Medial Patello-Femoral Ligament (MPFL) Reconstruction

This page is intended to help you understand the operation and the recovery following the surgical procedure to stabilise your kneecap (patella)

It is not intended to be a comprehensive guide, and you should discuss any further queries that you may have with your consultant surgeon.   

 What is the medial patellofemoral ligament?

The knee cap (patella) is designed to help the muscles on the front of your thigh to straighten your leg.  As you bend and straighten your leg, the patella glides in a groove at the end of your thigh bone (femur) known as the trochlear groove of the femur.  Sometimes this groove may not be very deep and this can contribute to instability of the patella and a feeling that it may slide out of the groove (dislocate) when the knee moves.  Stability of the patella can also be affected by the alignment of your leg so that patients who are knock-kneed (valgus alignment) have a higher chance of developing patella instability.  This instability may also be caused by an injury that dislocates the patella. 

To aid stability of the patella there are a number of soft-tissues that attach to it.  These structures can weaken over time particularly if there is little stability provided by a flat trochlear groove.  This may lead to recurrent partial dislocations (subluxations) or complete dislocations.  This is painful and causes scuffing (wear) to the under-surface of the patella and may lead to the development of osteoarthritis.  

Of the soft tissue structures that stabilise the knee, the medial patellofemoral ligament (MPFL) is the most important.  It is a thin strip of tough tissue that attaches from the inside edge of your patella to the inner side of the lower end of your femur, to anchor and prevent the patella from sliding out of its groove. 

If your patella feels unstable or is regularly dislocating this can often be improved by strengthening the muscles around the knee using physiotherapy.  If this does not provide much improvement then surgical reconstruction of the MPFL may improve the situation.     

Surgical reconstruction of the MPFL

Surgical reconstruction of the MPFL is carried out under a general anaesthetic. It is a minimally invasive procedure and will require only a few small incisions on the front and side of your knee.  A small camera will be used to look inside your knee and to repair any other damage that may be found in the joint.

One of your hamstring tendons will be used, harvested through one of the small incisions that have been made.  The new ligament is secured by passing it through a small tunnel made on the inner edge of the patella and then fixing it to a short tunnel in the inner side of the femur.  Great care is taken not to under or over tighten the ligament so that it can effectively carry out its new job. 

Intended benefits of the surgery:

The aim of the procedure is to prevent the feeling of instability (giving way) and the recurrent dislocations that occur when the MPFL is disrupted.  This is usually an extremely successful operation with high levels of satisfaction for those who undergo this surgery.

Some of the identified risks with this type of surgery:

Some risks associated with this procedure are:

  • The operation may not to work patients may develop recurrent instability, The risk of this is 5-10%.
  • There will be some bleeding + swelling after the procedure but it is extremely rare for this to cause a serious problem.
  • There is a very small risk of a blood clot forming in the legs (deep venous thrombosis) which may require treatment with medicines to thin the blood (less than 1 in 200 cases). Even more rarely, one of these clots may travel to the lungs (pulmonary embolism) which may be serious.
  • Post-operative infection is very rare but could cause further damage to your knee. Very occasionally further surgery to wash the knee out is required.
  • Patients are often left with an area of numbness over the inner aspect of their knee. This isn’t often troublesome and usually reduces with time.  It can occasionally be permanent.
  • Fixing the MPFL and preventing further instability of the patella does not necessarily protect you from developing osteoarthritis in the future. This is due mainly to any damage that has already been done.
  • A small proportion of patients are left with persistent pain at the front of their knee after any knee operation.
  • Failure of the wound to heal is extremely rare. Certain individuals are at a higher risk of this (e.g. those with diabetes or peripheral vascular disease).  If you are at risk, this will be discussed with you prior to the operation. 

N.B. Many of the above complications apply to all forms of knee surgery

What are the alternatives to an MPFL reconstruction?

The main alternative is to do nothing at all and to continue with the physiotherapy and exercises that you are already doing.  If no improvement has been noticed it is unlikely that any further improvement is going to occur.  You may be happy just to accept the problem and not go through with any surgery.

If it is found that you have a shallow trochlear groove in which the patella glides, an operation that may help you is a Trochleoplasty.  This bigger operation involves lifting the articular surface of the groove and then hollowing out the groove to make it deeper.  The articular surface is then replaced and patella stability is improved as the groove is deeper.  This procedure is only required if your trochlear groove is completely absent.  

Follow up procedure and hospital stay

The majority of people undergoing MPFL reconstruction will have to spend just one night in hospital.  Rarely, a person may need to be kept in hospital if a complication has occurred.

You should be able to resume driving in 4 weeks and it is expected that you can return to sporting activities from 4-6 months. 

Follow-up appointments should be arranged for 4-6 weeks post op and then at 3 months and 6 months

If you have any further queries or concerns after your operation then please contact Nicki on 01926 772731

If you experience any excessive pain, swelling, or discharge then please contact either the hospital or your own GP immediately.

Post-operative rehabilitation

Day of operation / Day 1

  • Return from surgery with a wool / crepe dressing. This dressing will be changed to a Tubigrip before you leave hospital the next day.
  • You will be encouraged to practice full active extension of your operated leg.
  • Your physiotherapist will show you static quadriceps exercises, proceeding on to straight leg raises (you may need to help lift your leg with a towel/belt so that your knee is kept straight when lifting your leg).
  • You will be encouraged to mobilise so that you are full weight bearing – in full extension with crutches (you may have a brace only if you have poor quadriceps control).

Week 1


  • Diminish swelling / inflammation.
  • Regain active quadriceps / VMO control.
  • Maintain full knee extension / hyperextension.
  • At least 45° knee flexion.
  • Patient education regarding rehabilitation process

Week 2: Wound check and Suture (stitch) removal by nurse

Weeks 2 – 4


  • Control swelling / inflammation.
  • Gradual increase in range of movement (within limits of pain).
  • At least 90° knee flexion by end of week 2.
  • At least 120° knee flexion by end of week 4.
  • Quadriceps strengthening (especially VMO).

Week 4: begin to drive short distances if able to perform an emergency stop safely.

Week 4: Return to sedentary job.

Weeks 5 – 6


  • Full flexion.
  • Good activation of quadriceps and straight leg raise with no lag (knee bend).
  • Can start swimming ( not breaststroke until 10-12 weeks post operatively).
  • Can return to work in a physical job if able to carry out light duties with limited walking.

Week 6: Clinic review Ensure appropriate progress.

Weeks 7 – 12


  • Increase quadriceps and VMO control for restoration of proper patella tracking.
  • Improve muscular strength / control / endurance without exacerbation of symptoms.
  • No altered walking pattern.
  • Functional exercise.
  • Begin kneeling.
  • Able to return to gym (with guidance from physiotherapist).
  • Can start breaststroke when swimming.

Week 12 clinic review: check of progress.

Weeks 12 – 16

  • Goals
  • Knee extension strength at least 70% other knee.
  • Work towards achieving maximum strength and endurance of leg musculature.
  • Functional activity drills.
  • Good active patella control with no evidence of lateral tracking or instability.

Weeks 16+


  • Full pain free range of movement.
  • Continued improvement in quadriceps strength (80% or greater of contra lateral leg).
  • Improve functional strength and balance reactions.
  • Maximise confidence in returning to appropriate activity level.
  • Functional return to work / sport. ** Return to sports dictated by particular sport, ability, fitness and confidence – minimum 4 months (with guidance from physiotherapist and surgeon)