The pros and cons of patella realignment surgery for knee instability

Recurrent instability in the knee joint, whether caused by an injury or an alignment issue, can cause discomfort and pain and interrupt an active lifestyle. In this detailed account of the available treatment options, highly experienced consultant trauma and orthopaedic surgeon Mr David Christopher Rees expertly outlines the pros and cons of both surgical procedures and non-surgical methods of realigning and strengthening the knee cap’s position.

What causes instability in the knee joint?

The kneecap, also known as the patella, usually sits in a groove (trochlea) which is found at the tip of the thighbone (femur). This groove allows the patella to move up and down as the knee bends and straightens. This movement is called patellar tracking and if the kneecap sits correctly on the centre of the femur, it can occur as normal.

If the position of the kneecap is deviated, however, this can cause troublesome symptoms including discomfort and instability in the joint. This can occur if the patella is subject to excessive outward or lateral force which cause the movement to become abnormal, which is known as patellar malalignment.

In serious cases, the kneecap can even become dislocated from its usual position and can pop outside of the knee joint. This usually occurs following a serious injury but if the ligaments which surround the kneecap are damaged, chronic instability issues can occur.

Are there non-surgical treatment options for patellar instability?

With targeted physiotherapy, the muscles of thigh, particularly the quadriceps, can be specifically trained and made stronger in order to better stabilise the kneecap. In some cases, a knee brace may also help to lessen anterior knee pain.

When conservative (non-surgical) treatments are unsuccessful, surgery may be required to realign the patella and put an end to pain and instability in the joint. Although patellar realignment surgery doesn’t guarantee an improvement in symptoms for every patient, in many cases it is very effective.

How can surgery be used to treat patellar instability?

There are several different surgical methods used to treat patellar instability. A keyhole procedure known as arthroscopic lateral release is the most simple, during which the surgeon cuts some of the tight lateral structures which allows the kneecap to have a more central position. In some cases, this type of surgery is insufficient and may need to be accompanied by a reinforcement or double breasting, also known as reefing, of the damaged medial structures, including some of the quadriceps muscles. This is referred to as VMO advancement.

Additionally, there are other types of surgery in which the patella is pulled to a central position by releasing the lateral part of the patellar tendon so it is able to be reattached to the tibia. This is often reinforced by performing lateral release and medial reefing procedures. In some cases, the bony attachment of the patellar tendon must also be centred to allow the kneecap to sit more centrally in the trochlea groove and fixed with screws. After this procedure, patients wear a knee brace for between two and three months to aid recovery. Unfortunately, this surgical method can leave some patients with pain in the top of the shin area and even an overcorrection of the initial instability, meaning that other surgical techniques are now seen as more preferable.

An alternative procedure, involving the reconstruction of the medial patellofemoral ligament, also known as MPFL, is becoming more popular. When the kneecap is fully dislocated, this often ruptures the MPFL or leaves it stretched and seriously weakened, which can be assessed using an MRI scan. Much like an ACL reconstruction, which is performed to repair one of the knee’s key ligaments, a length of hamstring tendon can be taken from the lower thigh and used to bind the kneecap to the inside of the thighbone. This makes the kneecap less likely to be pulled laterally.

Is knee surgery risky?

Surgery does not offer a full guarantee of improved knee stability but it can be very effective. There are many options available, including physiotherapy, which should be thoroughly discussed with your surgeon to determine which is the best treatment for your individual case. Much like any surgical procedure, knee surgery of this type has a small risk of complications such as infection, blood clotting or neurovascular damage.

If you are seeking treatment for knee instability and wish to book a consultation with Mr Rees to discuss your options, don’t hesitate to visit his Top Doctors profile where you can do so.