What Is the Cost of a "Cast Holiday" in Treating Children With Early Onset Scoliosis (EOS) With Elongation Derotation Flexion (EDF, "Mehta") Casting?

Introduction: Serial casting of children with early onset scoliosis (EOS) is an established treatment option. A break from cast treatment often called a "cast holiday," (CH) is often allowed by some centers, particularly over the summer months. The impact of CHs on treatment duration or outcome has not been examined. Methods: Institution review board approved retrospective review of children treated for EOS with elongation derotation flexion ("Mehta") casting at a children's hospital between 2001 and 2016 with a minimum of 2 years' follow-up. A CH was defined as a minimum of 4 weeks out of the cast, braced, or unbraced. The analysis was performed to determine the impact of a CH within the first 18 months of treatment. Separate analyses were performed for the entire cohort of children castedduring the study period, and then separately looking at idiopathic EOS in isolation. The impact of a CH was assessed in terms of the likelihood of achieving scoliosis <15 degrees at the final follow-up ("success"). Odds ratios were used to assess group differences between "success" ratios, and Studentttests assessed group differences for parametric data. Results: Ninety children met inclusion and exclusion criteria, 31 of whom took a CH during the first 18 months of treatment (34%). This included 59 patients with idiopathic EOS (66%), 18 with syndromic EOS, 5 congenital, and 1 neuromuscular. There were no statistically significant differences between CH and no CH groups. Forty-four percent of the no CH group achieved scoliosis <15 degrees at final follow-up, as opposed to 13% of the CH group, an odds ratio of 5.3 for success without a CH. When limited to children with idiopathic EOS, 56% achieved success in the no CH, versus only 22% in the group that took a CH, an odds ratio of 4.4 for success with no CH. Conclusion: This study demonstrates that children treated for EOS with serial casting who take a CH within the first 18 months of treatment are less likely to achieve scoliosis