人工全髋关节置换术后脱位原因课件

人工全髋关节置换术后脱位 发生率 The average incidence of dislocation after total hip arthroplasty is approximately 3%. factors a history of previous hip surgery or revision total hip replacement （7.4%） a posterior surgical approach （5.8% vs 2.3%） faulty positioning of one or both components impingement of the femur on the pelvis or residual osteophytes impingement of the neck of the femoral component on the margin of the socket inadequate soft-tissue tension insufficient or weak abductor muscles avulsion or nonunion of the greater trochanter noncompliance or extremes of positioning in the perioperative period factors Age, height, and weight do not seem to be causative factors in many series, dislocation occurred in women more often than in men. a preoperative diagnosis of osteonecrosis, proximal femoral fracture or nonunion, or inflammatory arthritis. Likely contributing factors include extensive soft- tissue release, muscular weakness, small femoral head size (22 mm), and trochanteric nonunion. 后外侧入路脱位高发的原因 a tendency to retrovert the socket nadequate anterior retraction of the femur, so the acetabular positioning device is forced posteriorly during component insertion Division of all the short external rotators 防止发生脱位的策略 fixing the cup in the proper position judge the position of the patients pelvis in the horizontal and vertical planes women with broad hips and narrow shoulders men with a narrow pelvis and broad shoulders true position of the pelvis always must be taken into account 防止发生脱位的策略 The femoral component should be fixed with the neck in 5 to 10 degrees of anteversion（ 15 degrees is acceptable ） developmental dysplasia or juvenile rheumatoid arthritis, can cause error in judging the correct position （anteversion） Retroversion of the femoral neck may be encountered with slipped capital femoral epiphysis, or if the neck is resected at an excessively low level. 防止发生脱位的策略 Bone or cement protruding beyond the flat surface of the cup can cause impingement and must be removed after the cup has been fixed in place. if the greater trochanter is enlarged or distorted , some bone often must be removed from its anterior or posterior margin to prevent impingement. bony impingement is much more likely if femoral offset has not been adequately restored. The use of a femoral component with enhanced offset can be very beneficial in this situation 防止发生脱位的策略 components with larger diameter heads would seem to be more desirable than Charnley 22-mm head components the range of prosthetic motion and ultimate stability of the hip may be diminished if the longer neck requires the addition of a skirt to the head component modular liners is rotated into an inappropriate orientation. 防止发生脱位的策略 The adequacy of soft-tissue tension across the hip joint （延长1.5cm） dislocation decreased femoral offset （5mm） dislocation Trochanteric nonunion, with resultant diminished abductor tension, also has been associated with an increased incidence of dislocation Patient selection 类型 早期脱位：3 month Late dislocations are more likely to become recurrent and require surgical intervention. von Knoch et al. reported that 55% of late dis