MPFL Reconstruction

What is an MPFL reconstruction?

Normally, the patella (knee cap) sits in a groove (trochlear groove) on the end of the the femur (thigh bone). The medial patellofemoral ligament (MPFL) is a ligament that attaches to the inner side of the patella and inner side of the end of the femur. It behaves like a rope that prevents the patella from dislocating toward the outer side of the knee. After a patella has dislocated once, the MPFL is often ruptured or stretched and so is less able to prevent the patella dislocating in future. If the patella keeps dislocating or feels unstable, the MPFL can be reconstructed to stabilise the patella.

Who is an MPFL reconstruction performed on?

MPFL reconstructions are performed on people who have had one or more patella dislocations and have ongoing instability of the patella. It is suitable for people with a normal, shallow or flat trochlear groove. If the groove is severely deformed and is domed, an MPFL reconstruction is usually not appropriate and a trochleoplasty is performed instead.

How is an MPFL reconstruction performed?

MPFL reconstructions are usually performed under a general anaesthetic (fully asleep). A 3cm oblique incision is made over the front of the knee and through this, one of the hamstring tendons is taken from the back of the thigh.This graft is then doubled over a metal button to form the new ligament. An arthroscopy is then performed to emaine the knee joint and the way that the patella moves. A 2cm incision is made over the inner side of the patella and a small tunnel is drilled through the patella. The graft is inserted through the patella and prevented from coming back by the metal button which sits over tunnel on the other side. Another 2cm inicision is made over the inner side of the end of the femur and another tunnel is drilled across the width of the femur. The graft is brought down along the path of the old ligament and then inserted into the femur tunnel. It is then fixed in place with a metal screw. Usually, the screw and button are not removed. The wounds are then sutured closed.

How long will I be in hospital?

Usually, you will spend night in hospital. The knee can be quite painful after the operation and the pain is best managed in hospital.

What is the recovery time after an MPFL reconstruction?

You will be able to walk fully on the operated leg straight away, although crutches are often required for a week or two for support. Bending and straightening of the knee are encouraged immediately after surgery. It is common to experience pain on the inner side of the knee along the graft for a few months after the operation.

You will need to take 3-4 weeks off work after an MPFL reconstruction.

Physiotherapy commences immediately after the operation, working on regaining range of movement and muscle strength. There is a rehabilitation program that your surgeon will give you that gradually increases your level of activity under the guidance of your physiotherapist. It takes about nine months before it is safe to return to sport.

What is the expected outcome of an MPFL reconstruction?

The vast majority (over 90%) of people who undergo an MPFL reconstruction for patella instability are happy with the result. It is a very reliable procedure for stabilising the patella. In terms of pain, though, the results can be a bit unpredictable. Often, the knee is more comfortable than it was before the operation but the pain may persist and sometimes a non-painful knee can be made painful.

What risks are associated with an MPFL reconstruction?

As with any operation, there is a small risk associated with a general anaesthetic, a risk of infection, numbness or sensitivity around the scars and a risk of deep vein thrombosis.

We don't know yet whether the chance of developing arthritis in the knee is lower after an MPFL reconstruction. Hopefully, by improving the way the patella travels in the trochlear groove, the chance of developing arthritis is less.