Biomechanical study of the initial stability of acetabular cup with different acetabular rim defects for developmental dysplasia of hip
10.3760/cma.j.issn.0253-2352.2019.19.008
- VernacularTitle: 髋关节发育不良全髋关节置换术中髋臼覆盖率对臼杯初始稳定性的影响
- Author:
Guochun ZHA
1
;
Shuo FENG
;
Qiaoqiao MA
;
Zerui WU
;
Kaijin GUO
Author Information
1. Department of Orthopaedics, the Affiliated Hospital of Xuzhou Medical University, Xuzhou 221002, China
- Publication Type:Clinical Trail
- Keywords:
Hip dislocation, congenital;
Arthroplasty, replacement, hip;
Biomechanics;
Pelvis
- From:
Chinese Journal of Orthopaedics
2019;39(19):1215-1221
- CountryChina
- Language:Chinese
-
Abstract:
Objective:To investigate the effects of acetabular coverage on the initial stability of the cup during total hip arthroplasty in developmental dysplasia of hip.
Methods:There were 50 fourth-generation synthetic hemi-pelvises. The different cup coverage rate (100% group, 70% group, 60% group, 50% group, 40% group) was created in pelvis with 10 specimens per group. The synthetic hemi-pelvis was fixed rigidly to a customized fixture which was placed on the testing table of the material testing machine. Pull-out and torque test were conducted by computer-control in torsion testing machine.
Results:In the acetabular cup pull-out test, the average pull-out force for mode of failure in 100%, 70%, 60%, 50%, and 40% group was 1 560.4±438.7, 1 467.2±349.8, 1 137.8±427.4, 737.4±134.8, 506.6±119.0 N, respectively. The pull-out force was reduced gradually. The pull-out force in 100% group was significantly higher than that in 50% (P=0.004) and 40% (P=0.001) group. The pull-out force in 70% group was significantly higher than that in 50% group (P=0.002) and 40% group (P=0.000). The force in 40% group was significantly lower than that in 60% group (P=0.013) and 50% group (P=0.021). In the acetabular cup torque test, the average torque for mode of failure in 100%, 70%, 60%, 50%, and 40% group was 28.0±3.7, 17.0±2.2, 9.4±1.1, 7.6±1.1, 6.4±1.1 N·m, respectively. The torque was reduced gradually. The torque in 100% group was significantly higher than that in other groups (P<0.05). There was no significant difference between 50% and 40% group (P>0.05). The torque in other groups were similar (P>0.05).
Conclusion:The present biomechanical study showed that different acetabular cup coverage rate affected the initial stability of the cup. The highest initial stability was observed in the cup with a 100% of cup coverage rate. The cup could not obtain 100% coverage when with acetabular rim defect. We should try our best to make the cup coverage reach to 70%. The 70% coverage rate has sufficient initial stability to meet daily activities without increasing the cup loosening rate.
