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.

References

“Inferior outcomes of total knee replacement in early radiological stages of osteoarthritis”
Peck CN, Childs J, McLauchlan GJ, The Knee Vol 21, Issue 6, Dec 2014, 1229-1232

“Inverse Relationship Between Preoperative Radiographic Severity and Postoperative Pain in Patients with Osteoarthritis who Have Undergone Total Joint Arthroplasty”
Valdes AM, Doherty SA, Zhang W, Muir KR, Maciewicz RA, Doherty M Seminars in Arthritis and Rheumatism Vol 41, Issue 4, Feb 2012, 568-575

“The association of pre-operative body pain diagram scores with pain outcomes following total knee arthroplasty”
Dave AJ, Selzer F, LosinaI E, Usiskin I, Collins JE, Lee YC, Band P, Dalury DF, Iorio R, Kindsfater K, Katz JN Osteoarthritis and Cartilage Vol 25, Issue 5, May 2017, 667-675

“Does pre-surgical central modulation of pain influence outcome after total knee replacement? A systematic review”
Baert IAC, Lluch E, Mulder T, Nijs J, Noten S, Meeus M Osteoarthritis and Cartilage Vol 24, Issue 2, Feb 2016, 213-223

“The association between pre-operative pain sensitisation and chronic pain after knee replacement: an exploratory study”
Wylde V, Palmer S, Learmonth ID, Dieppe P, Osteoarthritis and Cartilage 21 (2013) 1253e1256

“Exploratory secondary analyses of a cognitive-behavioral intervention for knee osteoarthritis demonstrate reduction in biomarkers of adipocyte inflammation”
Huebner JL, , Landerman LR, Somers TJ, Keefe FJ, Guilak F, Blumenthal JA, Caldwell DS, Kraus VB, Osteoarthritis and Cartilage 24 (2016) 1528-1534

“Chronic Postoperative Pain After Primary and Revision Total Knee Arthroplasty” Petersen KK, Simonsen O, Laursen MB, Nielsen TA, Rasmussen S, Arendt-Nielsen L. Clin J Pain 2015;31:1-6

“What proportion of patients report long-term pain after total hip or knee replacement for osteoarthritis? A systematic review of prospective studies in unselected patients”. Beswick AD, Wylde V, Gooberman-Hill R, Blom A, Dieppe P. BMJ Open 2012;2:e000435-2011-000435. Print 2012

“Exercise for osteoarthritis of the knee: a Cochrane systematic review” Fransen M, McConnell S, Harmer AR, Van der Esch M, Simic M, Bennell KL Br J Sports Med 2015;49:1554-1557

“Comparable effects of exercise and analgesics for pain secondary to knee osteoarthritis: a meta-analysis of trials included in Cochrane systematic reviews” Henriksen M, Hansen JB, Klokker L, Bliddal H, Christensen R J of Comparative Effective Res vol. 5, NO. 4 systematic review
“Future projections of total hip and knee arthroplasty in the UK: results from the UK Clinical Practice Research Datalink” Culliford D, Maskell J, Judge A, .Cooper C, Prieto-Alhambra D, Osteoarthritis and Cartilage Vol 23, Issue 4, April 2015, 594-600

“Predicting the cost-effectiveness of total hip and knee replacement: a health economic analysis“
Jenkins PJ, Clement ND, Hamilton DF, Gaston P, Patton JT, Howie CR, Bone Joint J, 95-B (1) (2013), pp. 115-121

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