[Effects of ultrasonic bone curettes combined with high-speed drills in posterior laminectomy and decompression procedure for severe thoracic spinal stenosis].

To evaluate the safety and efficacy of the combined use of ultrasonic bone curette with the high-speed drill in posterior laminectomy and decompression procedure for severe thoracic spinal stenosis, and propose the optimal cutting position for ultrasonic bone curette during the laminectomy. By observing and measuring the parameters of thoracic pedicle, lamina, inner wall of the vertebral canal and their relation with the surrounding structures on cadavers, we provided a morphological marker for laminectomy by an ultrasonic bone curette. Data of 19 patients with severe thoracic spinal stenosis treated by posterior laminectomy and decompression were collected from June 2017 to June 2018 in Shanghai Changzheng Hospital. There were 11 males and 8 females, aged (50±6) years. The patients received laminectomy with the combined use of ultrasonic bone curette and the high-speed drill (Group A, 10) or the use of ultrasonic bone curette alone (Group B, 9). Operational time of decompressive laminectomy, blood loss, as well as perioperative complications such as durotomy, cerebrospinal fluid leak, injury of the nerve root and spinal cord were recorded in these two groups. The improvement of symptoms and the decompression width of the spinal canal were evaluated after operation. Two independent samples -test was used for the comparison of two sets of continuous normal distribution data. We had done the measurement in 6 cadavers. The mean distance between the boundary of cancellous-cortical bone of lamina and the inner wall of spinal canal was (0.9±0.4) mm, and the distance between the boundary of cancellous-cortical bone of pedicle and the inner wall of the spinal canal was (1.2±0.6) mm. For the surgeries in groups A, the mean laminectomy time for each segment was (4.4±0.5) min, the mean width of posterior laminectomy was (21.8±0.5) mm; and for the surgeries in group B, the mean laminectomy time for each segment was (5.0±0.5) min, the mean width of posterior laminectomy was (19.9±1.0) mm; there were significant differences in laminectomy time for each segment and the width of posterior laminectomy between the two groups (-2.391, 3.491, both 0.05). There was one case of dura injury and one case of thoracic nerve root injury during the operation in group B. It is safer and more reliable for the combined use of ultrasonic bone curette with the high-speed drill in posterior laminectomy and decompression procedure for the severe thoracic spinal stenosis. The interface between the cortical bone and the medial edge of cancellous bone of the pedicle could be identified as the cutting mark for ultrasonic bone curette in this procedure.