Complications in the Treatment of Adolescent Idiopathic Scoliosis

Introduction

Adolescent idiopathic scoliosis (AIS) is defined as a three-dimensional spinal deviation greater than 10 degrees occurring after the age of 10 years and before the musculoskeletal system has fully matured, with larger curves usually affecting girls over boys in a 10:1 ratio. The reported prevalence of AIS varies widely, but it averages between 2% and 3% in children under the age of 16 years, and 0.3% to 0.5% of these children will have a curvature of over 20 degrees, the curve magnitude at which treatment is generally recommended. The prevalence of AIS appears to be constant in different parts of the world. Although most patients can be effectively managed nonoperatively, some patients ultimately require surgical intervention. In general, surgery is warranted for high magnitude curves in skeletally immature patients or for major progression of a curve despite bracing. The goals of surgical treatment for AIS are to halt curve progression, maintain and restore balance, and correct deformity, while fusing the smallest number of motion segments.

Given the prevalence of AIS surgery, accurate and up-to-date complication data are crucial for surgical planning, preoperative counseling, and ongoing efforts to improve the safety of patients. Understanding the true incidence and causes of complications after AIS surgeries is important in shared decision-making among the surgeon, patients, and their families. This is particularly important for the correction of AIS, as the indication for surgery in most cases is prevention of curve progression rather than an imminent health concern, and such information can be used to develop strategies to minimize the incidence of complications. In this chapter we seek to describe complications related to the surgical treatment of AIS, overall management, best practices, and systematic measures for prevention.

Complications in Pediatric Spine Surgery: An Overview

Spinal surgery in children is associated with a range of complications depending on the type of operation. In a large multicenter, multisurgeon database study, Fu et al. reported on the morbidity profiles of different procedures and provided a perspective on the safety of spinal surgery performed in children. A total of 2040 complications were reported, for an overall complication rate of 8.5%. Infection was the most common source of morbidity, with an overall rate of 2.7%. Implant-related complications were reported in 1.6% of patients. Respiratory complications were the most common source of medical morbidity (0.9%). Hematomas and durotomies were less common, at 0.4% and 0.5%, respectively. Pulmonary embolus and deep venous thrombosis were relatively rare occurrences (0.03% each). The morbidity and mortality rates differed based on diagnosis. Patients treated for kyphosis or spondylolisthesis had the highest complication rates (15% and 10%, respectively), followed by patients treated for scoliosis (8%). The overall mortality rate was only 0.13% (1.3 per 1000 cases). Based on the Scoliosis Research Society (SRS) Morbidity and Mortality database, including 25,432 pediatric patients, the rate of mortality within 60 days of surgery was 1.3 per 1000 patients. The numbers of deaths per 1000 cases for pediatric patients aged 0 to 5 years, 6 to 10 years, 11 to 15 years, and 16 to 20 years were 2.02, 1.91, 1.19, and 0.95, respectively (P = 0.50). The rates of death were 0.2 to 0.32 per 1000. The mortality rates per for subtypes of scoliosis (deaths/1000 cases) were as follows: neuromuscular (3.5), congenital (2.9), idiopathic (0.2), other (1.4). In a review of 19,360 cases of pediatric scoliosis, Reames et al. identified complications occurring in 1971 (10.2%) cases, with a mortality rate of 0.13%. The overall complication rate for idiopathic scoliosis surgery was 6.3%, and the mortality rate was 0.02%. Complication rates differed significantly among idiopathic, congenital, and neuromuscular cases. Again, neuromuscular scoliosis had the highest rate of complications (17.9%), followed by congenital scoliosis (10.6%) and idiopathic scoliosis (6.3%). Neuromuscular scoliosis and congenital scoliosis had the highest rates of mortality (0.3% each), followed by idiopathic scoliosis (0.02%). Similar results were also demonstrated by Weiss et al. Multivariate analysis revealed age, gender, and comorbidities as significant factors affecting adverse outcome for pediatric patients presenting with idiopathic scoliosis, according to Patil et al.

The earliest estimates of complications associated with AIS surgery were derived from analyses of the SRS Morbidity and Mortality database. MacEwen et al. published the first report of SRS Morbidity and Mortality data in 1975 that assessed 7885 scoliosis cases treated by members between 1965 and 1971, aiming at analysis of acute neurological complications. The authors found an incidence of 0.72% of major neurological findings. Coe et al. in 2006, based on 6334 cases of AIS reported between 2001 and 2003, described an overall complication rate of 5.7% and a mortality rate of 0.03%. Combined anterior and posterior instrumentation and fusion had a significantly higher rate of complications (10.2%) and a significantly higher rate of neurologic complications (1.75%). Patil et al. reported a complication rate of 14.9% and a mortality rate of 0.17% based on 35,600 patients in a study using an inpatient care database that represents a 20% stratified sample of the US hospitals. In another study, by Carreon et al., a 15.4% rate of nonneurologic complications and a 0% mortality rate were reported from 702 pediatric patients surgically treated for AIS, though the short average duration of follow-up of 12 plus or minus 2 months prevented adequate assessment of late postoperative complications. Bartley et al. described a major complication rate of 5.4% in 3582 patients with a minimum of 4 to 6 weeks of follow-up, with a 2.6% perioperative complication rate and a 1.7% reoperation rate. Most complications were wound-related (0.98%), neurologic (0.53%), or instrumentation-related (0.42%). One death was reported (0.03%). Kwan and colleagues in 2020 published one of the largest cohorts of AIS patients analyzed for complications following surgery for AIS over the longest period. From an analysis of 84,320 patients undergoing surgery for AIS between 2004 and 2016, the overall complication rate was 1.5%. The three most common complication categories were surgical site infection (SSI) (0.52%), new neurological deficits (0.35%), and implant-related complications (0.21%). Magnitude of the primary curve, intraoperative blood loss, and age at surgery correlated weakly with the occurrence of complications. Comparison between the bookend periods showed that all complications had a decreasing trend.

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