Referral for knee replacement surgery should be considered when patients have stabilised their weight after a weight-reduction program, optimised their medical health and have a reasonable risk profile for surgery. Morbidly obese patients have a higher prevalence of complications in all studies. The risk profile of a morbidly obese patient is dominated by their weight-related comorbidities and less influenced by age, and is more similar to that of a much older medically infirm patient than to a nonobese patient of their own age.
Once it has been decide that surgery should be performed, patients should be optimised in preparation for it. Paradoxically weight loss is associated with malnutrition and muscle atrophy, and maintenance of muscle tone with nonweight-bearing exercises such as swimming and nonimpact gym work is an important adjunct to weight loss interventions.
Osteoarthritis and knee pain are anticipated associations with morbid obesity. Disabling knee pain in a morbidly obese patient may be the focus of the patient’s attention but is merely the tip of the iceberg of a host of medical and psychological problems. Knee replacement surgery may be the conclusion of the therapeutic spectrum but has considerable risk and it would be remiss not to optimise the patient’s global comorbidities. A multidisciplinary program aimed at normalising body mass and maintaining muscle tone is likely to reduce knee pain and improve lifespan. Symptomatic knee osteoarthritis will inevitable progress and surgery is likely to be required and repeated several times over the patient’s lifespan. MT