Abstract
Introduction
Trunnion wear has been reported as a cause for failure of modern total hip replacement implants. While there are several reports on the prevalence of trunnion corrosion with specific stem designs, little is known about the prevalence of this problem across other femoral stem designs. The purpose of this study is to review three commonly used uncemented femoral stems and to correlate any established risk factors with rates of revision.
Methods
We reviewed all patients followed prospectively over a 15-year period (March 2000 to September 2015) who underwent total hip arthroplasty with one of three modern uncemented femoral stem designs. All of the stems were made of titanium (Ti6Al4V alloy) with a 12/14 taper design. We included only metal (cobalt chromium) on highly cross-linked polyethylene articulations. We evaluated age, gender, body mass index (BMI), femoral head size, head length, neck angle and offset as potential risk factors for all cause revision and revision excluding infection by univariate analysis. We performed a logistic regression analysis with odds ratios (OR) for each parameter for both all cause revision as well as with infection excluded. We used a p value of <0.05 as a level of significance.
Results
A total of 2095 patients were included during the study period and had a minimum three-year follow-up. There were no differences in age, gender, or BMI across the three femoral component groups. There were no cases of trunnion wear or corrosion (with or without an associated adverse local tissue reaction) requiring revision identified across all three stem groups. Univariate logistic regression analysis demonstrated that head size was associated with increased risk of both all cause revision and revision excluding infection. Age, BMI, gender, offset and neck angle did not have significant association to all cause revision or to revisions excluding infection (p>0.05). Multivariate logistic regression controlling for age and BMI demonstrated that a femoral head size less than 32mm was associated with increased likelihood of all cause revision rates (OR 4.60 (95%CI 1.8, 11.8)) and revision excluding infection (OR 4.94 (95%CI 1.7, 14.41).
Conclusions
None of the patients who received one of the three modern uncemented femoral stem designs in this cohort demonstrated trunnion wear or corrosion requiring revision for adverse local soft tissue reactions. We recognize that low-levels of corrosion might exist in this cohort and therefore continued follow-up of these patients is required.
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