Surgical treatment of post-traumatic kyphosis using modified pedicle subtraction osteotomy

Abstract

Background data Pedicle subtraction osteotomy (PSOS) is a pure closed wedge osteotomy that has been recently introduced for the correction of post-traumatic kyphosis (PTK). Modified PSOS uses the disc as part of the resected wedge together with the upper endplate, thus allowing excision of the degenerated disc material for better fusion and preventing failure. In PTK, the upper endplate is deficient and the upper disc is degenerated. Insertion of a spacer into the intervertebral gap ensures good bony contact and fusion and increases the angle of correction by making the correction in a manner of closed-open wedge rather than a pure closed wedge osteotomy. Purpose The aim of this work was to study the clinical and radiological results of surgical treatment of PTK using modified PSOS with insertion of a cage as a spacer into the intervertebral defect. Study design This was a prospective study conducted on 24 patients with symptomatic PTK. Patients and methods All patients were treated using the modified PSOS technique, with insertion of a cage into the intervertebral gap. Patients were assessed clinically and radiologically. Functional results were assessed using the Oswestry disability index (ODI) score and the Denis pain and work scale. Radiological assessment included local kyphosis angle and sagittal index immediately postoperatively and at the final follow-up, and the state of bony fusion and loss of correction at the last follow-up. Results The average follow-up period was 34.21 ± 4.47 (range 24-50 months). Local kyphosis angle improved from 39.08 ± 3.86° preoperatively to -0.25 ± 4.74° postoperatively, with insignificant change at the last follow-up. The sagittal index significantly improved from 41.33 ± 4.89° preoperatively to 1.81 ± 1.26° postoperatively, without significant change at the last follow-up. All patients showed solid bony fusion at the last follow-up. There were no major complications. All patients improved clinically as evidenced by improvement in pain and neurological status. Functional outcome significantly improved as evidenced by improvement in ODI score and return of most of the patients to their previous level of activity. Conclusion Modified PSOS is more anatomical, less technically demanding, and safe procedure that achieves good radiological and clinical outcomes with lower operative morbidity.