Morphological Analysis Of The Proximal Femurs In Adults With Developmental Hip Dysplasia

[Abstract] Objective:To explore the anatomy and clinical significance of the proximal femur with developmental dysplasia of the hip (DDH) by reconstruction of computed tomographic (CT) scans. Methods:CT scans were obtained from 70 adults with DDH (76 hips) and 54 healthy controls(54 hips). Morphometric parameters of the femur including femoral head diameter and hcight, neck-shaft angle, offset, femoral neck anteversion, coronal view canal width, sagittal view canal width, the longest canal width, canal rotation, distance from the lesser trochanter to the canal isthmus and the canal flare index (CFI) were derived from CT reconstructions. These anatomical parameters were investigated between the DDH hip and healthy hip to show the difference and the correction. Results:Compared with normal femurs, the dysplastic femurs had shorter head height (4.82±0.95cm vs.5.18±0.57cm, P=0.031), offset (2.66±0.74cm vs.3.16±0.51cm, P=0.001) and smaller CFI (4.12±1.05 vs.4.53±0.65, P=0.032). The femoral canal were more rotational than the controls(46.86°±49.53°±vs.66.38°±28.75°, P=0.024). In DDH patients, femoral head height and offset was positively correlated (r=0.491 p< 0.001), while femoral head diameter and femoral neck anteversion,was nagetively correlated (r=-0.443 p=0.001). Scatter plots showing that canal rotation in DDH patients had a large variance and with no rules.Conclusions:The shape of dysplastic femurs are abnormal, and the preoperative CT evaluation of proximal femur in DDH patients is necessary, and it can provide valuable information for THA. Customized and modular prostheses are recommended to fit the abnormal morphologic characteristics of the severely dysplastic femurs.