BMI change following spinal fusion for neuromuscular scoliosis surgery.

Study Design: Retrospective descriptive, multi-center study.
Objectives: We hypothesize that a post-operative weight gain will result in patients who are underweight prior to surgery. Cachexia and low body mass index is common among children with cerebral palsy (CP). Many interventions are undertaken to assist the child in nourishment and to obtain a more normal body mass. Additionally, scoliosis is common among children with CP. In our practice we have noted weight gain post operatively in severely underweight children after spinal fusion.
Methods: We underwent a retrospective review of a CP cohort from a multicenter prospective registry. Percentiles on the CP specific growth chart for which each child belonged were plotted based on the patients' age, weight, gender, GMFCS level, and tube feeding status. We then assessed percentile change in patients between pre-op visit, 1 year, 2 years and for those with available data, 5 years follow up visits. Patients with under two years of follow up, patients with GMFCS III and below, and patients without weight data were excluded.
Results: We identified a total of 211 potentially eligible patients from a multicenter prospective registry. 109 had complete 2 years data to analyze and 37 patients had full 5 years data to analyze. We found that patients under the 50th percentile pre-operatively increased their percentile on the CP growth chart for weight 12.1 percentiles (95% CI 6.7, 17.5 p value < 0.001) whereas patients that began at the 50th percentile or above on average lost 2.2 percentiles (95% CI -6.8, 2.3) though the change was not statistically significant (p value 0.330). These changes appeared stable at 5 years. Although regression analysis showed that Cobb correction and pelvic obliquity correction, and hyperlordosis were not independent predictors of the change, we noted that patients with residual curves after surgery of 40° or more experienced 13.3 percentile less weight gain than those with better corrections.
Conclusions: Patients with CP are at risk for cachexia, malnutrition, reflux and other GI disorders. Data presented here suggests that corrective spinal surgery may improve weight percentile in patients who start out at 50th percentile and lower. Patients with 40° or greater of residual scoliosis may benefit less from spinal fusion than those with a better correction.
Level of Evidence: II; Prognostic retrospective cohort study.