The majority of patients who have a total knee replacement to treat conditions like osteoarthritis go on to make a good recovery and can get back to doing the things they love. But sadly, for some people, chronic pain can persist even after a knee replacement.
What is neuropathic pain?
In the immediate post-surgical period, it is normal to experience a certain amount of pain and swelling as the knee starts to heal. Your surgical team will offer advice about how to manage this discomfort, which normally involves taking painkillers and doing exercises recommended by a physiotherapist.
However, if you are still experiencing pain three to six months after surgery, you may have neuropathic pain, which is the result of nerve damage or entrapped nerves in or around the knee joint. It is important to talk to your orthopaedic surgeon if you are experiencing ongoing pain after a knee replacement, as they will want to ensure that it is not due to a problem with the prosthetic implant itself, such as an infection or loosening, or an allergic reaction to the metal it is made from. Once issues such as these have been ruled out, your surgeon may conclude that you have postsurgical neuropathic knee pain and will discuss the options with you.
How is neuropathic pain caused?
While orthopaedic surgeons take great care to minimise the risk of nerve damage during surgery, unfortunately, it is impossible to eliminate it altogether. Prior to the procedure, your surgical team will explain the possible risks, however small they may be, so you can make an informed choice. There are a number of reasons why nerve damage might occur. During the surgery, incisions may cut through nerves lying close to the skin, as well as those that run alongside the muscles, tendons, ligaments and blood vessels around the knee joint. Surgical instruments are used to hold tissues out of the way while the surgeon operates on your knee joint and this can sometimes result in compression injuries or stretching. The implant itself may injure nearby nerves, or you may develop post-surgical complications such as an infection or inflammation which can lead to nerve damage.
How common is neuropathic pain after a total knee replacement?
A team from the University of Bristol recently conducted a study, that was published in The Bone and Joint Journal. The aim was to determine the prevalence and patterns of neuropathic pain in patients reporting chronic pain three months after a total knee replacement. The study followed patients for a year after their surgery.
The researchers studied a group of 363 patients who had reported pain scoring 14 and over according to the Oxford Knee Score pain scale, between 2016 and 2019. The patients had all undergone a total knee replacement at one of eight NHS hospitals across the UK. The patients’ self-reported neuropathic pain and postoperative pain levels were assessed at three, nine and 15 months after surgery using painDETECT and Douleur Neuropathique 4 questionnaires, collected via the post.
Among patients reporting chronic pain three months after having a total knee replacement, symptoms of neuropathic pain were common. Half of the patients who were experiencing neuropathic pain at three months continued to experience symptoms over the next 12 months. A quarter of them had improved while for a tenth of these patients, their neuropathic symptoms fluctuated over time. A subgroup of participants reported new, late-onset neuropathic symptoms. Overall, the average neuropathic pain scores improved between three and 15 months after a total knee replacement.
The researchers concluded that, although neuropathic symptoms improved over time, up to half of those affected continued to report painful neuropathic symptoms 15 months after their total knee replacements. They recommended that postoperative care should include screening, assessment and treatment of neuropathic pain in patients whose postoperative pain does not resolve as expected.
If you are concerned about neuropathic pain after a total knee replacement or would like to discuss the possible risks of nerve damage during surgery, please contact us.
Professor Joseph Queally offers both conventional knee replacement surgery and Mako robotic-arm assisted knee replacements, which have been shown to improve outcomes and reduce the risk of complications.
