What is an MPFL reconstruction?
Normally, the patella (knee cap) sits in a groove (trochlear groove) on the end of 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 examine 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 incision 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.
What happens after my operation?
You will stay in hospital for one night to make sure that your pain is under control. You will be seen by a physiotherapist who will start your rehabilitation and will teach you to walk with crutches. You will have an x-ray of your knee to make sure that the devices used to fix the graft are in the right place. You will be discharged home soon after the x-ray has been taken. Your surgeon may not see you before you are discharged if there are no problems.
Pain Relief
During your procedure, your knee has been injected with Local Anaesthetic, when this wears off, you will feel more pain in the knee. The day after surgery may be more uncomfortable than the day of surgery. When taking pain medication, it is better to begin once the pain commences, rather than wait until it has built up. It is best to start with regular paracetamol (2 tablets, every 6 hours). You may have been prescribed something stronger such as Panadeine forte, Tramadol, or Endone. Endone and Tramadol can be taken in addition to paracetamol. Panadeine forte is used instead of panadol.
You may also have been prescribed anti-inflammatory medication. These should be taken with food. If you get indigestion or have ongoing nausea, the anti-inflammatory tablets should be stopped. It is usual to expect an increase in pain and swelling about four or five days after your procedure. Rest, ice, compression and elevation will help to reduce this.
Dressings
Small tapes hold the small puncture wounds together. Waterproof plastic patches cover them, so you can shower directly on to the knee. The dressings can be completely removed after 4 or 5 days. The cuts can be left open if healed and dry, or covered with a Band-Aid if still moist.
Swelling
Swelling is common after an arthroscopy. Fluid in the joint results in generalized swelling and is most obvious above the kneecap. Swelling is also common around the incisions and this can take some months to resolve.
Applying the R.I.C.E. principles – rest, ice, compression, and elevation, will help swelling.
REST: During the first 3 days you should rest with your leg elevated as much as possible. You can then generally increase your activity, guided by your pain and swelling.
ICE: For the first week you should try to ice your knee 3 times a day for 20 minutes. After this time ice the knee following exercise and at the end of the day until your swelling reduces.
COMPRESSION: You will usually have a Tubi grip stocking around your knee. Sometimes you will have a bandage. The bandage can be replaced by a compression stocking on the day after surgery. The compression stoking should be worn during the day until your swelling reduces (usually about 2-4 weeks)
ELEVATION: Elevating the leg will assist in reducing swelling.
Crutches
Unless otherwise instructed you can place as much weight on the leg as comfortable with the help of crutches for the first 2 to 3 days following surgery.
To start with, the pattern of walking is ‘crutches, bad leg, good leg’. Once you are more comfortable, the crutches and operated leg go forward together. You may find it easier to use just one crutch. Use it with the opposite arm i.e. for a left knee operation; use the crutch with your right arm.
To manage steps with crutches, use the following guide:
- UP good leg, bad leg, crutches
- DOWN – crutches, bad leg, good leg
Post-operative appointment
You will have a postoperative appointment with your surgeon approximately two weeks after your procedure.
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.