DYE INCORPORATION TO ENHANCE THE LASER-ABLATION OF STANDARD AND REDUCED-MODULUS BONE CEMENTS

Laser ablation of acrylic bone cement is an alternative method of ceme nt removal that can be used during revision arthroplasty of cemented i mplants. This study investigated the feasibility of using a continuous -wave Argon ion laser (wavelength = 514 nm) with the addition of methy lene blue or red dye no. 13 to enhance the ablation of two types of bo ne cements: polymethylmethacrylate and polybutylmethylmethacrylate. Si x 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 A rgon laser was unable to ablate undyed polymethylmethacrylate or polyb utylmethylmethacrylate. However, ablation was shown for both cements w ith either dye. The red dye had a stronger absorption peak at 514 nm t han did the blue dye. Statistically larger ablation areas were seen fo r red polymethylmethacrylate than for blue polymethylmethacrylate (p < 0.013) at all levels tested. Ablation areas were larger in red than i n blue polybutylmethylmethacrylate cement. Blue polybutylmethylmethacr ylate cement produced larger ablation areas than did blue polymethylme thacrylate cements at all energy levels tested, with smaller surroundi ng 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 sma llest in red polybutylmethylmethacrylate cements at all test levels. T hese results suggest that, by using dyes to selectively alter the abso rption characteristics of bone cement, laser ablation can be an effect ive method for cement removal. Changes in the chemical structure of th e cement can also influence the response to laser treatment. Furthermo re, the absorption spectra of the bone cement can be altered to maximi ze energy absorption at a wavelength that is not absorbed by bone tiss ue; this potentially minimizes damage to bone during revision surgery.