Abstract
Ceramic-on-ceramic bearings are considered in several European and Asian countries a reliable alternative to metal-on-polyethylene, ceramic-on-polyethylene, or metal-on-metal (with small diameter heads) for total hip arthroplasty (THA) management. Reduced joint wear and limited peri-prosthetic osteolytic changes are the main reasons supporting the use of ceramic. So far, the available observational data show a low rate of revision following the use of Ceramic-on-Ceramic bearings, but concern remains regarding the risk of fracture and the prevalence of squeaking noises from the joint.
The objective of this study was to use a national arthroplasty registry to assess whether the choice of bearings – metal-on-polyethylene (MoP), ceramic-on-polyethylene (CoP), ceramic-on-ceramic (CoC), or metal-on-metal (MoM) – is associated with differences in the risk of revision.
Data from primary THAs were extracted from the New Zealand Joint Registry over a 15-year period. 97,889 hips were available for analysis. The mean age of patients was 68 years (SD +/− 11 years), and 52% were women. The median followup period in this patient population was 9 years (range, 1 to 15 years).
The primary endpoint was revision for any reason. Inclusion criteria were degenerative joint disease (84,894), exclusion criteria were previous surgery, trauma, and any other diagnosis (12,566). We also excluded patients operated on with a Ceramic-on-Metal THA, because of the small recorded number (429).
There were 54,409 (64.1%) MoP, 16,503 (19.4%) CoP, 9,051 (10.7%) CoC and 4,931 (5.8%) MoM hip arthroplasties. 3,555 hips were revised during the 15-year observation period. A multivariate assessment was carried out including the following risks factors available for analysis: age, gender, surgeon experience, use of cement.
Analysis of bearing surface type and revision showed a statistically significant lower risk for CoC hips (265 THAs, p≤0.01) when compared with CoP (537 THAs, HR 1.07, CI 0,92–1,26), MoP (2186 THAs, HR 1.39, CI 1.19–1,62), and MoM (576 THAs, HR 2.15, CI 1.84–2.51). The 15-year follow-up Kaplan-Meier survival analysis shows a 92% revision-free rate for CoC THAs (Figure 1). In particular, CoC THAs showed the lowest rates of revision for dislocation and for deep infection, when compared with the other bearings.
This registry study showed that the bearing surface is associated with the risk of revision. MoM bearing surfaces showed a high rate of revisions, while CoC THAs showed the lowest rate of revision compared to other bearing surfaces. Low wear and less osteolysis are the possible reasons for reduced risk of revision for aseptic loosening. We postulate that the healthy, fibrotic synovial-like pseudocapsule found in CoC THAs preserves the long-term stability of the joint and reduces the bio-burden for late deep infection. Future studies with larger data sets and longer follow-up should continue to investigate this query.
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