Severe persistent coronal imbalance following instrumented posterior spinal fusion for adolescent idiopathic scoliosis.

STUDY DESIGN: Retrospective case-control study. OBJECTIVE: The aim of this study was to identify the risk factors and health-related quality of life (HRQoL) impact of severe (> 4 cm) post-operative coronal imbalance at 2 years following posterior spinal fusion (PSF) for adolescent idiopathic scoliosis (AIS). Coronal imbalance is an unfavorable outcome following PSF for AIS, though the degree of imbalance in such patients is typically mild. We hypothesize that a small number of patients become and remain severely imbalanced post-operatively, though this phenomenon has not been well studied. METHODS: Prospectively collected data from a large multicenter registry were reviewed. Patients with severe coronal imbalance (SCIB; > 4 cm) 2 years after PSF were included. Matched controls without SCIB at 2 years were included at a 3:1 ratio. Comparisons were made between demographics, pre-operative radiographic measures, surgical factors, residual post-operative radiographic measures, and 2-year SRS-22 scores. RESULTS: Nine of 954 (0.9%) patients (88.9% females; mean age 14.8 ± 2.3 years) were found to be severely imbalanced at 2 years. These patients had significantly greater pre-operative bending thoracic curve magnitude (45° vs. 33°; p = 0.013), curve flexibility (22.9% vs. 63.3%; p = 0.004), and kyphosis (41° vs. 26.5°; p = 0.034) compared to matched controls. Pre-operative curve flexibility of < 20% was associated with a 23.8 times greater odds of SCIB (95% CI 2.1-250; p = 0.008). With respect to HRQoL, median SRS-22 pain (4.1 vs. 4.8; p = 0.041), self-image (3.9 vs. 4.6; p = 0.013), general function (4.5 vs. 5; p = 0.022), and total (4.1 vs. 4.7; p = 0.012) scores at 2 years were significantly lower in cases compared to controls. CONCLUSIONS: In the present study, thoracic curve stiffness was a strong risk factor for severe post-operative coronal imbalance, which was associated with poor HRQoL measures. Increased pre-operative thoracic curve stiffness (< 20% flexibility) should raise surgeon awareness for altering surgical approach to minimize the risk of severe post-operative coronal imbalance. LEVEL OF EVIDENCE: Level III.

Correlation between surgical site infection and classification of early onset scoliosis (C-EOS) in patients managed by rib-based distraction instrumentation.

OBJECTIVES: The aim of this study is to determine risk factors for infection among EOS patients treated by rib-based distraction instrumentation, and to further assess the incidence of infection among C-EOS categories and sub-types. Despite the heterogonous nature of early onset scoliosis, the classification of early onset scoliosis (C-EOS) has proven to have excellent reliability across its major categories. C-EOS's reliability has been verified; however, little data exist on the utility of this categorization in clinical decision-making and risk assessment. METHODS: After institutional review board approval, data for EOS patients treated by rib-based distraction instrumentation were collected between 2013 and 2017 in a single institution. Data collection included: major categories of early onset scoliosis classification (etiology, major curve and kyphosis), BMI, height, weight, procedure type, site of procedure, presence of tracheostomy, and bowel/urinary incontinence. RESULTS: 156 EOS patients underwent 843 rib-based distraction instrumentation procedures. 22.4% of patients (35/156 patients, 42 procedures) developed infections, 30/35 requiring irrigation and debridement. Type of procedure was significantly associated with infection rate, with rib-based distraction instrumentation insertion corresponding with the highest incidence of infection, as compared to instrumentation revisions or expansions (p = 0.006). Infection rates were also more common in shorter and lighter weight children (p = 0.001 and 0.03; respectively). Patients with a neuromuscular etiology had the highest rate of infection in comparison to congenital, syndromic, and idiopathic (5.7% vs, 4.9%, 4.7%, and 2.6%; respectively). Notably, high infection rates occurred neuromuscular hyper-kyphotic subjects (M+), occurring in all major curve C-EOS subgroups and at a rate of 8.3% for all procedures. CONCLUSION: Neuromuscular, larger magnitude major curve, and larger magnitude kyphotic angle C-EOS categories appear to be at a higher risk of infection. Such information potentiates the usefulness of C-EOS in surgical decision-making and in the informed consent process. LEVEL OF EVIDENCE: Level III therapeutic.