The use of acetabular fossa as a reference for achieying the anticipated inclination of the acetabular cup / 中华骨科杂志

ABSTRACT

Objective To discuss the anatomical and radiographic characteristics of acetabular fossa,and evaluate their value as a reference for achieving the anticipated inclination of the acetabular cup.Methods Sixteen adult normal pelvic specimens were studied.Central axis of acetabular fossa and its intersection with fossa edge and acetabular rim were marked.The radiographic appearance of the two intersections was evaluated.With radiographic templating,the relationship between the top of acetabular fossa and the central axis of acetabular cup at anticipated inclination was identified.Implantation of cementless acetabular cup was performed bilaterally on the pelvic specimens.The acetabular fossa was used as a reference for implantation on one side,and the acetabular positioning device was used on the other side.The discrepancy of acetabular inclination was recorded before and after operation in the two groups.Results Intersection of central axis of acetabular fossa with fossa top edge and acetabular rim corresponded to the most medial and lateral aspect of acetabular sourcil respectively on standard anteroposterior pelvic radiograph.There was close correlation between most medial aspect of acetabular sourcil and central axis of the acetabular cup at anticipated inclination of 40°±5°.For the group of using acetabular fossa as reference,the mean difference of inclination was 0.19°±3.14°(-6°-5°)before and after operation,and the discrepancy was 2.75°±2.89°(-2°-8°)for the control group.The difference between the two groups was statistically significant(t=-2.453,P=0.027).Conclusion In primary total hip replacement,if normal anatomy of acetabulum was found,the anticipated inclination of acetabular cup can be accurately obtained,based on the relationship between the top of acetabular fossa and anticipated inclination of acetabular cup on preoperative templating.