Dye incorporation to enhance the laser ablation of standard and reduced-modulus bone cements.

Abstract

Laser ablation of acrylic bone cement is an alternative method of cement removal that can be used during revision arthroplasty of cemented implants. This study investigated the feasibility of using a continuous-wave Argon ion laser (wavelength = 514 nm) with the addition of methylene blue or red dye no. 13 to enhance the ablation of two types of bone cements: polymethylmethacrylate and polybutylmethylmethacrylate. Six cement/dye combinations were studied while power (0.5, 0.75, and 1.0 W) and exposure times (30, 45, 60, and 90 seconds) were varied. The Argon laser was unable to ablate undyed polymethylmethacrylate or polybutylmethylmethacrylate. However, ablation was shown for both cements with either dye. The red dye had a stronger absorption peak at 514 nm than did the blue dye. Statistically larger ablation areas were seen for red polymethylmethacrylate than for blue polymethylmethacrylate (p < 0.013) at all levels tested. Ablation areas were larger in red than in blue polybutylmethylmethacrylate cement. Blue polybutylmethylmethacrylate cement produced larger ablation areas than did blue polymethylmethacrylate cements at all energy levels tested, with smaller surrounding damage areas. Red polybutylmethylmethacrylate cement also produced larger ablation areas than did red polymethylmethacrylate cement (at 0.75 and 1.0 W), again with smaller damage areas. Damage zones were smallest in red polybutylmethylmethacrylate cements at all test levels. These results suggest that, by using dyes to selectively alter the absorption characteristics of bone cement, laser ablation can be an effective method for cement removal. Changes in the chemical structure of the cement can also influence the response to laser treatment. Furthermore, the absorption spectra of the bone cement can be altered to maximize energy absorption at a wavelength that is not absorbed by bone tissue; this potentially minimizes damage to bone during revision surgery.