Osteosynthesis failure after the pedicle subtraction osteotomy for the correction of sagittal spine imbalance

Abstract

Purpose Pedicle substraction osteotomy (PSO) in the lumbar spine is indicated in the treatment of large sagittal deformities of the lumbar spine. Substantial complications associated with PSO's include pseudarthrosis and mechanical failure. The purpose of the present study was to assess the complications of this procedure and the causes of mechanical complications. Methods Fifteen patients aged between 38 and 79 years (mean age 63.8+/-12.82) were operated between June 2011 and September 2014 for sagittal imbalance by means of one-level PSO. Preoperative and postoperative value of radiological spino-pelvic sagittal parameters were measured. Clinical and radiological evaluations were conducted preoperatively and postoperatively at 6 months and 1 year. Clinical evaluation included intraand postoperative complications. Results Mean pelvic incidence was 54.86 ±11.82º. Lumbar lordosis (LL) was measured to 12.26 ±18.48º preoperatively and increased to 42.73 ±14.05º postoperatively (p<0.05). Mean gain of lordosis after PSO at index level (fig. 2), was calculated to 28 ± 11º [14–41º]. SVA decreased postoperatively from 93.46 ±36.69 mm to 61.73 ±38.68 mm (p<0.05). Several complications (n = 8), including 2 minor (one dural tear with no clinical consequences and one transient radicular deficit) and 6 major with reintervention were observed in our series. Conclusions The main cause of mechanical complications was insufficient sagittal correction. To limit the risk of mechanical complications and to achieve a good sagittal balance, PSO must be associated with additional SPO's or a second corrective surgery to obtain a solid anterior fusion.