Knee revision surgery

What is knee revision surgery?

Knee replacements have been carried out in the UK since the 1970s, with approximately 80,000 performed every year in England and Wales. This includes both total and partial knee arthroplasty (joint replacement) where either the whole knee or one side of the knee is removed and fitted with a prosthesis (artificial joint part). These operations are for people who have problems such as severe arthritis, injury or deformity in the knee joint, which cause pain and greatly impact mobility and quality of life.

On the whole, these are successful procedures, and many patients have good outcomes. However, the new joint parts do not last forever, and this is where knee revision surgery comes in. If the new joint fails, a second surgery is required to ‘revise’ the joint: taking out any old or dysfunctional prostheses, clearing any debris or inflamed tissues (known as debridement) and creating a new joint replacement. Without further complications, most successfully-replaced knee joints can be expected to last around 20 years before needing to be replaced again, however, this is greatly dependent on the age and activity level of its recipient. Overall, long-term follow-up of patients receiving knee replacements showed that only 3.9% required revision of the joint within 10 years, rising to 10.3% requiring revision by 20 years. However, in younger individuals (around 50 years old), the rate rose to 35% needing a second surgery. Overall revision rates for the UK are below 5%.

The challenge with revision surgery is that, because the joint has already been operated on, the procedure is generally very difficult to carry out, is associated with a higher rate of complications, and is often not quite as good as the original replacement. As such, knee revision surgery is a highly skilled procedure, requiring both expert opinion and experienced hands to complete successfully.

Why would knee revision surgery be needed?

In addition to general wear and tear and age of the new joint, there are several other complications (normal risks of having any joint replacement), which, although occur rarely, are important indications for the need of revision surgery. These are described below. Usually, when a knee joint requires revision it is due to a number of contributing factors leading to the failure of the implant.

Loosening of implant

When an artificial joint part is put into place, it is secured by one of two methods. The first is using cemented parts, where a specially designed medical cement is used to fix the joint part in place. The second method uses joint parts that are particularly designed to allow the bone to grow into them, securing them in place. Both methods are shown to be effective, however, in some individuals, there is still loosening of one or more of the new joint parts which can result in both pain and reduced joint function.

This is more likely to occur with increasing age and use of the implant, however, factors such as very high-impact activity or being overweight can accelerate this process and increase the likelihood of it happening. Sometimes, a phenomenon known as ‘osteolysis’ may also occur. This is where the bone itself around the implant begins to degenerate, resulting in loosening. The National Joint Registry shows that in 2017, half of the knee revisions in the UK were as a result of ‘aseptic loosening’ of the joint implants (loosening of the implant without infection).

 Infection

Whilst infection is a complication to consider in any invasive medical procedure, there are several types of infection that are particularly troublesome in the context of joint prostheses. Following the initial risk of infection from the stay in the hospital and the surgery itself, joint implants can become infected over the coming years. This results in pain, redness, swelling and sometimes even dislodging of the joint implants themselves, causing the new joint to fail.

In particular cases, a joint ‘wash out’ and exchange of the spacer part of the implant between the thigh and shin bone can be performed, without the need for removal and replacement of the fixed parts of the joint; this can be sufficient to treat the infection. However, in many cases, a ‘staged revision’ is required. This involves removal of all the joint implant parts and debridement (surgical removal) of infected tissues, followed by a rest period and course of strong antibiotics, before having a second operation to put in a new joint once the infection is clear.

Instability

The knee joint has six main ‘soft tissue’ elements that stabilise the joint. Two of these, the menisci (pads of cartilage which sit on top of the shin bone, cushioning the thigh bone on top), are removed as part of the joint replacement. The remaining four elements are ligaments (collateral and cruciate ligaments) that run between the thigh and shin bones providing support and stability to the joint. In order to get access to that joint space during replacement surgery, these ligaments can often become slightly damaged. This is usually managed well with appropriate physiotherapy and rehabilitation after the surgery, but in a few cases the ligaments are either too damaged or do not heal. This results in an unstable joint that may ‘give way’, swell and cause pain. Knee revision surgery can restore this stability and balance to the knee to maximise function.

Stiffness

Joint stiffness is a major issue following knee joint replacement and is initially targeted with graded physiotherapy. However, it remains that some patients experience severe stiffness in the affected joint, resulting in major restrictions in the range of movement, which can be severely disabling. Following the failure of physiotherapy to alleviate stiffening of the joint, manipulation under general anaesthetic can be effective. This involves going to sleep under a general anaesthetic so you won’t feel anything, then the surgeon will move the knee around freely, breaking down any of the scar tissue that has built up around the joint. This is often a successful procedure and, whilst still carries the risks associated with anaesthetic, solves the problem without the need for another surgical intervention. Following this, surgical revision of the joint has also been shown to increase the range of movement and improve outcomes overall. Although this also carries the increased risks associated with revision knee surgery, data suggests that, as only 5% of knee revisions are carried out as a result of ongoing joint stiffness, physiotherapy and manipulation under anaesthetic are effective strategies to manage this.

Fracture

Often when adults get older, bones can weaken as part of the natural ageing process or from ‘osteoporosis’ (where bones become more brittle). Additionally, when a prosthetic joint implant is fitted into a bone, that part of the bone can become weaker than normal, meaning that the bone is more prone to breaks or fractures around the implant. Unfortunately, if the bone surrounding the implant becomes fractured, this means that there is nothing anchoring the implant and it will become unstable. This presents a scenario that is more complicated than a simple bone fracture, as the replaced joint must also be taken into account. In these cases, a larger operation to both stabilise and fix the fracture, as well as replace the artificial joint parts, is carried out to provide optimal long-term outcomes for the joint.

What to do to prepare for knee revision surgery

Steps to prepare for knee revision surgery are fairly similar to those for initial knee replacement surgery. The main difference is that, if you are undergoing a revision procedure, it is likely that this is because of problems with the current artificial joint, which is probably causing pain. Moving around on a painful joint is hard at the best of times, but keeping mobile and building up the muscle around the joint after the operation is not only essential but will also enhance recovery.

Here are seven quick tips to consider when preparing for knee revision surgery:

1. Arm yourself with knowledge: You have already had a similar operation, make sure you get to know what is happening this time round and why
2. Ask questions: your consultant is there to look after you as well as make sure you understand what is happening and answer any questions you might have
3. Know the risks: Revision knee surgery has a higher risk profile than a simple joint replacement. Your consultant is the best person to talk to about these risks, and you should be fully informed of these before any procedure goes ahead
4. Find out about alternatives: Depending on your individual situation, there may be some alternative management, such as focused physiotherapy, which may provide relief without the need for another operation
5. Stay well: Essential for any procedure, complications are much less likely to occur if you are in good health beforehand, so take some extra time to look after yourself and stay as well as possible
6. Exercise: Easier said than done, but any exercise that you can do will confer some benefit both before and after the operation. A good mix of exercise that gets your heart rate up and strengthens your muscles is ideal, but anything you are able to do will be well worth it; keeping moving is key
7. A healthy BMI: Another tricky one if you are struggling to exercise with a painful knee, but having a healthy BMI can help to reduce the risk of complications of both the anaesthetic and the new joint and will also help with rehabilitation. A healthy BMI (body mass index) is between 18.5 and 25 and is calculated from your height and weight. Ask your GP for more information or take a look at the NHS guide to BMI

What are the risks of knee revision surgery?

As mentioned previously, knee revision surgery confers a higher level of risk and complication to initial knee replacements, as the joint has already been operated on. This means that revision surgery is longer and more complex, however, as with the original operation, every precaution to minimise risk will be taken, and your consultant will use their medical judgement and experience to weigh up the risks versus benefits of the procedure to advise you.

Risks of revision knee surgery include:

• Poor wound healing
• Continued stiffness and limited range of motion in the knee
• Infection of both the surgical wound and/or the joint implants
• Bleeding
• Fracture of the bone during the fitting of the joint implants
• Damage to nerves or blood vessels around the knee
• Dislocation; a very rare complication, but generally thought to be more likely in a revised joint replacement
• Pulmonary embolism; a blood clot in the lungs

Advice from our experts

Here is some advice from one of our top consultant orthopaedic surgeons, Mr Matthew Hearth, who has a special interest in hip and knee replacements, including revision surgery:

‘My name is Matthew Hearth and I am a Consultant Orthopaedic Surgeon. My specialist interest is Lower Limb Joint reconstruction. As such one of the operations I perform is revision total knee replacement.

•  Revision total knee replacement is unfortunately a bigger surgical procedure than a primary or first knee replacement. It does therefore take longer to recover. Whereas a patient is often much better following a primary knee replacement at 2 to 3 months following surgery, a good rule of thumb would be to double this time period after revision knee surgery.
• There are a number of reasons why a revision knee replacement may be performed. The most common reason is that the primary knee replacement eventually wears out and becomes loose (aseptic loosening). This typically happens at greater than 10 years after the first knee replacement is inserted but may be much longer than that ( >15years). This will cause the patient to have pain, reduced mobility and a general loss of function. If this happens, a revision knee replacement may be needed. Other less common causes of knee replacement failure include

1. Infection of the knee replacement
2. Instability, ie the ligaments in the knee become poorly functional and the knee gives way causing falls.
3. Malalignment of the knee; sometimes this causes pain necessitating revision of the knee replacement.

• Revision total knee replacement involves removing the previous total knee replacement and replacing it with a new knee replacement. As there has been previous surgery this is a bigger procedure, patients should therefore expect a longer recovery time.
• The inpatient stay is usually from 3 to 5 nights in hospital. This is followed by outpatient monitoring by the consultant and the physiotherapy department.
• The results of revision knee replacement have improved over recent years to be almost on a par with primary total knee replacement. A patient could expect 10 year survival of the revision knee replacement approximately 85% of the time.
• Tips for recovery would include

1. Follow the advice of the surgeon/physiotherapist
2. Take appropriate pain-killers, usually for at least the first 2 weeks post-operatively. Revision knee replacement can be painful and the painkillers will help the patient be able to do the rehabilitation.
3. Make sure the rehabilitation exercises are performed, this is probably the most important
4. Do not be disheartened if initially, things go slowly, it is big surgery and things take longer to get better!’