Studies in fiber guided excimer laser surgery for cutting and drilling bone and meniscus

Abstract

Our experiments on transmitting high-power excimer laser pulses through optical fibers and our investigations on excimer laser ablation of hard tissue show the feasibility of using the excimer laser as an additional instrument in general and accident surgery involving minimal invasive surgery. By combining XeClexcimer lasers and tapered fused silica fibers we obtained output fluences up to 32 J/cm2 and ablation rates of 3 pdpulse of hard tissue. This enables us to cut bone and cartilage in a period of time which is suitable for clinical operations. Various experiments were carried out on cadavers in order to optimize the parameters of the excimer laser and fibers: e.g., wavelength, pulse duration, energy, repetition rate, fiber core diameter. The surfaces of the cut tissue are comparable to cuts with conventional instruments. No carbonisation was observed. The temperature increase is below 40°C in the tissue surrounding the laser spot. The healing rate of an excimer laser cut is not slower than mechanical treatments; the quality is comparable.

Cortical bone healing following laser osteotomy using 6.1 μm wavelength*

“…Studies of cortical bone healing following laser osteotomy have been reported for the 193 nm [4,5], 248 nm [2,5] and 308 nm [1,3] [6, 12±16] lasers. The in¯uence on bone healing of various continuous wave and pulse modes, using various irradiances and¯uences of these laser wavelengths, have been examined and compared to drill or osteotomy saw lesions, in a variety of rat and rabbit in vivo models.…”

“…One study, using a ®ber guided 308 nm excimer laser to ablate cortical bone under a water surface, reported no carbonization of the ablation site and a preliminary healing study that found no difference in healing of osteotomy holes drilled in rabbit tibia cortex with either the laser or mechanical instruments [3]. A recent report indicated good healing following 193 and 248 nm irradiation; however, no comparison was made to a mechanical cut control group, and no discussion was presented comparing these results to previous studies with these wavelengths where healing has been delayed [5].…”

System development and clinical studies with a scanning CO 2 laser osteotome

“…The laser beam can be tightly focused and its position controlled electronically, so that precise narrow cuts with arbitrary complicated geometry can be exactly planned and performed. Early attempts to cut bones with lasers have failed however, because of strong thermal side effects in case of continuous wave (cw) and long-pulsed carbon dioxide CO 2 lasers 1-5 or very low cutting rate with excimer lasers [6][7][8][9] . The difficulties arise, while about one third of the compact bone tissue volume consists of hard mineral crystals (T melt > 1000°C 10,11 ), which are embedded in a sensitive collagen matrix.…”

Generation of periodic surface structures on silica fibre surfaces using 405 nm CW diode lasers

“…When MMF are used for high-power excimer laser light delivery [8,9], the surface damage threshold of synthetic silica is the primary limit. Severe optical damage is observed at power densities above 1 GW/cm² for pulsed lasers [10].…”