COMPARISON OF CARBON-DIOXIDE LASER MODALITIES FOR REMOVAL OF POLYMETHYLMETHACRYLATE CEMENT

Polymethylmethacrylate (PMMA) cement is routinely used in a number of surgical procedures performed on human beings and animals. As the use of PMMA increases in veterinary medicine. the need for its removal dur ing surgeries also increases. indications for removal of PMMA are infe ction, aseptic loosening, and fracture of the cement. Polymethylmethac rylate cement is often applied in areas of the body where typical mech anical methods of removal are dangerous or impossible. Cement placed n ear the spinal canal for the treatment of caudal cervical malformation -malarticulation syndrome or deep within the femoral medullary canal f or total hip prostheses are examples. The ability to safely and easily remove cement should lower intraoperative complication rates associat ed with revision surgeries. The vaporization efficiency for removal of PMMA cement for three carbon dioxide laser modalities (continuous wav e only, with Swift-Lase(TM) attachment, and with Fiberlase(TM) wave gu ide) were determined, as well as heat transferred to periosteal surfac e during PMMA cement vaporization, and gross pathology to the cortical bone at the maximum vaporization efficiency power. Cefazolin sodium w as added to half of the samples to determine if the ablation rate of P MMA would be affected. The CO2 laser with wave guide was the most effi cient modality for vaporization at 25 watts, and produced significantl y less heat transfer to the periosteal surface than the heat of polyme rization of the PMMA cement. Cefazolin sodium appeared to slightly dec rease the vaporization efficiency, and all of the lasers produced gros s and histologic lesions to the bone.