Obesity and Knee and Hip Replacement Surgery

It is estimated that one in ten people in the United Kingdom will require a knee replacement with this number increasing as the population ages.

Body Mass Index (BMI) is calculated by a person’s weight in kilograms divided by their height in metres squared. A BMI between 25 and 30 is classified as overweight, 30 to 35 as obese (class 1), 35 – 40 obese (class 2), and over 40 is morbidly obese.

Some health authorities and hospitals restrict the availability of hip and knee replacements to patients above a certain BMI. This has been justified by the increase in some complications.

An article in the British Medical Journal, investigated the incidence of repeat surgery, death and knee pain and function following knee replacement, in obese patients.

There was a slight increased risk of revision surgery in obese class 1 and class 2 patients, compared to those with a normal BMI, but was felt to be within acceptable limits.

Deaths within 90 days of surgery were rare and highest in the underweight group.

All people had improved knee function and pain with no difference between the weight groups.

The study only followed patients to six months, and if patients were investigated for a longer period of time, differences may be shown.

Other important complications such as infection, were not investigated.

It is important that patients manage their arthritis as well as they are able. The NICE arthritis advice (found under the patient information leaflets on my website) outline all of these measures.

If you come to surgery, it is important that you optimise your health in relation to weight, nutrition, diabetic control, medical conditions and fitness.