SERUM TITANIUM LEVELS IN PATIENTS WITH MODULAR VERSUS NONMODULAR HIP PROSTHESES

Abstract

Purpose: The purpose of our study was to compare serum titanium levels in patients with the three-piece modular AcuMatch® and one-piece nonmodular Versys® titanium femoral components.

Methods: Blood samples were obtained at multiple time points for four years after the surgery in patients with the Versys® one-piece (47 patients) or AcuMatch® three-piece (70 patients) femoral stems. Control levels were measured in 20 patients without titanium implants. Titanium (Ti) levels were measured using high resolution inductively coupled-plasma mass spectroscopy by a technician blinded to the patient groups.

Results: Medium Ti was significantly lower in the control group (.21 & #61549;g/L), when compared to patients with one- and three-part stems at all follow-up periods (p < .02). At 1 and 2 years post-operatively, medium Ti levels in the three-part group (3.1 and 3.4 & #61549;g/L) were significantly higher than levels in the one-part group (1.7 and 1.6 & #61549;g/L) (p < .004). At 3 and 4 years, medium titanium levels were not significantly different in the one-part group (2.5 and 2.7 & #61549;g/L) when compared to the three-part group (3.5 and 3.1 & #61549;g/L) (p > .05).

Conclusions: The intraoperative flexibility provided by modular femoral stems may be offset by increased wear at modular junctions. Ti levels were significantly higher in patients with a highly modular three-part femoral stems at 1 and 2 years but no significant difference was found at 3 and 4 years postoperatively. Continued monitoring of these patients is warranted to determine if metal levels can be used to evaluate stem performance.