Abstract
Objective
By retrospective analysis of clinical data, to find new risk factors for postoperative dislocation after total hip replacement and the dose-effect relationship when multiple factors work simultaneously.
Methods
A nested case-control study was used to collect the dislocated hips from 5513 primary hip replacement case from 2000 to 2012. Apart from the patients with given cause of dislocation, 39 dislocated hips from 38 cases were compared with 78 hip from 78 cases free from dislocation postoperatively, which matched by the admission time. The factors that may affect the prosthetic unstable was found by the univariate analysis, and then they were performed multivariate logistic regression analysis and evaluation of a dose-effect factors.
Results
The clinical scores between the two groups was no significant difference before and after surgery. Univariate analysis revealed the position of acetabular prosthesis (P = 0.05) and the big ball (P=0.01) differences were statistically significant. While patient with adduction deformity incorporating limb lengtheningā§2cm(P<0.01) or the knee valgus deformity incorporating pelvic obliquity (P=0.01), as well as bilateral cases (P=0.02) were also the risk factors for dislocation. Big head decrease the dislocation rate. Multivariate analysis confirmed these newly founded factors are more important than the classic factors in this group of patients.
Conclusion
Patients with hip adduction deformity combined with limb lengthening, knee valgus deformity combined with pelvic obliquity and bilateral pathological hip seem more predisposed to dislocation after total hip arthroplasty, who should be strengthened preoperative education and postoperative management to prevent.
Key Word
total hip arthroplasty, dislocation, multivariate analysis
