Vitamin D levels and pain outcomes in adolescent idiopathic scoliosis patients undergoing spine fusion.

PURPOSE: Prior research has indicated adolescent idiopathic scoliosis (AIS) patients have lower bone mineral density and lower vitamin D levels than healthy peers. Vitamin D deficiency has been associated with higher levels of pain. This study investigated whether vitamin D-deficient AIS patients had higher pain before or immediately after posterior spine fusion (PSF) surgery. METHODS: 25-Hydroxy vitamin D levels were tested in all AIS patients at their pre-operative appointment. Patients were grouped by serum 25-hydroxy vitamin D level: deficient, < 20 ng/mL; insufficient, 20-29 ng/mL; sufficient, ≥ 30 ng/mL. Primary outcomes included pre-operative Scoliosis Research Society Health-Related Quality of Life (SRS-30) and numeric rating scale (NRS) scores (0-10) up to 72 h post-operatively, and analyzed using ANOVA and linear mixed modeling, respectively. 176 patients undergoing PSF were included. Intra-operative characteristics by vitamin D status were also assessed. The cohort was 82% female and an average of 15.2 years (range 10.6-25.3 years) at fusion. Average major curve was 60 (range 40-104) degrees pre-operatively. RESULTS: Forty-five (26%) patients were deficient in vitamin D, 75 (43%) were insufficient, and 56 (32%) were sufficient. Patients with vitamin D deficiency had lower average household income by zip code (p < 0.01) and higher secondhand smoke exposure (p < 0.001). There were no differences in pre-operative SRS-30 score, pre- and post-operative major curve angles, or estimated blood loss across vitamin D groups. Trajectories of NRS indicated no differences in pain during the first 72 h after surgery. CONCLUSION: Vitamin D deficiency in this population is associated with potential markers of lower socioeconomic status; however, it does not influence AIS PSF patients' experience of pain before or immediately after spine fusion surgery. LEVEL OF EVIDENCE: II.

Does bracing for adolescent idiopathic scoliosis affect operative results?

STUDY DESIGN: Retrospective comparative study. OBJECTIVES: We hypothesize that preoperative bracing for idiopathic scoliosis results in increased stiffness, as measured by reduced correction on bending films, ultimately leading to decreased surgical correction. Bracing is the primary nonoperative treatment for immature AIS patients with mild to moderate curves. For patients who fail bracing and proceed to operative intervention, it is unknown whether their nonoperative treatment impacts their surgical results. METHODS: We conducted a single-center, retrospective, comparative study on 181 consecutive adolescent idiopathic scoliosis patients, aged 11-17 years, who underwent posterior spine fusion between 2011 and 2013. Patient flexibility was measured as percent change in the curve angle of the spine from standing to supine bend. Overall curve correction was calculated as the preoperative to postoperative change in standing coronal measure divided by the preoperative measurement and reported as a percentage. RESULTS: One hundred and twelve subjects (62%) underwent bracing prior to fusion. Braced patients had similar preoperative major Cobb angles than unbraced patients (56.5 vs 59.0, p = 0.07). Preoperatively, braced patients achieved less primary curve correction in bending films (33.6%) than unbraced patients (40.6%, p = 0.003). Postoperatively, Cobb angle correction was not different between the braced (75.7%) and unbraced group (77.2%) overall (p = 0.41). There was no difference in blood loss (p = 0.14) or surgical time (p = 0.96) between braced and unbraced groups when adjusted for surgeon and number of levels fused. CONCLUSIONS: While braced patients may demonstrate less preoperative flexibility, there is no evidence that braced patients experience decreased curve correction compared to unbraced patients. Bracing treatment did not impact operative results, as indicated by similar Cobb angle correction, estimated blood loss, and surgical time in both groups. LEVEL OF EVIDENCE: III.

Hemoglobin Levels Pre- and Posttreatment as a Surrogate for Disease Severity in Early-Onset Scoliosis.

STUDY DESIGN: Prospective cohort. OBJECTIVE: To compare preoperative hemoglobin levels to postoperative hemoglobin levels in patients with early-onset scoliosis (EOS). SUMMARY OF BACKGROUND DATA: Elevated hemoglobin (Hgb) may be a marker for preoperative hypoxia in patients with EOS and thoracic insufficiency syndrome (TIS). The changes in Hgb level after treatment may be a surrogate marker for improved oxygenation. METHODS: Because normal levels of Hgb vary with patient age, Hgb z scores were calculated by dividing age-adjusted mean Hgb levels by the age-adjusted standard deviation. Elevated Hgb was defined by a hemoglobin z score >1. Patients with a baseline Hgb value measured before initial implantation with at least one follow-up measurement, at 6, 12, or 18 months, were included in longitudinal analysis. Change in Hgb z score as well as change in curve magnitude over time was assessed using piecewise linear mixed modeling for patients with elevated Hgb and those without. RESULTS: Two hundred sixty-seven patients with EOS were treated surgically over the study period. Average age at initial implantation was 6.8 years. Forty-eight (18%; 95% confidence interval = 13.7%, 23.2%) subjects had an elevated Hgb (z score > 1) level before implantation procedure. Hgb levels decreased in subjects with elevated Hgb from implantation to 6 months (p < .001) with no change in Hgb from 6 to 12 months (p = .46) or from 12 to 18 months (p = .59), but an overall decrease from preoperative to 18 months (p < .001). There was no change in Hgb levels for subjects without elevated Hgb from implantation to 6 months (p = .94), from 6 to 12 months (p = .61), or from 12 to 18 months (p = .78). CONCLUSIONS: In some patients with EOS and TIS, there appears to be significant positive impact on oxygenation from distraction instrumentation as evidenced by a meaningful proxy measurement: improvement in abnormal preoperative Hgb levels after surgery. LEVEL OF EVIDENCE: III.