Reviewed by Dr Vishal Pai
An MPFL reconstruction replaces the torn ligament that holds your kneecap (patella) in place, to stop the kneecap from dislocating again. This page explains how the operation is done, what recovery involves, and the results and risks you can expect.
At a Glance
- The medial patellofemoral ligament (MPFL) is the main ligament stopping your kneecap from sliding out to the side. It usually tears when the kneecap dislocates.
- An MPFL reconstruction is a well-established operation for a kneecap that keeps dislocating. It is also used when a dislocation has knocked off a piece of cartilage or bone.
- The new ligament is usually made from one of your hamstring tendons, and most people go home the morning after surgery.
- After an MPFL reconstruction alone, you can usually put weight on your leg straight away and you won’t need a brace.
- Another dislocation after surgery is uncommon, and most people return to sport, usually from about 6 months once they pass return-to-play testing.
What is an MPFL reconstruction?
Your kneecap sits in a groove at the end of your thigh bone (the trochlea). On the inner side of the knee, the medial patellofemoral ligament (MPFL) acts like a check rein that stops the kneecap from sliding outwards. When the kneecap dislocates, this ligament is usually torn or stretched [1], and it often doesn’t heal tightly enough to hold the kneecap in place.
An MPFL reconstruction replaces that ligament with a graft, usually one of your own hamstring tendons, and restores the restraint on the inner side of the kneecap. It doesn’t change the shape of the groove or where the kneecap tendon attaches to the shin. If either of those is part of the problem, another operation may be added (see when another operation is added).
Who might need an MPFL reconstruction?
An MPFL reconstruction is a common operation for a kneecap that has dislocated more than once, or that keeps feeling as if it’s about to slip out. [2] It is also used when a dislocation has knocked off a piece of cartilage or bone that needs to be fixed or removed, because the ligament can be reconstructed during the same operation.
After a first dislocation, physiotherapy to strengthen the thigh and hip muscles is one option and surgery is another. The patella stabilisation surgery page compares the two.
Further dislocations are more likely if you are younger or still growing, if the groove for your kneecap is shallow (trochlear dysplasia), if your kneecap sits higher than usual (patella alta), or if the kneecap tendon attaches further to the outside than usual. [3] Dr Vishal Pai looks for each of these on your scans, because they help decide whether an MPFL reconstruction on its own is enough. You can read more about these causes on the kneecap instability page.
What is involved in MPFL reconstruction surgery?
The operation is done under a general anaesthetic, and most people stay one night in hospital. The main steps are:
1. Knee arthroscopy
Two to three small (less than 1 cm) cuts let a camera and instruments into the knee. Dr Vishal Pai checks the cartilage for damage and treats any loose fragments.
2. Graft harvest
One hamstring tendon, usually the gracilis, is taken through a small cut below the inner side of the knee and prepared as the new ligament.
3. Attaching the graft to the kneecap
One end of the graft is fixed to the inner edge of the kneecap with small anchors that hold it with stitches. This onlay technique means no tunnel is drilled through the kneecap.
4. Thigh bone tunnel and fixation
A small tunnel is drilled in the thigh bone where the natural ligament attaches, and its position is checked with live X-ray imaging during the operation. The graft is then tensioned so the kneecap sits centrally in its groove, and held in the tunnel with a screw.
When is an MPFL reconstruction combined with another operation?
An MPFL reconstruction rebuilds the ligament but leaves the bones as they are. If the shape or alignment of your knee is a large part of the problem, Dr Vishal Pai may add a second procedure during the same operation. The procedures aren’t interchangeable, because each one corrects a different problem. [4]
- A tibial tubercle osteotomy (TTO, also called a tibial tuberosity osteotomy) moves the bony bump on the shin where the kneecap tendon attaches. It is used when the tendon attaches too far to the outside, or when the kneecap sits very high.
- A trochleoplasty deepens the groove at the end of the thigh bone. It is occasionally needed when the groove is severely flat.
Adding a TTO makes recovery slower, as described below. The patella stabilisation surgery page compares the three operations and explains how the choice is made.
How long does it take to recover from an MPFL reconstruction?
Recovery is measured in months. Your physiotherapist leads your rehabilitation and moves you on when your knee is ready, rather than on a fixed date, so progress varies from person to person.
As a rough guide, after an MPFL reconstruction on its own:
- Day after surgeryHome after an X-ray. You can usually put weight on your leg straight away, with no brace
- 2 weeksWound check with Dr Vishal Pai. You can shower without a dressing once the wound has healed
- 2–4 weeksMost people with a desk job return to work
- 6 weeksDriving, once you’re walking without crutches and off strong pain medication. Physically demanding work may take up to 6 weeks
- 8 weeksDr Vishal Pai expects your knee to straighten fully and bend past 90 degrees
- 6 monthsDr Vishal Pai reviews you to check you’re ready to return to sport. You can go back once you’ve passed return-to-play testing
If a tibial tubercle osteotomy is done at the same time, recovery is slower. You’ll use crutches for about 6 weeks and a straight-knee brace when walking for the first 2 weeks, and an X-ray at 8 weeks checks that the bone is healing. Return to sport is at 6 months at the earliest, and often takes longer than after an MPFL reconstruction alone.
Swelling can last 3–6 months, and bruising usually fades over 2–3 weeks. Ice the knee for at least 20 minutes, 4 times a day, and avoid resting with a pillow under your knee, because it makes the knee harder to straighten.
Dr Vishal Pai usually reviews you at about 6 months to check that your kneecap is stable, your knee moves fully and you’re ready to return to sport. Most people go back from about 6 months, once their physiotherapist’s return-to-play testing shows their strength and control are ready. Some people take a little longer, which is normal. [5]
What results can you expect?
Most people get back to sport after an MPFL reconstruction, [5] [2] and most of them return at the same level as before or higher. [2] When people didn’t return, or went back at a lower level, the most common reason was fear of injuring the knee again. [6] Children and teenagers have similar results. [7]
How likely is another dislocation?
Another dislocation after an MPFL reconstruction is uncommon. In large reviews, about 1 to 3 in 100 people had their kneecap dislocate or become unstable again. [8] [9] Surgery also lowers the chance of the kneecap dislocating again compared with physiotherapy alone. [10] The risk is higher if the shape or alignment of your knee isn’t corrected, which is why your scans are reviewed carefully before surgery.
What are the risks and complications?
Every operation carries risks, and Dr Vishal Pai goes through them with you before you decide. Most people have no complications. [2] The risks specific to an MPFL reconstruction are:
- Ongoing pain at the front of the knee, the most commonly reported problem, which can relate to cartilage damage from earlier dislocations, the position of the graft, or the shape of the groove [11]
- Stiffness. If the knee isn’t bending or straightening well by 6–8 weeks, a short anaesthetic to gently bend the knee and break up scar tissue may be needed [11]
- The kneecap becoming unstable again (see the figures above), which may need further surgery
- A break in the kneecap, which is uncommon and usually needs an operation to fix [12]
The general risks of any knee operation, including infection, bleeding into the knee and blood clots in the leg (deep vein thrombosis, or DVT), are uncommon. They are listed on the patella stabilisation surgery page, and you will receive a written information sheet with the full list of risks before surgery.
Dislocating your kneecap raises the chance of arthritis behind the kneecap later in life, especially if dislocations keep happening or the cartilage was damaged, [13] so preventing further dislocations is one of the aims of surgery.
Where does Dr Vishal Pai consult and operate?
Dr Vishal Pai consults at Sandringham Orthopaedic Specialists, Suite 1, 60 Bay Road, Sandringham. He operates at Calvary Holmesglen Private Hospital, 490 South Road, Moorabbin, and The Avenue Hospital, 40 The Avenue, Windsor. Patients come from across Bayside, Glen Eira and the Mornington Peninsula, and some travel from regional Victoria. For consultation fees, see appointments and fees.
References
Show all 14 referencesHide references
- Migliorini F et al. 2022. High rates of damage to the medial patellofemoral ligament, lateral trochlea and patellar crest after acute patellar dislocation: MRI analysis. Arthroscopy.
- Platt BN et al. 2021. Return to sport after medial patellofemoral ligament reconstruction: a systematic review and meta-analysis. The American Journal of Sports Medicine.
- Huntington LS et al. 2019. Factors associated with an increased risk of recurrence after a first-time patellar dislocation: a systematic review and meta-analysis. The American Journal of Sports Medicine.
- Phillips AR et al. 2024. Isolated medial patellofemoral ligament reconstruction results in lower failure and complication rates than isolated trochleoplasty and tibial tubercle osteotomy: a systematic review. Arthroscopy.
- Manjunath AK et al. 2020. Return to play after medial patellofemoral ligament reconstruction: a systematic review. The American Journal of Sports Medicine.
- Ryan PC et al. 2024. Fear of re-injury, psychological factors, and sport played have negative impact on return to sport following medial patellofemoral ligament reconstruction for patellar instability. Arthroscopy.
- Migliorini F et al. 2022. Outcomes, return to sport, and failures of MPFL reconstruction using autografts in children and adolescents with recurrent patellofemoral instability: a systematic review. Children.
- Schneider DK et al. 2016. Outcomes after isolated medial patellofemoral ligament reconstruction for the treatment of recurrent lateral patellar dislocations: a systematic review and meta-analysis. The American Journal of Sports Medicine.
- Vivekanantha P et al. 2022. Isolated medial patellofemoral ligament reconstruction results in similar postoperative outcomes as medial patellofemoral ligament reconstruction and tibial-tubercle osteotomy: a systematic review and meta-analysis. Knee Surgery, Sports Traumatology, Arthroscopy.
- Cohen D et al. 2022. MPFL reconstruction results in lower redislocation rates and higher functional outcomes than rehabilitation: a systematic review and meta-analysis. Knee Surgery, Sports Traumatology, Arthroscopy.
- Jackson GR et al. 2023. Complication rates after medial patellofemoral ligament reconstruction range from 0% to 32% with 0–11% recurrent instability: a systematic review. Arthroscopy.
- Abelleyra Lastoria DA et al. 2026. The incidence and epidemiology of patellar fractures following medial patellofemoral ligament reconstruction: a systematic review and meta-analysis. Archives of Orthopaedic and Trauma Surgery.
- Sanders TL et al. 2017. Patellofemoral arthritis after lateral patellar dislocation: a matched population-based analysis. The American Journal of Sports Medicine.
- Morgan VK et al. 2025. Medial patellofemoral ligament reconstruction in skeletally immature patients: a systematic review of outcomes by fixation technique. Orthopaedic Journal of Sports Medicine.
Frequently asked questions
Can a torn MPFL heal without surgery?
A torn MPFL often heals in a stretched position, so it may not hold the kneecap as firmly as before. In studies of people treated with rehabilitation after a first dislocation, about 3 in 10 dislocated again. [10] If your kneecap keeps dislocating, an MPFL reconstruction replaces the ligament. Both options are compared on the patella stabilisation surgery page.
Is an MPFL reconstruction a major operation?
It’s done through a few small cuts under a general anaesthetic, and most people go home the morning after surgery. Recovery still takes several months of rehabilitation, and it takes longer if a bone procedure is added at the same time.
What scars will I have after an MPFL reconstruction?
You’ll have two or three small cuts (less than 1 cm) at the front of the knee for the camera, a small cut below the inner side of the knee where the hamstring tendon is taken, and small cuts over the inner edge of the kneecap and the inner side of the thigh bone, where the graft is fixed.
What graft is used to rebuild the ligament?
Dr Vishal Pai usually uses one of your own hamstring tendons, most often the gracilis, taken through a small cut below the inner side of the knee. The area where it was taken can feel tender or numb for a while.
Will an MPFL reconstruction affect my teenager's growth plates?
Kneecap dislocations often happen while the growth plates around the knee are still open. Bone procedures such as a tibial tubercle osteotomy or a trochleoplasty can damage a growth plate, so they’re usually delayed until growth has finished. For children who are still growing, an MPFL reconstruction can be done with the tunnel in the thigh bone placed to avoid the growth plate. Studies of this approach in children haven’t reported growth problems, [14] and Dr Vishal Pai will talk it through with you and your family.
When can I swim after an MPFL reconstruction?
Keep the wound dry until your 2-week check. Avoid swimming and pool-based rehabilitation for at least 3 weeks, and until the wound has fully healed, because getting it wet too early can raise the risk of infection.
Next step
Talk through your options
If your kneecap has dislocated more than once, Dr Vishal Pai can examine your knee, review your scans and explain whether an MPFL reconstruction is right for you.