This operation is done to reposition where the kneecap sits in the groove on the front of the thigh bone (the femoral trochlea). Most commonly this is done for kneecap instability and dislocations , but it can also be an option to offload damaged cartilage (arthritis) on one section of the kneecap. This operation is sometimes undertaken in combination with reconstruction of the medial patellofemoral ligament (MPFL).
Tubercle osteotomy is normally carried out under a general anesthetic with additional local anesthetic used at the end of the procedure. The operation starts with a careful keyhole examination of the knee joint (arthroscopy) to directly visualize the tracking of the kneecap as the knee bends, and to check for (and treat if possible) any cartilage damage that may have occurred. The re-positioning is done by carefully lifting and then reattaching the bottom end of the kneecap tendon where it attaches to the shinbone (where there is a bump known as the tibial tuberosity) through a surgical cut approximately 6cm long. The new position is then checked again via the keyhole camera before the fixation is completed (either with simple bone screws or a small plate and screws). The surgical cuts are then sutured, covered with a dressing and a compression bandage. A brace is then applied to the knee to control range of movement.
Factors to Consider
What are the risks of surgery?
Complications are rare following MPFL reconstruction but can occur.
- Infection – the risks of infection are low based on only small incisions being used and the surgery being relatively short, however a superficial infection can occur that can be treated successfully with oral antibiotics. Very rarely a deeper infection in the joint may require a further operation.
- Deep Vein Thrombosis (DVT) – is rare following this type of surgery but does sometimes occur (>1%). During surgery precautions are taken to minimise the risk by using pumps on your calves and you are encouraged to move shortly after surgery has been completed. If you have an increased risk of developing a DVT your surgeon may opt to treat you with medication to thin the blood for a short time after your surgery to reduce the risk.
- Nerve damage – as part of the surgery small nerves within the skin are cut which can result in permanent loss of sensation in a patch of skin around the scars.
- Stiffness – the surgery is designed to stabilize your kneecap, with the aim being to make it feel the same as your un-injured side. Rarely patients develop more scar tissue (arthrofibrosis) which can result in a greater level of stiffness than desired. This is a higher risk if surgery is undertaken too soon after any injury.
- Prominent metalwork – the fixation screws below the knee can sometimes feel prominent and uncomfortable. If this happens then a small operation can be done to remove these once the bone has healed – usually any time from 6 months onwards.
After Surgery
Rehabilitation
The aim of surgery is to improve the kneecap tracking, allowing you to return to normal function, including sports where appropriate. The early post-operative recovery is focussed on pain control, slowly regaining movement, and then restoring the strength of the quadriceps muscles on the front of the thigh.
You will need to wear a knee brace for any walking / loading activity for the first 6 weeks, initially locked in extension (out straight) to prevent excess loading of the healing bone, and you will use the brace settings to control your bending range as it gradually increases week by week.
Your recovery will need to be guided by an experienced physiotherapist and will be tailored to your individual needs and will progress at the rate that matches your healing and progress.