Abstract
Introduction
Failure of acetabular components has been reported to lead to large bone defects, which determine outcome and management after revision total hip arthroplasty (THA). Although Kerboull-type (KT) plate (KYOCERA Medical Corporation, Kyoto, Japan) has been used for compensating large bone loss, few studies have identified the critical risk factors for failure of revision THA using a KT plate. Therefore, the aim of this study is to evaluate the relationship between survival rates for radiological loosening and the results according to bone defect or type of graft.
Patients and methods
This study included patients underwent revision THA for aseptic loosening using cemented acetabular components with a KT plate between 2000 and 2012. Bone defects were filled with beta Tricalcium phosphate (TCP) granules between 2000 and 2003 and with Hydroxyapatite (HA) block between 2003 and 2009. Since 2009, we have used femoral head balk allografts. Hip function was evaluated by using the Japanese Orthopaedic Association (JOA) score and University of California, Los Angeles (UCLA) activity. Acetabular defects were classified according to the American Academy of Orthopedic Surgeons (AAOS) classification. The postoperative and final follow-up radiographs were compared to assess migration of the implant. Kaplan–Meier method for cumulative probabilities of radiographic failure rate, and the comparison of survivorship curves for various subgroups using the log-rank test were also evaluated. Logistic regression was performed to examine the association of such clinical factors as the age at the time of operation, body mass index, JOA score, UCLA activity score, and AAOS classification with radiographic failure. Odds ratios (ORs) and 95% CIs were calculated. Multivariate analysis was performed to adjust for potential confounders by clinical factors. Values of p < 0.05 were considered significant.
Results
The patient background is shown in Table 1. The JOA score at the final follow-up increased significantly (p < 0.001). Radiographic failure was evaluated for revision THA with beta-TCP, HA, and bulk allografts. These survival rates are shown in Table 2 and the rate in the AAOS type IV group was significantly lower than that in the type III group (p = 0.033). The survival curves were significantly different between beta -TCP group and bulk allograft group (p = 0.036) (Table 3). Multivariate analysis showed that AAOS type IV defect was found to be a risk factor for radiographic failure (radiographic failure: OR: 15.5, 95% CI: 1.4–175.4, p = 0.032)
Discussion
Our results of survival rate are similar to those reported by previous studies. However, by comparing the survival rates between beta-TCP group and bulk allograft group, beta-TCP is not suitable for bone graft reconstruction of acetabular bone defects with a KT plate. We also found that AAOS type IV to be a risk factor for failure of revision THA. Therefore, bone defect size is the critical risk factor for failure of revision THA using a KT plate. New devices and techniques for KT plates are needed to improve the treatment of pelvic discontinuity.
