髋臼及股骨上端畸形致人工髋关节置换术后脱位原因及对策

目的：分析髋臼及股骨上端畸形致人工髋关节置换(THR)术后脱位的原因，探讨防治对策。方法：本组行全髋置换术172例后发生脱位5例(2．9％)，其中后脱位4例，前脱位1例。发生时间最早在术毕搬动时，最迟在术后第20天。脱位原因分析，4例存在先天性髋臼发育不良，前倾角过小，术中未能调整；1例为股骨上端畸形，假体头臼对合不良。结果：复位后牵引6周1例、髋人字石膏固定6周1例，手术调整前倾角2例、调整股骨假体柄1例，均未发生再脱位。结论：为避免发生脱位，术前CT平扫了解髋臼前倾角和股骨头包容程度，做好特殊假体准备；术中加大加深髋臼以增加臼杯的包容度，并调整股骨头、颈角度来配合对应关系。术中人工髋试活动稳定性良好是减少术后脱位保证。

Causes of Postoperative Dislocation after Total Hip Replacement Owing to Acetabular or Proximal Femoral Deformities and the Countemeasures

Objective:To analyse the causes of postoperative dislocation after total hip replacement (THR) owing to acetabular or proximal femoral deformities and to find the preventive measures.Methods:Of the 172 cases treated by THR postoperative dislocation after THR was found in 5 cases(2.9%).Posterior dislocation occurred in 4 cases and anterior dislocation occurred in 1 case.The postoperative dislocation occurred from immediately after operation when shifting the patient to 20 days after opration.Four cases had congenital dysplasia of acetabulum and too small anteversion angle,which was not adjusted during the operation and the other one had proximal femoral deformity and discongruency between prosthetic head and acetabulum.Results:Closed reduction was performed in two cases,followed by six week's traction or hip spica cast.2 cases were reduced operatively by adjusting the anteversion angle,and one by adjusting the prosthetic shaft.No redislocation was observed during the follow-up.Conclusion:To avoid the dislocation after THR,preoperative computer tomography plain scan can be used to judge the acetabular anteversion and the coverage on femoral head.Custom-made prosthesis should be provided before operation.The containment of socket may be increased by enlarging and deepening the acetabulum intraoperatively.The congruency between prosthetic head and acetabulum can be enhanced by adjusting the neck-shaft angle.The intraoperative trial stability of hip prosthesis will decrease the risk of dislocation.