Idiopathic Scoliosis: Complications 

Jean-Marc Mac-Thiong, M.D., PhD, FRCSC
Hôpital du Sacré-Cœur de Montréal
Montréal, QC 

Based on data from the US National Inpatient Sample (NIS) on 51,911 patients undergoing spinal fusion for idiopathic scoliosis between 1993 and 2002, the total inhospital complication rate was 14.9% for paediatric patients and 25.1% for adult patients7. The in-hospital mortality rate was 0.2% and 0.4% for paediatric and adult patients, respectively. Age, male gender, comorbidities, high ASA score, extent of fusion, performing a vertebral osteotomy, fusion down to the sacrum, and high preoperative curve magnitude can contribute to the increased risk of complications6,7. Interestingly, a study1 showed that perioperative outcomes and complications in scoliosis surgery were not influenced by the experience level of the surgical assistants, supporting the benefits of teaching scoliosis surgery to residents and fellows in academic centres.

 

For adolescent idiopathic scoliosis (AIS), a retrospective study from the Scoliosis Research Society (SRS) reported an overall complication rate of 5.7% in 6334 patients, including two deaths (0.03%)4. The authors also observed a significant increase in the overall and neurologic complication rates when combined anterior-posterior procedures were performed. Recently, a first prospective study from the Spinal Deformity Study Group (SDSG) on 702 patients undergoing surgical correction of AIS showed a non-neurologic complication rate of 15.4%, with respiratory complications, excessive bleeding, infections and other wound-related problems being the most common3. Age, body mass index, presence of cardiac or respiratory disease, previous surgery, pulmonary function, surgical approach, number of levels fused, graft material, use of diaphragmatic incision, curve type, and region of the major curve did not correlate with the increased prevalence of non-neurologic complications. However, increased blood loss as well as prolonged operative and anaesthesia times were associated with a higher prevalence of non-neurologic complications.

The complication mostly feared by patients and surgeons remains neurologic injury. There are many potential causes of neurologic deficits during or following scoliosis surgery2. One possible cause is mechanical - from extrinsic compression of the spinal cord by implants (hooks, wires, screws), an epidural hematoma or abscess, or intraoperatively - by direct iatrogenic injury to neural elements from an instrument. The second possible cause is infolding of ligamentum flavum, posterior longitudinal ligament or disc material due to correction manoeuvres. A third relates to the distraction of the spinal cord during correction, especially in the presence of increased thoracic kyphosis. A last potential cause comes from an ischemic injury resulting in reduction of the blood supply to the spinal cord. In the SRS report on AIS surgery4, neurologic complication rates were higher for combined procedures (1.75%) when compared to anterior-only (0.26%) or posterior-only procedures (0.32%). Of the 18 (0.3%) patients with a spinal cord injury, complete recovery was noted in 11, incomplete recovery in six, and no recovery in one. More recently, the SDSG reviewed 1301 cases of surgical treatment of AIS from their prospective database and reported nine (0.7%) neurologic complications, of which four were spinal cord injuries that resolved spontaneously within three months postop5. It should be underlined; however, that in this study, all surgeons were experienced spine surgeons performing at least ten cases per annum of AIS surgery. To reduce the risk and severity of neurologic complications, neuromonitoring using either somatosensory-evoked potentials (SSEP) or motor-evoked potentials (MEP) has become a standard of care in scoliosis surgery, replacing the Stagnara wake-up test. When a neurologic injury is recognized intraoperatively, optimizing blood pressure, hematocrit and oxygenation remain the first steps in order to minimize the risk of vascular ischemia. Then, based on a wake-up test, the decision to release or remove the instrumentation is made.

In summary, surgical treatment of idiopathic scoliosis is a safe procedure, but a thorough knowledge of potential complications - especially neurologic - and associated risk factors is essential for patient selection and counselling.

References 

  1. Auerbach J.D., Lonner B.S., Antoniacci M.D., et al. Perioperative outcomes and complications related to teaching residents and fellows in scoliosis surgery. Spine 2008;33:1113-1118
  2. Bridwell K., Lenke L.G., Baldus C., et al. Major intraoperative neurologic deficits in pediatric and adult spinal deformity patients: incidence and etiology at one institution. Spine 1998;23:324-331
  3. Carreon L.Y., Puno R.M., Lenke L.G., et al. Non-neurologic complications following surgery for adolescent idiopathic scoliosis. J Bone Joint Surg Am 2007;89:2427-2432
  4. Coe J.D., Arlet V., Donaldson W., et al. Complications in spinal fusion for adolescent idiopathic scoliosis in the New Millenium. A report of the Scoliosis Research Society Morbidity and Mortality Committee. Spine 2006;31:345-349
  5. Diab M., Smith A.R., Kuklo T.R., et al. Neural complications in the surgical treatment of adolescent idiopathic scoliosis. Spine 2007;32:2759-2763
  6. Guigui P., Blamoutier A., Groupe d'Étude de la Scoliose. Complications of surgical treatment of spinal deformities: a prospectve multicentric study of 3311 patients [Article in French]. Rev Chir Orthop Reparatrice Appar Mot 2005;91:314-327
  7. Patil C.G., Santaralli J, Lad S.P., et al. Inpatient complications, mortality, and discharge disposition after surgical correction of idiopathic scoliosis: a national perspective. Spine J 2008;8:904-91

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