Multi-slice spiral CT 3-dimensional reconstruction technique to treat multi-segmental degenerative spinal stenosis with traumatic instability of lower cervical spine

Abstract

To study the feasibility of multi-slice spiral computed tomography (MSCT) 3-dimensional reconstruction technique in assisting cervical pedicle screw fixation (PSF) and double-door laminoplasty to treat multi-segmental degenerative spinal stenosis with traumatic instability (MDSTI) of lower cervical spine. From September 2006 to August 2007, PSF combined with double-door laminoplasty was performed in 9 patients with MDSTI of lower cervical spine. MSCT 3-dimensional reconstruction techniques, including volume rendering (VR) and multi-planar reconstruction (MPR), were used to assist preoperative diagnosis and measurement to guide the procedure. MPR was performed after operation. In coronal view, the degree of screw perforation was measured precisely and the different positions of pedicle screws were divided into three grades according to Richter's method. In axial view, the canal sagittal diameter and transverse area of every laminoplasty level were measured. Nine patients with MDSTI of lower cervical spine underwent PSF (total 44 screws). According to the classification of Richter, 72.7% (32/44) was in Grade 1 and 27.3% (12/44) was in Grade 2. No screw perforation occurred in Grade 3 and no screw revision was done for misplacement. No iatrogenic damage was observed. Double-door laminoplasty was performed in total 42 volumes. The postoperative sagittal diameter and transverse area of cervical spinal canal were significantly increased (P<0.05). The confidence intervals of mean increased ratio were 23.43%-40.65% in sagittal diameter and 23.18%-42.07% in transverse area. Six months after laminoplasty, based on MSCT axial view, complete union between "open door" and allograft bone was obtained in 76.19% of volumes (32/42), and allograft bone was absorbed partly in 23.81% (10/42). A solid union in bilateral gutters was achieved in all cases. They were followed up from 6 months to 1 year (mean 7.8 months). Postoperative neural function recovery in two cases improved 2 ASIA grade, 5 cases improved 1 grade and 2 cases remained the same as preoperative grade. No cases had lower ASIA grade. Assisted with MSCT 3-dimensional reconstruction technique, PSF combined with double-door laminoplasty can be performed more safely and effectively to treat patients with MDSTI of lower cervical spine.