Imaging anatomical study and clinical application of transoral axis slide and rotation osteotomy technique / 中华骨科杂志

ABSTRACT

Objective:To introduce a novel technique note about anterior decompression through transoral axis slide and rotation osteotomy (ASRO) and identify its imaging parameters related to osteotomy, and to explore its clinical application value.Methods:CT data of cervical spine of 90 subjects were collected, including 54 males and 36 females. The age ranged from 26 to 72 years, with an average age of 48.7 years. The Mimics software was used to reconstruct the atlantoaxial three-dimensional model. We plan to perform osteotomy on both sides of the axis of the vertebral body in the anteroposterior direction and the ASRO related anatomical parameters were measured, including the minimum osteotomy angle, the maximum osteotomy angle, the minimum and maximumdistance between the osteotomy trajectory and the inner side of the articular surface, the length of the upper articular surface of the axis side mass, the depth of osteotomy at the highest point and lowest point of the axial osteotomy surface and the minimum osteotomy depth. A 56-year-old female patient was admitted to the hospital due to atlantoaxial dislocation with failure of occipital-cervical fusion, difficulty walking, weakness and hypoaesthesia in four limbs. Imaging revealed that narrow space between the transversal walking wire and upper-posterior of the odontoid process, compressing the spinal cord from the front and the back respectively. The ASRO technique was performed on the patient under neuro-electrophysiological monitoring, and the osteotomy angle, osteotomy depth, narrowest width of the upper cervical spinal canal, the medullary, spinal cord angle were measured and Japanese Orthopaedic Association Scores (JOA) cervical myelopathy evaluation were performed after the operation to evaluate the surgical treatment effect.Results:The minimum osteotomy angle and the maximum osteotomy angle was 14.7°± 4.36° and 33.0°± 8.67°. The minimum and maximumdistance between the osteotomy trajectory and the inner side of the articular surface, and the length of the upper articular surface of the axis side mass was 6.0±1.80 mm, 12.2±3.17 mm, and 17.2±1.90 mm, the ratio of the former two to the latter was 34%±8.7% and 70%± 15.0%. The depth of osteotomy at the upper edge, lower edge and narrowest place of the axial osteotomy surface were 6.0±1.80 mm, 12.2±3.17 mm and 17.2±1.90 mm. The postoperative imaging of the patient showed that the osteotomy angle was 17.1° on left side and 16.5° on right side, and the depth of osteotomy at the upper edge, lower edge and narrowest place of the axial osteotomy surface were 17.1 mm, 13.2 mm, and 9.1 mm on left side, and 17.4 mm, 11.8 mm, 8.46 mm on right side. All measured values met the ranges which were shown in the imaging anatomical study. The narrowest width of the upper cervical spinal canal increased from 6.58 mm to 15.28 mm, the medullary spinal cord angle increased from 131.7° to 153.8°postoperatively, and the cervical spine JOA score recovered from 6 points to 14 points, suggesting that the postoperative spinal canal space is obvious increased, the compression on the front of the spinal cord was significantly reduced. The patient's symptoms improved significantly.Conclusion:ASRO technique is a good choice for salvage of failed posterior occipitocervical fusion and some irreducible atlantoaxial dislocation because of the anterior bony fusion. It could direct decompress the spinal cord anteriorly, avoid the odontoid resection, which is a safe and feasible new technique.