic resonance imaging shows the soft tissues clearly and can confirm a tear of the ligament.

Classification

Medial patellofemoral ligament injuries may be classified by the degree of tearing, the location of the tear, and the presence of repeated dislocations. Kneecap instability may also be graded by how often the kneecap slips and whether bone alignment contributes to the problem.

Other Problems That Can Feel Similar (Differential Diagnosis)

Other causes of knee pain or instability include meniscus tears, ligament sprains, cartilage injuries, bursitis, tendon irritation, and generalized joint looseness. A careful exam and imaging studies help separate these conditions from kneecap instability.

Treatment Options

Non-Surgical Care
Initial care may include rest, bracing, physical therapy, and activity changes. These treatments strengthen the knee muscles and improve control of the kneecap. Some people recover without surgery after a single dislocation.

Surgical Care
Surgery is recommended after two or more dislocations or when the kneecap remains unstable. The procedure uses a small tendon graft, often taken from one of the hamstring muscles, to rebuild the torn ligament. The surgeon works through very small incisions using a camera and special instruments. The graft is attached to the inner side of the kneecap and the inner lower part of the thigh bone. Sometimes, if bone alignment contributes to the problem, the surgeon may reposition the bump of bone where the kneecap tendon attaches. After surgery, the knee is placed in a brace to protect the repair.

Intraoperative image showing arthroscopic repair of MPFL.

Recovery and What to Expect After Treatment

Recovery includes rest, ice, elevation, and pain-relief medicine. Physical therapy begins soon after surgery to restore motion and strength. A brace is worn to keep the knee straight during early healing. Most people return to daily activities within a few months, although full recovery varies.

Benefits of MPFL Reconstruction

MPFL Reconstruction offers several benefits for individuals experiencing knee instability:

Improved Stability: By repairing the MPFL, the surgery helps restore stability to the knee joint, reducing the risk of patellar dislocations.

Pain Relief: For many people, MPFL Reconstruction can alleviate pain and discomfort associated with knee instability.

Enhanced Function: With a stable knee joint, you’ll likely experience improved function and mobility, allowing you to participate in activities without fear of injury.

Possible Risks or Side Effects (Complications)

Risks include infection, stiffness, and soreness. There is also a chance the graft may not heal properly and may require further treatment. Temporary loss of motion is possible but usually improves with therapy.

Long-Term Outlook (Prognosis)

Most people who undergo this surgery regain stability and improved comfort. They are often able to return to normal activities without the fear of repeated kneecap dislocation. Long-term outlook is generally good when proper rehabilitation is followed.

Out-of-Pocket Costs

Medicare

CPT Code 27427 – MPFL Reconstruction: $168.63
CPT Code 20922 – Autograft tendon harvest (if performed): $145.72
CPT Code 20924 – Allograft (if used): $119.99
CPT Code 29873 – Arthroscopic lateral release (if performed): $128.93

Medicare usually pays most of the approved charges for these services, but a patient share remains. Supplemental insurance plans such as Medigap, AARP, or Blue Cross Blue Shield typically take care of the remaining twenty percent that Medicare does not cover. These plans are meant to fill that gap, so when the procedure is Medicare-approved, patients often do not owe anything further.

If you have secondary insurance through an employer plan, TRICARE, or the Veterans Health Administration, it acts as the next payer after Medicare. After any deductible is met, the secondary plan may cover the rest of the balance, including coinsurance. These plans may have their own deductible, which often ranges from $100 to $300 depending on the specific policy.

Workers’ Compensation
If your MPFL reconstruction is necessary because of a work-related injury, Workers’ Compensation covers the entire surgery and related care. There are no out-of-pocket expenses for you.

No-Fault Insurance
If your knee injury is caused by a motor vehicle accident, No-Fault Insurance covers the full cost of the procedure. The only possible charge would be a small deductible depending on your policy.

Example
A patient named Sarah required MPFL reconstruction due to repeated kneecap dislocations. Her estimated Medicare responsibility was $168.63 plus related add-on procedure amounts. Because she also carried secondary insurance, it covered the remaining share, leaving her with no out-of-pocket costs.

Frequently Asked Questions (FAQ)

Q. Will I be able to walk after surgery?
A. Yes, you will usually walk with a brace and support soon after the procedure.

Q. When can I return to sports?
A. Most people return to sports in a few months, but this depends on healing and therapy progress.

Q. Will the surgery stop the kneecap from dislocating again?
A. The goal is to greatly reduce or eliminate instability, but results vary depending on the individual.

Q. Does the surgery leave large scars?
A. No, the incisions are very small.

Q. Is the procedure painful?
A. Some pain and swelling are expected, but these improve with medication, ice, and therapy.

Summary and Takeaway

Medial patellofemoral ligament reconstruction is used to correct kneecap instability caused by a torn ligament. It improves stability, reduces pain, and helps prevent repeated dislocations. The procedure uses a small tendon graft to rebuild the damaged ligament, followed by structured therapy to restore strength and movement. With proper care and recovery, most people return to normal daily activities with a stable knee.

Clinical Insight & Recent Findings

A recent study reviewed outcomes of medial patellofemoral ligament reconstruction in skeletally immature patients and found that anatomic techniques—such as surface-based and transosseous fixation—had significantly lower redislocation rates and higher return-to-sport rates compared with nonanatomic methods, without evidence of growth-plate disturbance .

These findings support the surgical principles described above, where restoring stability to the kneecap with a precise, anatomically placed graft is essential for preventing recurrent dislocations and improving long-term knee function

The study’s results align with the goal of MPFL reconstruction as outlined in the clinical overview: to rebuild the ligament using a tendon graft, correct maltracking when necessary, and help patients return to normal activity with improved stability and reduced pain. (‘Study of MPFL reconstruction outcomes – see PubMed.“)

Who Performs This Treatment? (Specialists and Team Involved)

This surgery is performed by orthopedic surgeons who specialize in knee injuries. Physician assistants, nurses, and physical therapists support the care before and after surgery.

When to See a Specialist?

You should see a specialist if your kneecap dislocates more than once, if the knee feels unstable, or if swelling and pain keep returning.

When to Go to the Emergency Room?

Go to the emergency room if the kneecap suddenly slips out of place and does not return on its own, if the knee becomes severely swollen, or if you are unable to move or straighten the leg.

What Recovery Really Looks Like?

Recovery involves controlled movement, gradual strengthening, and regular therapy. You may feel stiffness at first, but motion improves over time. Walking becomes easier as the ligament heals and the knee gains strength.

What Happens If You Ignore It?

If kneecap instability is ignored, repeated dislocations can lead to more pain, more damage to the cartilage, and the early development of arthritis.

How to Prevent It?

Strengthening the muscles around the knee, improving balance, and avoiding sudden twisting motions can help protect the kneecap. Proper rehabilitation after a first dislocation reduces future risk.

Nutrition and Bone or Joint Health

A balanced diet with protein, calcium, and vitamin D supports bone and tissue healing. Staying hydrated also helps joint function during recovery.

Activity and Lifestyle Modifications

After surgery, activities are reintroduced slowly. Low-impact exercises like cycling or swimming help rebuild strength without stressing the knee. High-impact sports should wait until full healing and clearance from your care team.