Thoracic pedicle subtraction osteotomy in the treatment of severe pediatric deformities

Abstract

The traditional surgical treatment of severe spinal deformities, both in adult and pediatric patients, consisted of a 360° approach. Posterior-based spinal osteotomy has recently been reported as a useful and safe technique in maximizing kyphosis and/or kyphoscoliosis correction. It obviates the deleterious effects of an anterior approach and can increase the magnitude of correction both in the coronal and sagittal plane. There are few reports in the literature focusing on the surgical treatment of severe spinal deformities in large pediatric-only series (age <16 years old) by means of a posterior-based spinal osteotomy, with no consistent results on the use of a single posterior-based thoracic pedicle subtraction osteotomy in the treatment of such challenging group of patients. The purpose of the present study was to review our operative experience with pediatric patients undergoing a single level PSO for the correction of thoracic kyphosis/kyphoscoliosis in the region of the spinal cord (T12 and cephalad), and determine the safety and efficacy of posterior thoracic pedicle subtraction osteotomy (PSO) in the treatment of severe pediatric deformities. A retrospective review was performed on 12 consecutive pediatric patients (6 F, 6 M) treated by means of a posterior thoracic PSO between 2002 and 2006 in a single Institution. Average age at surgery was 12.6 years (range, 9-16), whereas the deformity was due to a severe juvenile idiopathic scoliosis in seven cases (average preoperative main thoracic 113°; 90-135); an infantile idiopathic scoliosis in two cases (preoperative main thoracic of 95° and 105°, respectively); a post-laminectomy kypho-scoliosis of 95° (for a intra-medullar ependimoma); an angular kypho-scoliosis due to a spondylo-epiphisary dysplasia (already operated on four times); and a sharp congenital kypho-scoliosis (already operated on by means of a anterior-posterior in situ fusion). In all patients a pedicle screws instrumentation was used, under continuous intra-operative neuromonitoring (SSEP, NMEP, EMG). At an average follow-up of 2.4 years (range, 2-6) the main thoracic curve showed a mean correction of 61°, or a 62.3% (range, 55-70%), with an average thoracic kyphosis of 38.5° (range, 30°-45°), for an overall correction of 65% (range, 60-72%). Mean estimated intra-operative blood loss accounted 19.3 cc/kg (range, 7.7-27.27). In a single case (a post-laminectomy kypho-scoliosis) a complete loss of NMEP occurred, promptly assessed by loosening of the initial correction, with a final negative wake-up test. No permanent neurologic damage, or instrumentation related complications, were observed. According to our experience, posterior-based thoracic pedicle subtraction osteotomies represent a valuable tool in the surgical treatment of severe pediatric spinal deformities, even in revision cases. A dramatic correction of both the coronal and sagittal profile may be achieved. Mandatory the use of a pedicle screws-only instrumentation and a continuous intra-operative neuromonitoring to obviate catastrophic neurologic complications.

Fig. 1

An infantile idiopathic scoliosis of 95°. 11 + 8 years; Female. a Satisfying correction on the Risser cast, b Radiographic and clinical result after a t-PSO at T10

Fig. 2

A post-laminectomy kypho-scoliosis of 95° (intra-medullar ependimoma). 11 + 8 years; Female. a Signs of spinal cord cavitation on MRI; Incomplete paraplegia at presentation. Satisfying correction on the Risser cast, b A complete loss of NMEP occurred during t-PSO at T8 closure, promptly assessed by loosening of the initial correction, with a final negative wake-up test. Complete resolution of pre-operative incomplete paraplegia by post-operative 3rd month

Fig. 3

A sharp congenital kypho-scoliosis of 85°. 9 + 6 years; Male. a Patient already operated on by means of a anterior–posterior in situ fusion four years before. Satisfying correction on the Risser cast, mainly on the sagittal profile, b Radiographic and clinical result after a t-PSO at T11