The role of sternum in the etiopathogenesis of Scheuermann disease of the thoracic spine.

STUDY DESIGN: A clinical cohort study of sternum clinical measurements was performed in 10,057 students, during a school screening program for Scheuermann disease.

OBJECTIVE: To determine whether the length of sternum is correlated with Scheuermann disease pathogenesis.

SUMMARY OF BACKGROUND DATA: Many theories have been proposed for the etiology of Scheuermann disease, but the true cause remains unclear. Probably mechanical factors play a role in the development of the deformity. The reported success of brace treatment leads to the support to this theory.

METHODS: There were 5048 boys and 5009 girls. The mean age of children was 13,07 years (SD = +/-0.82). Scheuermann disease was detected clinically and was documented with lateral radiograph of spinal column. All children were measured for their sternum's length from the jugular notch until the top of xiphoid process. This measure was repeated 3 times for each child. The height of all students and the arm span were measured, as well.

RESULTS: In total 10,057 students screened, children with Scheuermann disease (study group) were 175 (147 men and 28 women). The length of sternum was greater in the healthy (control) group. There was a statistically significant difference between the 2 groups with regard to the sternum's length (Mann-Whitney U test, P = 0000). This is of particular importance, because in 2 groups that were comparable according to age (Mann-Whitney U test, P = 0605), the children with Scheuermann disease were taller in relation with the control group (Mann-Whitney U test, P = 0000).

CONCLUSION: The smaller length of sternum than the normal has a possible correlation with the appearance of Scheuermann disease. Probably the smaller length of sternum increases the compressive forces on the vertebral endplates anteriorly, allowing uneven growth of the vertebral bodies with wedging. More studies are required for the documentation of this theory of pathogenesis.