Study design: This ongoing longitudinal study evaluates simultaneous radiographic and platelet calmodulin determinations for patients with idiopathic scoliosis who are skeletally immature.
Objectives: To determine whether platelet calmodulin levels correlate with curve progression and severity.
Summary of background data: A previous study based on a single calmodulin determination and a single radiograph identified higher calmodulin levels in progressive curves and in higher magnitude curves. A longitudinal study was needed to demonstrate the relation of calmodulin to curve changes for individual patients over time during the growth period.
Methods: In this study, 55 patients with idiopathic scoliosis of varying types and severity were followed longitudinally with serial radiographs and platelet calmodulin determinations. A Risser sign was recorded for each radiograph at each visit.
Results: Calmodulin levels increased in all the patients with progressive curves (13/13), remained stable in 73% of the patients with nonprogressive curves (11/15), and were higher generally in curves greater than 30 degrees and double structural curves. Calmodulin levels usually decreased in patients undergoing brace treatment (14/17) or spine fusion (9/10).
Conclusions: It appears that platelet calmodulin levels correlate closely with curve progression and stabilization by bracing or spine fusion. Correlation with nonprogressive curves was not as consistent, with 27% noncorrelation. Longer follow-up evaluation and enrollment of additional patients will be necessary to determine whether calmodulin may serve as a biochemical marker of curve progression and to help identify stable and progressive curves.