Biometric Changes Up to 2 Years After Hip Arthroscopy in National Collegiate Athletic Association Division I Athletes

Patients who undergo hip arthroscopy for femoroacetabular impingement (FAI) require lower extremity immobilization for an extended period of time. Periods of immobilization combined with surgery have been associated with decreased muscle mass and bone mineral density (BMD).

The purpose of this study was to characterize postoperative body composition and BMD changes after arthroscopy for FAI. It was hypothesized that both lean mass and BMD would decrease postoperatively and then normalize over time.

Case series; Level of evidence, 4.

This was a retrospective review of 23 National Collegiate Athletic Association Division I athletes who underwent hip arthroscopy between 2017 and 2019 and had a dual-energy x-ray absorptiometry scan preoperatively and at 3, 6, 12, or 24 months postoperatively. Linear mixed-effects models were used to compare pre- with postoperative lean and fat mass values for the total body and total leg (both operative and nonoperative sides) as well as trunk, pelvic, and spinal BMD. For total-leg, femur, and femoral BMD, linear mixed-effects models were used to evaluate the influence of time, side (operative vs nonoperative), and their interaction on each outcome measure.

Regarding pelvic BMD, compared with baseline (mean, 1.41 g/cm² [95% CI, 1.33-1.49]), significant decreases were seen at postoperative 3 months (mean, 1.36 g/cm² [95% CI, 1.28-1.45 g/cm²]; P < .001) and 6 months (mean, 1.39 g/cm² [95% CI, 1.27-1.52 g/cm²]; P < .01) but not at 12 months (mean, 1.42 g/cm² [95% CI, 1.33-1.51 g/cm²]; P = .319). Total-leg BMD for the operative side increased significantly from baseline (mean, 1.52 g/cm² [95% CI, 1.43-1.61 g/cm²]) to ≥2 years postoperatively (mean, 1.56 g/cm² [95% CI, 1.47-1.65 g/cm²]) (P = .005). Combined leg fat mass was increased from baseline (mean, 6427 g [95% CI, 4855-7999 g]) to ≥2 years (mean, 11645 g [95% CI, 7845-15,446 g]) (P < .01). There were no significant differences in total-body fat or lean mass or combined-leg lean mass.

In this patient population, a postoperative decrease in pelvic BMD that resolved by 12 months and an increase in total-leg BMD on the operative side at ≥2 years were observed. While hip arthroscopy for FAI may have significant benefits for long-term body composition and bone mass, clinicians should be aware of the potential implications of decreased bone mass for up to 12 months postoperatively.