Article

Defining Two Components of Shoulder Imbalance: Clavicle Tilt and Trapezial Prominence.

1Department of Orthopedic Surgery, Faculty of Medicine, the University of Tokyo, Tokyo, Japan 2Department of Orthopedic Surgery, Rady Children's Hospital and Health Center, San Diego, California.
Spine (Impact Factor: 2.45). 08/2012; 37(24). DOI: 10.1097/BRS.0b013e31826e2bbb
Source: PubMed

ABSTRACT Study Design. Single center; prospective case series.Objective. To examine two features of shoulder asymmetry (Clavicle Tilt and Trapezial Prominence) and their correlation to radiographic parameters.Summary of Background Data. Shoulder imbalance is one of the more notable aspects of clinical deformity due to scoliosis. However, a discrepancy between radiographic and clinical shoulder balance in adolescent idiopathic scoliosis (AIS) patients has been reported.Methods. A consecutive series of 113 pre-operative right main thoracic Lenke 1 and 2 AIS curves were included. Clavicle angle (tilt), trapezial angle, and ratio of left to right trapezial area were measured on clinical photos. These were correlated with radiographic measurements of T1 tilt, first rib angle, curve magnitudes, and thoracic and lumbar apical translation to C7 plumb line and CSVL.Results. The average age was 14.1yrs. There were 82 Lenke 1 and 31 Lenke 2 curves with an average thoracic Cobb of 52.1°. The clinical clavicle angle ranged from -10.6 to +5.2° ("+" defined as high on the left) and had modest correlation with T1 tilt, thoracic curve size, and thoracic apical deviation (r value, 0.417, 0.437, and 0.408). Medial shoulder trapezial prominence as by the trapezial angle (range: -16.7 to +9.9) and trapezial area ratio (natural log of ratio range; -1.15 to +0.80) correlated well with the radiographic measurements of T1 tilt, first rib angle, and upper thoracic curve size (trapezial angle: 0.713, 0.679, and 0.686; trapezial area ratio: 0.597, 0.595, and 0.653, respectively).Conclusion. Our analysis suggests there are two distinct regions (lateral and medial) of shoulder height asymmetry. Medial differences reflected in trapezial prominence relate to deformity created by upward tilted proximal ribs and T1 tilt. Lateral differences in shoulder symmetry as reflected in the clavicle angle correlate weakly with radiographic measures. This suggests correction of trapezial prominence may be more predictable compared to clavicle angulation following scoliosis surgery.

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