Around 160,000 hip and knee replacements are performed each year in the UK. The split is roughly 50 / 50 but recent data suggests that knee replacement surgery is becoming more common. There has also been a trend for more joint replacements to be performed each year with one estimate projecting that the number will rise to 200,000 per year by 2035. Bearing in mind that the average cost to the NHS per case is currently around £7,000, it is clear that joint replacement surgery is an expensive business and that these costs are set to spiral as the population ages.
Hip joint replacement has been common in the UK since the 1960’s with knee replacements following a decade or so later. Indications for replacing hips and knees were and continue to be quite simple. The joint in question has to be chronically painful and poorly functioning. The most common cause of these issues is osteoarthritis (OA). This is a condition that primarily affects the joint surfaces. It often develops gradually and in the late stages of the condition can cause significant pain and severely limit function.
There are, however, some significant problems with the seemingly obvious link between joint surface damage to a hip or knee being in direct proportion to the degree of pain and disability that is experienced. Clinicians have for many years known that this seemingly obvious link, in reality doesn’t exist. It is common for some people to have severe OA changes to their joints (confirmed by X ray & MRI scanning) and have little or no pain. The opposite scenario is also frequently encountered. So the decision to replace a troublesome hip or knee joint, shouldn’t be made purely on the results of X rays or scans. This is because the degree of pain and disability that is attributed to either a hip or knee, is in most cases being caused by a number of issues. Issues that simply replacing sub standard joint surfaces won’t sort out. These include systemic inflammatory disorders, that should be dealt with by addressing diet, activity levels, lifestyle choices and social issues. Another factor is what’s termed “central sensitization” of the nervous system. This is where the volume switch in the nervous system is set too high, and as a consequence, disproportionate pain is experienced. If someone with a combination of these issues undergoes hip or knee replacement surgery, then the outcome may be bad. It has been estimated that 1 in 5 people who have knee replacements have ongoing pain, long after their surgery.
There is a growing amount of evidence that suggests that the best way forward is to be more selective in deciding who should benefit from joint replacement surgery. There is also good evidence that supports the non surgical approach to dealing with many cases of knee and hip pain that is attributed to OA. These include structured health education programmes, weight management, dietary advice and sensible exercise programmes. All of these have been shown to significantly reduce pain and to improve function.
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