Safety and Efficacy of Posterior Instrumentation for Patients with Congenital Scoliosis and Spinal Dysraphism

Purpose: To evaluate the safety and efficacy of posterior segmental instrumentation and correction of congenital scoliosis with accompanying spinal dysraphism.

Materials and Methods: Retrospective analysis of the efficacy and documentation of the intra and postoperative complications were performed for consecutive patients. SRS-22 questionnaires were used to analyze the health related quality of life at the final follow-up (f/up). Inclusion criteria were patients with congenital scoliosis and spinal dysraphism who were treated with long segment instrumentation (more than 6 functional units) with at least two years of f/up. Patients with pure kyphosis, short instrumentation and those without any spinal dysraphism were excluded.

Twenty-two (18 female, 4 male) of 29 patients with 2 years of f/up formed the basis of the study. Average age of the patients was 12 (7-18) and average follow-up was 3.1 (2-10) years. Type of spinal dysraphism was diastematomyelia in 20 patients and syringomyelia in 2 patients. Twelve patients had previous and 3 patients had simultaneous surgeries due to spinal dysraphism. Two patients had previous anterior and posterior insitu fusion for deformity. 8 patients had mild neurological abnormalities before posterior instrumentation. All patients were ambulatory before surgery. Only posterior instrumentation was performed in 11 patients, wheras in the other 11, combined anterior release and fusion was done. Halo traction was used in 2 patients in between the anterior release and posterior instrumentation. Anterior release included discectomies in all patients and osteotomies in 3 patients. The posterior release included chevron in 7 and decancellation osteotomies in 4 patients. Posterior arc resection was performed in one patient. All patients had a combination of hooks and pedicle screws. Sublaminar wiring was used in 4 patients while spinous process wiring was used in 9 patients. Cancellous allograft was used in 17 patients for posterior fusion. The average operating time was 4.2 (2.5-7.5) hours for posterior procedures and 2 (1.5-2.5) hours for anterior procedures. Results: The major curve was corrected from a pre-op average of 71 (42-114) degrees to post-op 40 (12-65) degrees (43.6%). The compensatory curves were corrected from a pre-op average of 47 (16-85) degrees to a post-op 25 (15-48) degrees (46.8%). The average loss of correction between the post-op and final follow-up period was 2.2 degrees for major and 3.5 degrees for the compensatory curve. The average scores for the five domains of SRS-22 were 3.5 (2-4.75) for function, 3.9 (2.4-4.6) for pain, 3.5 (2.6-4.6) for self-image, 3.6 (2.6-5) for mental health, 3.9 (1-5) for satisfaction and 3.6 (2.85-4.4) for total.

One patient had a paraparesia associated with misplaced upper thoracic pedicle screws with total recovery after revision, one ambulatory patient with neuruological compromise had deterioration in her neurological status only to recover partially. Two patients had superficial and 1 patient had a deep infection for which an implant removal was necessary. Implant failure with pseudoarthrosis occurred in one patient who was managed successfully by a revision surgery. Five additional interventions in three patients were performed to manage complications.

Conclusion: This is the largest and most homogeneous series analyzing the safety and efficacy of posterior segmental instrumentation for patients with congenital scoliosis and accompanying spinal dysraphism. Spinal instrumentation was safe and efficient for this group of patients when translation, compression and vertebral column shortening were the basic maneuvers to realign the spinal column, avoiding distraction forces.