Clavicular Length: The Assumption of Symmetry

Abstract

Recent studies have shown subjectively worse outcomes associated with 15 to 20 mm of clavicle shortening. As a result, more than 15 mm of shortening has become a relative indication for operative management. Various methods to quantify shortening have been described in the literature. All measurement techniques described assume clavicular symmetry to assess clavicular shortening. The goal of this study was to assess the side-to-side variation in clavicle length in uninjured, skeletally mature adults.Clavicle length in 102 skeletally mature adults (age range, 22-91 years) was measured using computed tomography data. Clavicle length was defined as the distance between the lateral-most point of the clavicle in the acromioclavicular joint and the medial-most point of the clavicle in the sternoclavicular joint. The side-to-side difference in clavicular length was analyzed, and patients were organized into 2 groups: group 1 was symmetric (difference of less than 5 mm), and group 2 was asymmetric (difference of more than 5 mm). Mean difference in clavicle length for all patients was 4.25±3.8 mm (range, 0-23 mm). Clavicular symmetry was found in 73 (71.5%) of 102 patients. The remaining 29 patients had asymmetry greater than 5 mm. Asymmetry greater than 10 mm was found in 7 (7%) of 102 patients. Twenty-eight percent of clavicles were asymmetric, whereas 7% had clinically significant asymmetry that could affect treatment decisions.This finding calls into question previous methods developed to assess clavicular length in the setting of trauma because of the assumption of symmetry. Further studies are needed to evaluate the effect of hand dominance and pediatric trauma on this observation.