Associations of surgical and nonsurgical weight loss with knee musculature: a cohort study of obese adults

BACKGROUND: Marked weight loss reduces lean body mass and quadriceps thickness. It is unclear whether muscle loss varies according to the method of weight loss.

OBJECTIVE: This study compared the association of surgical versus nonsurgical weight loss with change in vastus medialis (VM) properties in obese adults.

METHODS: Twenty obese patients (body mass index≥30 kg/m²) who lost weight via laparoscopic gastric banding were matched for weight loss with obese patients who lost weight nonsurgically. The thickness and fat infiltration of VM were assessed at baseline and a mean of 2.4 years later.

RESULTS: After adjusting for confounders, the annual change in VM thickness was -2.9% in the surgical group and -.5% for the nonsurgical group (P = .02). There was also a tendency toward an increased risk for VM fat infiltration to be reduced when weight loss occurred nonsurgically (OR 5.1, 95% CI .8-32.8; P = .09).

CONCLUSIONS: Compared with nonsurgical weight loss, laparoscopic gastric banding was associated with greater VM muscle thickness loss. Relative to laparoscopic gastric banding, there was also a tendency toward an increased risk for VM fat infiltration to be reduced with nonsurgical weight loss. Close attention to preserving muscle properties at the knee when significant amounts of weight loss have occurred is required. Physical therapy may be important in the management of patients after laparoscopic gastric banding in an attempt to preserve skeletal muscle mass.