The Trident® Ceramic Acetabular System
Safety of the ceramic-on-ceramic hip systems was established by studying the adverse (unfavorable) events within the clinical study. The adverse events experienced by patients who received the ceramic-on-ceramic hip systems (test group) were comparable to the adverse events experienced by patients who received a conventional, metal-on-polyethylene hip system (control group). There were no deaths in the test or control study groups. Additional surgery to replace or remove components occurred 4 times in the Trident® ceramic-on-ceramic group, as compared to 5 times in the metal-on-poly (control group). Analysis of the adverse event data demonstrated that there was no significant difference between the adverse events experienced in the test and control groups.
The effectiveness of the Trident® ceramic-on-ceramic systems was established by comparing the Harris Hip Scores (HHS) and the radiographic (X-ray) measurements of patients who received the ceramic-on-ceramic systems to those of patients who received the metal-on-polyethylene (control) hip system.
Pain and Function Improvement:
The Harris Hip Score is a scale from 1-100 that assesses a patient’s level of pain and function. The highest possible score (100) indicates pain relief and normal functional ability. The lowest possible score (0) indicates severe pain and disability. A score of 90-100 is considered excellent. At two years after surgery, the average Harris Hip Scores for the ceramic-on-ceramic group and for the control group were both in the excellent range.
X-ray (Radiographic) Measurements:
X-rays were reviewed at regular intervals after surgery to look for signs of possible device loosening, device movement, or accelerated wearing away of the components. At two years after surgery, all of the 185 Trident® cases evaluated were considered a radiographic success. No devices showed signs of device loosening, device movement, or accelerated wearing away of the components.
Patient Success Rates:
A patient was considered a success within the study if, at two years after surgery, the hip implant system was still in place (had not been replaced), the Harris Hip Score was greater than 70 points, and there were no x-ray signs that might indicate loose or unstable hip implant components. The patient success rate for the control group was 94%. The patient success rate for the Trident® ceramic-on-ceramic group was 97%.
Use for Inflammatory Joint Disease
The study results presented above include only patients who had primary total hip replacement for severe, non-inflammatory degenerative joint disease. Eight additional cases of inflammatory joint disease were enrolled in the study, and received a ceramic-on-ceramic system (either ABC or Trident®). The eight cases have been followed for a mean duration of 16 months. As of the latest functional evaluations, the mean HHS is 94 (range 85-100). There have been no reoperations or revisions. There have been no operative-hip-related complications. All components appear stable on X-ray.
The goals of artificial hip replacement include relief of pain, restoration of function, and correction of deformity. Ceramic-on-ceramic, however, demonstrates significantly lower wear versus conventional metal-on-plastic components in laboratory testing. Therefore, it is anticipated that these improved wear characteristics will result in a longer lasting implant.
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