Weight gain is often reported by patients who succumb to impaired activity as a result of progressive osteoarthritis of the hip or knee. Optimistic views of weight loss after joint replacement are often held by patients. We studied the affect of lower limb arthroplasty on body weight.

We reviewed 144 patients having undergone hip and knee arthroplasty and were functionally well. Infected cases were excluded. Average age was 65 years and average follow up was 27 months. The Body Mass Index (BMI) was prospectively measured at follow up and compared to immediate pre-operative BMI.

Our findings demonstrated an average rise in BMI post-operatively which was statistically significant. A rise in post operative BMI was seen in patients who were obese to start with or those who had undergone a total hip replacement (statistically significant). Moderate rises were seen in patients who had underwent hip resurfacing procedures or those who were overweight preoperatively (p=0.06).

These findings are useful in informing patients of achievable expectations following joint replacement surgery and preoperative overweightness should be treated as a separate entity unrelated to co-existing joint degeneration.