A recent study reported that after six months of total joint replacement (TJR), severely/morbidly obese patients reported excellent pain relief and substantial functional gain. As obesity is associated with the risk of early complications, it cannot damper undergoing TJR to relieve symptoms.
Obesity is a disorder caused due to excess of body fat which makes it make prone to health problems. An obese person can experience lower function and more pain before and after total hip or knee replacement (THR or TKR). This study was carried out to investigate the changes in preoperative and postoperative function and pain in a large population to find out whether it is linked to obesity status.

A total of  2,040 patients in a representative U.S. Cohort, who had undergone the THR and 2,964 who had undergone the TKR from May 2011 to March 2013 were considered for this study. Their preoperative and 6-month postoperative data on joint pain (Hip disability and Osteoarthritis Outcome Score and Knee injury and Osteoarthritis Outcome Score), function (Short Form-36 Physical Component Summary [PCS] score), and body mass index (BMI) were gathered. The BMI status, defined as under or of normal weight, overweight, obese, severely obese, or morbidly obese was used to determine the preoperative and postoperative function and pain.

Out of the total patients undergoing THR, 59% were women, 94% were white, and 14% were severely or morbidly obese with an average age of 65 years. A substantial obesity level was concerned with a lower (worse) PCS score at baseline and 6 months postoperatively. The less postoperative functional gain was observed in severely and morbidly obese patients as compared to the other BMI groups.  The average postoperative pain scores did not vary appreciably according to BMI status as a greater obesity level was related with more pain at baseline but greater postoperative pain relief. Out of the total patients undergoing TKR, 61% were women, 93% were white, and 25% were severely or morbidly obese with an average age of 69 years. In these patients, a greater obesity level was concerned with a lower PCS score at baseline and 6 months. The postoperative gain in PCS score did not vary by BMI level. The average pain scores at 6 months were alike across the BMI levels as a greater obesity level was related to worse pain at baseline but greater pain relief at 6 months.