Association between Changes in Sagittal X-ray Measurements and Neck Extensor Muscle Atrophy after Cervical Laminoplasty

BACKGROUND To investigate the association between neck extensor muscles (NEM) atrophy and changes in the sagittal cervical X-ray measurements after cervical laminoplasty. BASIC PROCEDURES This retrospective analysis was conducted on 64 patients who underwent cervical laminoplasty from March 2016 to March 2019. The preoperative and postoperative sagittal cervical X-ray images were measured, including the C2-C7 cobb angle, the C2-7 sagittal vertical axis (SVA), and the angle between the plane of the upper endplate of T1 vertebra and the horizontal plane (T1 slope). The preoperative and postoperative steatosis ratios of the NEM were measured using magnetic resonance images. MAIN FINDINGS There were significant differences between the preoperative and postoperative measurements of the C2-7 cobb angle, the C2-7 SVA, and the T1 slope (P < 0.05). The preoperative and postoperative steatosis ratios of each intervertebral level of the NEM also differed significantly (P < 0.05). The muscle atrophy ratio at C3/4 was positively correlated with the change in the C2-7 SVA (R = 0.646, P < 0.001) and negatively correlated with the change in the C2-7 cobb angle (R = -0.445, P < 0.001). The muscle atrophy ratio at C7/T1 was positively correlated with the T1 slope (R = 0.446, P < 0.001). CONCLUSIONS Muscle atrophy was more severe at the attachment points of the NEM (C3/4, C7T1). There was a significant association between the muscle atrophy ratio and the changes in sagittal cervical X-ray measurements.