Left Thoracic Scoliosis Configurations; Why So Different?

STUDY DESIGN: Patients in the scoliosis screening database were analyzed with respect to curve convexity, severity, and outcome, using standard statistical methods. OBJECTIVES: This study assessed whether left thoracic scoliosis is always pathologic and inquired why this is the case. SUMMARY OF BACKGROUND DATA: Left thoracic scoliosis is more significant than the usual right thoracic pattern, but evidence in the literature is circumstantial. METHODS: Prospectively collected data from 1979-1990 was analyzed in the natural history database of the school screening program. RESULTS: Right thoracic pattern was observed in 421 girls, and left thoracic pattern was present in 125 girls. The minimum age at diagnosis was 10 years and the Cobb angle was > 4 degrees. Primary left thoracic patterns were statistically smaller and less progressive. CONCLUSIONS: The left pattern of scoliosis in the absence of overt neuropathology carries a benign prognosis. This contradictory observation is examined in the light of biological asymmetry.