ANALYSIS OF SAGITTAL ALIGNMENT CORRECTION IN ANKYLOSING SPONDYLITIS USING THREE DIFFERENT OSTEOTOMY TECHNIQUES

Abstract

Introduction: Correction of lumbar spine deformity in ankylosing spondylitis (AS) can be achieved by pedicle subtraction osteotomy (PSO), polysegmental osteotomy (PO) or Smith-Petersen osteotomy (SPO). We report our results with these three techniques.

Methods: 26 males and 5 females with AS and average age of 54.7 years (range 40–74 years) underwent surgery for loss of sagittal balance, horizontal gaze and back pain. 12 patients underwent PSO, 10 SPO, and 9 PO. Osteotomy was carried out at L3 in PSO and SPO with pedicle fixation from T11 to S1. 9 patients with PO had osteotomy from L2–5 and fixation from T10-S1. Sagittal translation during corrective manoeuvre was controlled in 21 patients by application of temporary malleable rods, which were substituted with permanent rods. TLSO was used post-operatively for average period of three months. Mean follow-up was 4.2 years (range 1–9 years). Radiographic and clinical outcomes (ODI, VAS, SRS-22) were analysed.

Results: Mean kyphotic correction in PSO was 380 (range 250–490), in PO was 300 (range 280–400) and in SPO was 280 (range 240–380). The sacrohorizontal angle improved by 190(range 50–300) in PSO, 210 (range 80–280) in PO and 150 (range 50–180) in SPO. Outcome scores were better in PSO and PO as compared to SPO. Blood loss and transient nerve root palsy was slightly higher in PSO group. One patient with SPO had fatal bleeding as a result of aortic injury.

Conclusions: Regular use of temporary malleable rods is recommended to prevent sagittal translation during correction reducing the risk of neurological injury. Better correction of deformity was achieved with PSO and PO at the expense of increased blood loss. SPO can increase the risk of vascular injury, therefore we recommend PSO and PO for correction of deformity in Ankylosing Spondylitis.