Comparison of the ablation ability of the Nd:YAG laser to nucleus pulposus between different parameters

English Keywords:Percutaneous laser disc decompression  Laser parameters  Nucleus pulposus  Ablation potency  Goat

English Abstract:

  【Abstract】 Objective：To compare the laser ablation ability of the Nd:YAG laser（1064nm） to the nucleus pulposus between different parameters.Method：Fresh goat spines were selected to make 144 function units of the spine.The specimens were divided into 18 groups on random，8 specimens in each group.The laser was emitted intermittent in the former 9 groups（method A）.The total energy and the frequency was 250J/10Hz（group A1），250J/20Hz（group A2），250J/30Hz（group A3），500J/10Hz（group A4），500J/20Hz（group A5），500J/30Hz（group A6），750J/10Hz（group A7），750J/20Hz（group A8），750J/30Hz（group A9） respectively.The laser was emitted continuous in the latter 9 groups（method B）.The total energy and the frequency of each group was corresponding to method A.The intervertebral discs were radiated by Nd:YAG laser，the pulse width was 0.4ms，the power in each group was 10W.The laser was emitted lasting for 1s，and the interval time was 1s in group A.There was no interval time in group B.The weight of the specimen was measured before and after ablation，and the cavities were measured after radiating by sliding caliper after ablation.Result：At the same energy of method A，when the frequency was 20Hz，the ablated quantity and the long and wide axis of the cavity all exceeded 10Hz and 30Hz.At the same frequency，when the energy was 750J，the ablated quantity and the long and wide axis of the cavity all exceeded 250J and 500J.There was no interaction between frequency and energy.At the same frequency of method B，when the energy was 750J，the ablated quantity and wide axis of the cavity all exceeded 250J and 500J.There was no interaction between frequency and energy.When the energy was 750J and the frequency was 20Hz，the long axis of the cavity was largest.At the same parameter，the ablated quantity was greater in method B than method A when the parameter was 750J/30Hz，and the remaining groups were not statistically significant between the two methods.The long axis of the cavity was greater in method B than method A except when the parameters were 250J/30Hz，750J/20Hz and 750J/30Hz.The wide axis of the cavity was greater in the method B than method A when the parameters were 500J/10Hz and 500J/30Hz，and there was no statistically significant difference in the remaining groups between two methods.Conclusion：At the same parameter，both the quantity of ablation and the form of cavity are influenced by the mode of laser.The ablation ability is influenced by the different modes of the Nd:YAG laser when the parameter is changed.At the same energy，the ablation ability is influenced by the frequency of laser；at the same frequency，the ablation ability enhances with the increase of energy of laser.