Morphological analysis of the proximal femurs in adults with developmental hip dysplasia: a computed tomographic study

Abstract

Objective To investigate the morphological characteristics of the proximal femurs in adults with developmental dysplasia of the hip (DDH) by CT three-dimensional reconstruction.Methods CT scans were obtained from 70 adults with DDH (76 hips) and 54 healthy controls (54 hips).Morphometric parameters of the femurs,including femoral head diameter,femoral head height,neck-shaft angle,femoral offset,femoral neck anteversion angle,coronal femoral canal diameter,sagittal femoral canal diameter,the longest femoral canal diameter,torsion angle of femur,the distance from the lesser trochanter to the isthmus and the canal flare index (CFI),were derived from CT reconstructions.These anatomical parameters were compared between the DDH hips and healthy hips to show the difference and correlation.Results The femoral head height,femoral offset,CFI and torsion angle of femur in DDH group and control group were 4.82±0.95 cm and 5.18±0.57 cm,2.66±0.74 cm and 3.16±0.51 cm,4.12±1.05 and 4.53±0.65,46.86°±49.53° and 66.38°±28.75°,respectively.There were statistical differences for parameters above.In DDH group,there was a positive correlation between femoral head height and femoral offset (r=0.491,P=0.000),while a negative correlation between femoral head diameter and femoral neck anteversion angle (r=-0.443,P=0.001).The scatter plots showed that the DDH patients had a large irregular variance in coronal torsion angle of femur.Conclusion The shape of the dysplastic femur is abnormal,and the preoperative CT evaluation of the proximal femur in DDH patients is necessary,which can provide valuable information for THA.Custom prostheses are recommended to fit the abnormal morphologic characteristics of the severely dysplastic femurs. Key words: Hip dislocation, congenital; Anatomy; Femur; Adult; Tomography, X-ray computed