Exercise Tolerance in Children With Early Onset Scoliosis: Growing Rod Treatment “Graduates”

Study Design Prospectively enrolled early-onset scoliosis (EOS) patients undergoing growing rod treatment, who have had no surgery for >1 year and/or have received definitive fusion (growing rod “graduates”). Objectives To assess oxygen consumption during exercise and determine if a diminished conventional pulmonary function test (PFT) correlates with metabolic, pulmonary, and cardiovascular measures during exercise. Summary of Background Data Based on clinical impression and sequential PFT values, EOS patients who have undergone extensive treatment are thought to have limited capacity during exercise. The use of PFTs in this population has been a primary outcome measure of respiratory capacity; however, PFTs are dependent on effort, and thus subjective. This led us to find a new assessment of outcome, to better understand their pulmonary capacity. Methods Patients underwent oxygen consumption (VO₂) testing while walking at self-selected speed over-ground and during a graded exercise test. Maximal VO₂ was predicted in those who completed the test to 85% of maximal heart rate (HR). Statistical analysis included Mann-Whitney U test and Spearman correlation coefficient (α = 0.05). Results 12 patients participated. Over-ground walking showed that EOS graduates chose to walk at the same speed, but at a higher VO₂ Cost (0.28 mL/kg/m) than controls (0.22 mL/kg/m; p <.001). Treadmill exercise testing showed 9 of 12 subjects able to complete the 85% of predicted maximum protocol. The EOS group had lower VO₂ during the final stage (27.9 mL/kg/min) compared to controls (34.2 mL/kg/min; p =.021); however, their heart rate reached the same values. Subjects completing the protocol had lower predicted VO₂ max (38.5 mL/kg/min) compared with controls (45.0 mL/kg/min), but this was not significant. Conclusions Although PFT data suggest clinically relevant pulmonary compromise in EOS patients, the current study shows that these children are able to keep up with their peers in daily activities and also have the capacity to exercise. Level of Evidence Level II, therapeutic