The Potential Value of Dual-Energy X-Ray Absorptiometry in Orthopedics

CASE STUDY: WEIGHT CHANGE IN A RECREATIONAL ATHLETE

It is not uncommon to encounter patients who have substantial weight changes as a result of lifestyle changes, such as dieting. It is also possible that body weight remains stable, but variable changes occur in the amount and distribution of fat and lean mass. Combining exercise with dieting is more likely to be associated with preservation or gain of lean mass. Such a case is presented. After a knee injury, a club tennis player reported gaining 30 lb in the subsequent 12 months. She enrolled in a DXA study, and serial body composition assessments were performed as she started a diet program and exercised on a treadmill and stationary bike. Table 3 shows body composition changes from baseline.

Table 3. Body Composition Changes After Dieting and Exercise

Dual-energy X-ray absorptiometry scans were performed using a GE Lunar Prodigy system.

Although gross weight using a scale clearly showed progress in losing weight, it did not provide information about redistribution of fat and lean mass. The DXA body composition assessment showed that at follow up, there was a 22% decrease in total grams of fat and a 6% increase in lean mass (changes were uniform over different body regions). Her BMI still categorized her as being overweight; however, her body composition changes demonstrated that diet and exercise were producing positive results.

CONCLUSION

There are many ways in which DXA technology could provide orthopedists with valuable baseline and postoperative and post-treatment information about their patients. This technology could be used more effectively by orthopedists in both general clinical practice and research.