Clinical anatomical study on high congenital dislocation of hip in adults

Objective To investigate the morphological anatomical abnormalities of high congenital dislocation of hip in adults and provide anatomical basis for the total hip arthroplasty(THA).Methods From May 1997 to July 2008,49 patients(57 hips) with high congenital dislocation of hip(Hartofi lakidis type III) were treated.There were 6 males and 43 females with an average age of 29.4 years old(18-56 years old).The locations were left in 24 hips and right in 33 hips.The morphological parameters(including femoral length,isthmus,height of femoral head center,neck-shaft angle,medial head offset,anteversion angle,canal flare index,anteroposterior diameter of the true acetabulum,posterior thickness of the true acetabulum,depth of the true acetabulum) of suffering hips(dislocation group,n=57) were measured by preoperative X-ray,CT and intraoperative clinical observation and were compared with those of contralateral hips(control group,n=41).The intraoperative situations of hip were observed.Results The height of dislocation was(45.41 ± 2.15) mm.The length difference of both lower extremities was(40.41 ± 2.02) mm.In dislocation group,isthmus was shortened;height of femoral head center,neck-shaft angle and medial head offset were decreased;and anteversion angle was increased.CT showed that the canal flare index was larger than 4.7,femoral shape was funnel-shaped according to Noble classifi cation.Anteroposterior diameter of the true acetabulum became smaller,posterior thickness of the true acetabulum became thicker,and depth of the true acetabulum was shallower.There were statistically signifi cant differences in the morphological parameters of femur and acetabulum between two groups(P 0.05).The intraoperative measurements showed that the anteroposterior diameter of acetabulum was(32.98 ± 1.02) mm and the depth of acetabulum was(14.21 ± 0.56) mm.There was no statistically signifi cant difference between intraoperative measurements and preoperative measurements(P 0.05).The acetabulum was full of fat and fi brous tissues.Running of the sciatic nerve in 40 cases were changed and it ran upward and laterally.Conclusion When high congenital dislocation of the hip in adults is treated with THA,anatomical variation must be fully taken into account.The acetabulum is expanded toward posterosuperior,excessive reamed should be avoided to prevent femoral fractures,and appropriate or tailor-made prosthesis was selected.