Obesity Impact on TJA Poorly Understood

Do individuals who have a total joint arthroplasty (TJA) lose weight following their surgery? With obesity being one of the major risk factors leading to the need for a hip or joint replacement, and joint pain severely restricting activity, the case that weight loss will occur postoperatively as mobility improves is both logical and intuitively compelling. But is this really what happens?

To find out, Maria Inacio, a doctoral candidate from the San Diego State University of California, San Diego, and her colleagues conducted a review of 12 studies in the current literature. They organized their results into a very interesting meta analysis and the surprising results are now available online in the journal Clinical Orthopaedics and Related Research.

Overall, Dr. Inacio and her colleagues found, between 14% and 49% of patients had lost weight a year after having a TJA. However, the ranges of weight loss are very high. To Inacio and her colleagues, this suggests and that patients are experiencing inconsistent weight loss and that the differences in study designs essentially mean that, so far, there is no conclusive pattern to whatever weight loss does occur.

Most amazingly, Inacio found that more patients gained weight than lost it after having a TJA.

Perhaps, said the study authors, investigations of obesity and TJA are of generally low quality and suffer from small sample sizes, poor methodology and a comparatively high risk of bias.

Commenting on the study, Stuart B. Goodman, M.D., Ph.D., of Stanford University, said in a September 10 news release: “Obese patients frequently tell clinicians that they are overweight because their painful hips or knees limit their physical activities and their capability to ‘burn calories.’ Unfortunately, after a comprehensive analysis of the data, the answer to this important question is still unknown.”

Inacio and her colleagues believe that since TJAs are such a common surgery and since the results of their retrospective study failed to tease out a discernible pattern that more research in this field is warranted and, more specifically, a large representative national study would be probably be required to answer these questions definitively.

Weight loss, either to prevent the development of osteoarthritis or to reduce long-term morbidity after a hip or knee replacement is a no-brainer worthy goal. To fully understand the relationship between TJA and weight loss or gain, clinicians will have to, for now, look beyond the current literature to obtain the most accurate picture of this very important patient population.