Higher femoral head–to–femoral neck ratio are associated with limited range of motion of hip joints in hereditary multiple exostosis patients

Abstract

Hip involvement is one of the most common skeletal manifestations of hereditary multiple exostoses (HME) in 30-90% of the patients. The anatomical changes in the proximal femur in patients with HME, may lead to deformities and related functional deficits. Its effect on the range of motion (ROM) of the hip joint is not well described. The aim of this study was to evaluate the role of hip deformity of HME disease in the ROM of the hip joint. It was hypothesized that certain morphological parameters affect the ROM of the hip joint. Conclusively, 44 patients including 27 men and 17 women (88 hips) were evaluated. Hips are divided in Group 1 (no ROM limitation group) and Group 2 (ROM limitation group). The head-neck ratio (HNR), center edge angle (CE), Sharp’s acetabular angle (SAA), alpha angle (AA), neck shaft angle (NSA) and ROM parameters were measured. The correlations between radiological parameters (SAA, CE, NSA, AA and HNR), and the ROM data (F, E, Abd, Add, IR and ER) were statistically evaluated. All evaluated parameters (SAA, CE, NSA, AA) except the HNR do not show significant differences between study group 1 (no ROM limitation group) and group 2 (ROM limitation group). The means of the HNR in group 1 were significantly higher than those in group 2 (HNR: 1.23 vs. 0.92, p<0.001). In group 2 HNR showed a strong positive correlation with Abd (PC 0.72, p<0.001), E (PC 0.7, p<0.001), ER (PC 0.67, p<0.001), IR (PC 0.67, p<0.001) and F (PC 0.66, p<0.001). HME patients with hip involvement have better ROM of the hip joint, if they have the higher HNR. Additionally, a positive correlation between HNR and ROM capacity was determined.