Fatty infiltration of periarticular muscles in patients with osteonecrosis of the femoral head.

Abstract

Purpose: Muscle mass and fatty infiltration can be assessed on computed tomography (CT) images using the cross-sectional area (CSA) and computed tomography attenuation value (CTV). Femoral head collapse in osteonecrosis of the femoral head (ONFH) may affect both values. We investigated factors influencing the CSA and CTV of the periarticular muscles in patients with ONFH.

Methods: Overall, 101 patients with ONFH with unilateral hip pain (stage 2, 24 patients; stage 3 A, 49 patients; and stage 3B, 28 patients) were included. The CSA and mean CTV of the bilateral gluteus maximus (Gmax), gluteus medius (Gmed), gluteus minimus (Gmin), and iliopsoas (IP) muscles were measured using CT cross-sections. Bilateral comparisons and associations with Japanese Investigation Committee (JIC) stage were analysed. Multiple regression analysis was used to evaluate factors associated with the CSA and CTV.

Results: On the symptomatic side, the CSA was significantly lower for the Gmax, Gmed, and IP, whereas the CTV was significantly lower for all tested muscles (all p < 0.01). The CTV, but not the CSA, of the Gmax, Gmed, and Gmin was significantly associated with the JIC stage severity bilaterally (all p < 0.01). Multiple regression analysis showed significant associations of the CTV with age, sex, and JIC stage (all p < 0.01).

Conclusion: Symptomatic ONFH leads to decreased muscle mass and increased fatty infiltration. Femoral head collapse progression is associated with a decrease in the CTV. Periarticular muscle assessment, including on the contralateral side, is important in patients with ONFH, particularly in older women.