Aim: The aim of this study was to determine whether increasing obesity has an influence on the age at which joint replacements are undertaken at our centre.

Materials and Methods: The database was analyzed for age, oxford score and body mass index (BMI) at the time of surgery.

The patients were divided into 5 groups based on their BMI, BMI< 25(normal), 25–29.9(overweight), 30–34.9(obese), 35–39.9(moderately obese), 40 or more(morbidly obese).

BMI < 25 was treated as a control group for comparison.

Statistical analysis was done using t test.

Results: In total, 1369 patients were analyzed, 1025 with hip replacement and 344 with knee replacement The difference in mean oxford score at surgery was not statistically significant between the groups (p> .05). For those undergoing hip replacement, the mean age of morbidly obese was 10 years less as compared to those with BMI < 25. For those with knee replacement, the same difference was 13 years. The age at surgery fell as the BMI > 35 for both hip and knee replacement (p< . 05). This association was found to be stronger for patients with knee replacement than with hip replacement.

Conclusion: This study shows that there is a positive association between obesity and the age at which hip and replacements are required. Obese people with BMI > 35 are likely to require joint replacement at an earlier age as compared to people with BMI < 25. The age at which joint replacement in required falls as the BMI increases over 35. This association is strong for patients requiring total knee replacement, and moderate for patients with hip replacement.