Joint Replacement May Not Lead to Weight Loss

Janis C. Kelly

September 20, 2012

September 20, 2012 — Studies assessing the effect of total hip arthroplasty (THA) and/or total knee arthroplasty (TKA) on postsurgical weight loss are inadequate and inconclusive, according to a systematic review published online September 7 in Clinical Orthopedics and Related Research.

Maria C.S. Inacio, a doctoral candidate from San Diego State University/University of California, and colleagues conclude that the (admittedly low-quality) studies they analyzed provide "no conclusive evidence that weight or body composition increases, decreases, or remains the same after [total joint arthroplasty (TJA)]."

Weight loss might be expected to occur as a byproduct of THA or of TKA because of postsurgical reduction in pain and increased mobility, but Inacio, who is employed at Kaiser Permanente, and colleagues asked whether such weight loss actually happens.

Obesity itself is a major risk factor leading to the need for a hip or knee replacement, and weight loss after TJA might reduce the risk for complications such as prosthetic loosening, thus reducing the likelihood of further surgery.

The authors found 12 studies that met inclusion criteria, including a single case-cohort study and 11 case series. Most were from single-surgeon or single-hospital series.

"Owing to the observational nature of the studies and the serious limitations identified, all were considered very low quality according to [Grading of Recommendations, Assessment, Development, and Evaluation] criteria," the authors write.

Some degree of weight loss at least 1 year after TJA was reported in 14% to 49% of patients, but in many cases this did not meet the US Food and Drug Administration definition for clinically meaningful weight loss (at least 5% of body weight). The ranges of weight loss suggested inconsistent loss, and the differences in the study designs meant that overall there was no conclusive pattern. Furthermore, more patients gained weight (21% - 75%) than lost weight (14% - 49%).

In a CORR Insights commentary on the manuscript, Stuart B. Goodman, MD, PhD, of Stanford University in California, said, "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," according to a news release.

The authors have disclosed no relevant financial relationships.

Clin Orthoped Rel Res. Published online September 7, 2012. Full text