Abstract
BackgroundOsteotomies in the cervical spine are technically challenging. The purpose of this study was to evaluate the feasibility of the modified pedicle subtraction osteotomy (PSO) technique at C7 to be used for the treatment of cervicothoracic kyphosis secondary to ankylosing spondylitis.MethodsA total of 120 cervical spine computed tomography (CT) scans (of 82 male and 38 female patients) were evaluated. The scans were taken parallel to the middle sagittal plane and the sagittal plane intersecting the pedicles. Simulated osteotomy was performed by setting the apex of the wedge osteotomy at different points, and morphologic measurements were obtained. Seven patients with cervicothoracic kyphosis who underwent a modified PSO at C7 between May 2009 and June 2015 were retrospectively evaluated. The mean follow up was 32.9 months (range 21–54 months). Preoperative and postoperative chin-brow vertical angle (CBVA), sagittal vertical axis (SVA) and sagittal Cobb angle of the cervical region were reviewed. The outcomes were analyzed through various measures, which included the 36-Item Short Form Health Survey (SF-36) and a visual analog scale for neck pain.ResultsIn this morphometric study, a modified PSO was performed on 87 patients (59 male and 28 female) with a reasonable ratio of 72.5%. In the case series, radiographic parameters and health-related quality-of-life measures were found to show significant postoperative improvement in all patients. No major complications occurred, and no implant failures were noted until the latest follow up.ConclusionsThe modified PSO is a safe and valid alternative to the classic PSO, allowing for excellent correction of cervical kyphosis and improvement in health-related quality-of-life measures.
Highlights
Osteotomies in the cervical spine are technically challenging
A pedicle subtraction osteotomy (PSO) can achieve a mean correction of 30–40° according to the literature [12, 13], while Vertebral column decancellation (VCD) can achieve a mean correction of 83.8° [11]
PSO was performed at C7, due to this location being a safe location for the vertebral artery in front of the transverse process of C7, the size of the spinal canal at C7-T1, the mobility of the spinal cord and eighth cervical nerves in this region and the probability of preservation of reasonable hand function if a C8 nerve root injury were to occur [15]
Summary
Osteotomies in the cervical spine are technically challenging. The purpose of this study was to evaluate the feasibility of the modified pedicle subtraction osteotomy (PSO) technique at C7 to be used for the treatment of cervicothoracic kyphosis secondary to ankylosing spondylitis. Severe and rigid cervicothoracic kyphosis in patients with ankylosing spondylitis can cause pain, myelopathy, radiculopathy, marked limitation of horizontal gaze or upright posture, swallowing dysfunction leading to aspiration, as well as social impairment [1] For these patients, surgical correction and osteotomies are often required. Meng et al BMC Musculoskeletal Disorders (2020) 21:28 a PSO is performed using the retained anterior longitudinal ligament to act as a hinge to close the osteotomy [6] This differs from the technique of a VCD, where the hinge of the correction is located at the border of the anterior and medial column [10]. VCD includes osteoclasis of the anterior cortex of the osteotomised vertebrae, which decreases the need for shortening of the posterior column, reducing the risk of neurological deficits [14] This procedure has only been described for deformities of the thoracolumbar spine. Based on the technique of VCD, we modified PSO by shifting the hinge of correction backwards from the anterior longitudinal ligament
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