Seven studies were included in the review (586 patients, 769 hips). There were three RCTS and four non-RCTs. Mean quality score for RCTs was 6.3 (range 6 to 7) and for non-RCTs was 4.5 (range 4 to 5). Mean follow up was 89.2 months (range 60 to 155 months). Publication bias was reported in the clinical results for zirconia-polyethylene total hip arthroplasty.
The pooled risk difference of revision surgery was 0.05 (95% CI 0.02 to 0.08; seven studies), which indicated that zirconia-polyethylene total hip arthroplasties resulted in a statistically significant higher rate of revision surgery. There was some heterogeneity (I2=34.9%). When the source of heterogeneity was removed in sensitivity analysis, results still favoured the control intervention (risk difference 0.03; 95% CI 0.00 to 0.06; six studies), as did the analysis of three RCTs alone (although this was not statistically significant). Zirconia heads manufactured by Ceraver resulted in a higher rate of revision surgery (risk difference 0.08; 95% CI 0.03 to 0.14; I2=0%), but those manufactured by DePuy did not show any significant difference (three RCTs). Higher rates of revision were also noted in cemented total hip arthroplasties with zirconia heads (risk difference 0.06; 95% CI 0.02 to 0.10, I2=2.8%).
There was no statistically significant difference in mean annual polyethylene wear between zirconia head and control groups (five studies). Ceraver manufactured zirconia heads were not included in this analysis.