Patella Stabilisation Surgery

Patella stabilisation surgery is a term used to describe a procedure to stabilise the kneecap (patella).  The procedure is used in the treatment of conditions such as patella dislocation and patella subluxation.

Persistent patella dislocation is an uncommon, disabling condition commonly treated by surgery to stabilise the kneecap.  In most cases, soft tissue surgery is suitable to recreate the injured ligament.  This ligament is called the medial patellofemoral ligament and attaches the inside of the thighbone to the inside of the kneecap.  It can be easily reconstructed using hamstring tendon taken from your knee.

In some cases, medial patellofemoral ligament reconstruction may be unsuitable.  If this is the case, a bony operation is carried out.  During this procedure, the bony lump on the front of your shin which attaches the kneecap tendon is moved a centimetre towards the inside of your leg.

What is the Patella?

The patella (also known as the kneecap) is a small, triangular bone that rests in the centre of the knee between the femur (thighbone) and tibia (shinbone) and helps extend the knee and protect the joint from impact.  A tendon at the top of the patella and a ligament at the bottom secure the bone in place.  As the knee bends, the patella slides along a groove in the femur.

Occasionally the kneecap pops out of its groove and becomes dislocated; an injury also known as patellar subluxation.  Dislocation occurs, the kneecap can no longer slide along the groove and this can aggravate and damage cartilage on both the femur and the tibia.  If you injure your patella, you may experience difficulty when walking, running, standing or exercising.  Patella dislocation and injury is common with people that take part in extreme physical activity.  Injuries tend to appear more often in high impact sports such as football, rugby or wrestling.

What is Patella Subluxation?

In a fully functioning knee, when carrying out movements, the patella slides up and down within a groove at the bottom of the thigh bone.  Instability is caused when the muscles holding the patella in its position are weakened. Instability can cause the patella to be pulled out of the groove and towards the outer side of the knee. Weakening of the muscles that hold the patella in its correct position causes instability of the kneecap.  Instability can cause the patella to be pulled out of the femoral groove and towards the outer side of the knee known as patella subluxation.  Patella subluxation causes discomfort and irritation at the front of the knee when moving.

What is Patella Dislocation?

A dislocation of the patella occurs when the kneecap completely pops out of its groove and sits on the outside of the knee joint.  Frequently, following a first time dislocation, ligaments that were securing the kneecap in position are torn.  The most common ligament that is torn because of a knee dislocation is the medial patellofemoral ligament (MPFL).  Knee dislocation and tearing of the MPFL causes the patella to leave its correct position and therefore fails to slide up and down properly (maltracking).  Maltracking of the patella causes a significant amount of pain and irritation at the front of the knee when carrying out movements.

Causes of an Unstable Patella

The kneecap (patella) joins the muscles in the front of the thigh to the shinbone (tibia).  As you bend or straighten your leg, your kneecap is pulled up or down.  The thighbone (femur) has a groove at one end to allow the kneecap to move.

There are two main types of patella instability.  The first is caused by an injury to the ligaments surrounding your kneecap that is generally caused by a sporting injury where the knee has received a blow to the side, causing it to move out of its groove, either completely or partially (subluxation).  This can result in ligament damage.
The second sort of instability is caused by a structural issue that results in you having excessive movement of your kneecap in its groove.  You may have a shallower groove in your femur, or your kneecap may be smaller than usual or situated higher up in front of your knee.

Patella subluxations and dislocations generally affect young and active people, particularly between the ages of 10 to 20 years.  If you live with hypermobility syndrome or have weaker thigh muscles, you may also experience patella instability.

Symptoms

It is important to spot symptoms as soon as you can to enable you time to strengthen your muscles and stabilise your kneecap.  Unfortunately, the more your kneecap dislocates, the slacker and stretched the supporting ligaments become, increasing your risk of repeated dislocations.

If you have an unstable patella, you may suffer from the following symptoms:

• Buckling sensation in the knee
• You feel like you cannot support your weight
• Unable to straighten your knee
• A sensation that your knee catches when bending or straightening your leg
• Pain in the front of the knee that increases with activity
• Knee pain whilst sitting
• Stiffness
• Creaking or cracking noises during movement
• Swelling

The symptoms range from minor looseness, where the kneecap moves marginally out of the groove triggering a distinctive clunking sensation (patellar maltracking), to complete dislocation of your kneecap.  Dislocation can be temporary, where the patella repositions itself or it may dislocate and stay out until it is manipulated back into position.

How is Patella Subluxation Diagnosed?

Before proceeding with any treatment, your consultant will need to assess the cause of your patella instability.  They may order an X-ray or MRI scan.  If this is the first time you have experienced a dislocation, your consultant may recommend physiotherapy to strengthen the muscles around your knee joint or a brace to help hold the joint in place.

Your doctor will start by carrying out a physical examination, bending and straightening the affected knee and feeling the area around the kneecap.  They may also take measurements to assess whether the bones are out of position or if the thigh muscles are weakened.

X-rays

Most commonly associated with joint or bone problems, an X-ray is a painless diagnostic tool that checks for fractures and signs of wear and tear or injury.  Your doctor may order and X-ray to understand how the kneecap fits into the groove at the bottom of the patella and eliminate other possible reasons for the pain, such as bone injuries.

Magnetic Resonance Imaging (MRI) Scans

An MRI scan uses a strong magnetic field and radio waves to create a detailed picture of the tissue and organs inside of your body such as ligaments, cartilage and tendons surrounding the patella.

Non-Surgical Patella Stabilisation Treatment

If it is your first time experiencing a subluxation or dislocation, or your kneecap is only partially dislocated, non-surgical treatment is likely to be recommended for you. Treatments includes:

• Physical therapy
• RICE (rest, icing, compression, and elevation)
• Nonsteroidal anti-inflammatory drugs (NSAID), such as ibuprofen
• Crutches to take the weight off the affected knee
• Immobilisation (a brace or a cast)
• Specialised footwear to reduce pressure on the kneecap

You can continue to train in a pool and do physical therapy to increase mobility while the joint remains immobile.  The aim is to return to your normal activities within 1 – 3 months.

Patella Stabilisation Surgery

If conservative treatments such as physical therapy, immobilisation and medication fail to stabilise the patella, your doctor may recommend patella stabilisation surgery.  Surgery is used to readjust and tighten tendons to keep the kneecap on track, or to release tissues that pull the kneecap off track.  The surgical options include both open and arthroscopic techniques.

If the kneecap has been totally dislocated out of its groove, the first step is to return the kneecap to its correct position.  This process is called reduction.  In some cases, reduction occurs spontaneously.  Other times, your doctor will have to use gentle force to get the kneecap back in place.  A dislocation can damage the underside of the kneecap and the end of the thighbone, which can result in additional pain and arthritis.  Arthroscopic patella stabilisation surgery can correct this condition.

Patella stabilisation surgery is typically carried out under general anaesthetic.  The method of surgery performed will depend on your individual circumstances.  In most cases, patella stabilisation surgery can be performed arthroscopically (minimally invasive keyhole surgery).  The amount of time you spend in hospital will depend on what procedure is performed. Be sure to discuss which technique will be used with your doctor.  Surgical techniques that are used include:

Medial Patella-Femoral Ligament (MPFL) Reconstruction

The MPFL is the link between the end of the thighbone (femur) and the inner side of the kneecap (patella).  When the kneecap dislocates, the MPFL is always torn. This procedure can be carried out using a combination of keyhole surgery and minimally invasive open surgery.  Following repeat dislocations, in order to repair the MPFL, a new ligament must be made.  This can be done using a tendon or ligament from another part of your body.  The new MPFL ligament is formed, reshaped and attached to the thighbone and kneecap, holding the kneecap in the correct position.

In most cases, you will have to stay in hospital for one night.  You should be able to support your own weight (with crutches), in 1 – 2 weeks following surgery.  You can expect to get back to your usual activities approximately 3 months’ post-surgery.

Lateral Release Surgery

Lateral release surgery may be recommended to correct the position of the patella and to stabilise the knee if the patella has moved from its groove and towards the outer side of the knee joint.  This is an arthroscopic procedure that involves only a small incision around 2 inches.  It is performed by releasing the tight lateral tissue and muscles around the knee, allowing the knee to sit in the socket better and make it more stable.

Medial Imbrication/Reefing

A medial imbrication is an arthroscopic (keyhole) procedure using stitches to tighten the tissue on the inner side of the knee.  Just as lateral release surgery loosens the structures, pulling the kneecap to the outside, a medial imbrication tightens the structures on the inner side of the knee.  Lateral release and medial reefing can be carried out at the same time.

Bone Realignment Procedure

If your kneecap instability is caused by having an abnormal anatomy, such as a kneecap that is in a higher position than usual (patella alta), you may be offered bone realignment surgery.  The operation involves detaching the kneecap tendon, together with a small lump of bone to which it is attached, and moving it.  It is then secured in its new position with screws.

In most cases, you are able to go home the next day, with the knee immobilised in a brace.  After approximately 2 weeks, you should be able to bear your own weight, supported by the brace; after 6 weeks, most people can support themselves without a brace.

Post-Operative Recovery

You will need to arrange for someone to drive you home following patella stabilisation surgery as you will be unable to drive until you can confidently perform an emergency stop (4 – 6 weeks) and have full and painless range of motion in your knee.

Depending on your procedure, you may go home with a set of crutches to use as you may not be allowed to put full weight on your affected side for several weeks.  You may be prescribed pain relief medication, and it is important that you follow the dosage instructions.  If you experience discomfort or pain, icing and elevating your leg will help control swelling and stiffness.

To help regain your strength and mobility, your doctor will likely prescribe physiotherapy.  The quickest recovery process is by following a lateral release procedure with the longest recovery following bone realignment surgery.  You will be asked to wear a long, hinged brace for around 6 weeks following surgery.  Elbow crutches may be required when you begin to bear weight on the affected knee; this will help maintain mobility before progressing to full weight bearing.

Dislocations of the patella can occur following patella stabilisation surgery, although they are uncommon.  In the majority of cases, you can resume your pre-injury level of activity without the risk of dislocating your kneecap.

Physiotherapy following patella stabilisation surgery is vital to guarantee the success of the surgery and to guarantee the return of full or partial function in your knee. Depending on the speed of your recovery and the nature of surgery you had, rehabilitation could take from 3 months to a year.

Risks and Complications

Most people make a full recovery following patella stabilisation surgery.  However, as with any invasive surgical procedure, there is the possibility of complications. These can include:

• Infection
• Nerve damage
• Bleeding or blood clots
• A reaction to the anaesthetic

Specific complications relating to patella stabilisation surgery may include:

• Continued stiffness
• Recurring dislocation

You can use your private medical insurance or pay for your Patella Stabilisation Surgery treatment. We offer competitive, fixed price packages. If you are using your health insurance, please contact your insurer first for approval and let them know you’d like to be treated at either the One Ashford Hospital or One Hatfield Hospital.

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• Modern purpose-built hospital opened in March 2016 (Ashford) December 2017 (Hatfield)
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• Little or no waiting time
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