Association of findings on preoperative extension lateral cervical radiography with osteotomy type, approach, and postoperative cervical alignment after cervical deformity surgery

OBJECTIVE The authors’ objective was to determine whether preoperative lateral extension cervical spine radiography can be used to predict osteotomy type and postoperative alignment parameters after cervical spine deformity surgery. METHODS A total of 106 patients with cervical spine deformity were reviewed. Radiographic parameters on preoperative cervical neutral and extension lateral radiography were compared with 3-month postoperative radiographic alignment parameters. The parameters included T1 slope, C2 slope, C2–7 cervical lordosis, cervical sagittal vertical axis, and T1 slope minus cervical lordosis. Associations of radiographic parameters with osteotomy type and surgical approach were also assessed. RESULTS On extension lateral radiography, patients who underwent lower grade osteotomy had significantly lower T1 slope, T1 slope minus cervical lordosis, cervical sagittal vertical axis, and C2 slope. Patients who achieved more normal parameters on extension lateral radiography were more likely to undergo surgery via an anterior approach. Although baseline parameters were significantly different between neutral lateral and extension lateral radiographs, 3-month postoperative lateral and preoperative extension lateral radiographs were statistically similar for T1 slope minus cervical lordosis and C2 slope. CONCLUSIONS Radiographic parameters on preoperative extension lateral radiography were significantly associated with surgical approach and osteotomy grade and were similar to those on 3-month postoperative lateral radiography. These results demonstrated that extension lateral radiography is useful for preoperative planning and predicting postoperative alignment.