CONTROLLED LASER-ABLATION OF POLYMETHYL METHACRYLATE BONE-CEMENT

The increasing numbers of re-operations carried out on total hip repla cement patients causes considerable difficulty for orthopaedic surgeon s. One particular problem lies in the removal of the bone cement inser ted during the primary operation without causing damage to the bone. I n order to develop a method for differentiating between polymethyl met hacrylate (PMMA) bone cement and bone during laser ablation, the laser -induced fluorescence from PMMA. has been studied and compared to that from the bone. An Oriel multispec spectrometer was used to analyse an d record the radiation emitted during 248-nm excimer laser ablation. T here was high-intensity fluorescence from bone relative to that from P MMA and several peaks occurred in the spectrum of bone which were abse nt from that of PMMA. Monitoring of this emission has enabled controll ed laser ablation of bone cement in contact with bone to be achieved i n vitro with no damage to the naked eye.