Anatomy of the clavicle and its medullary canal: a computed tomography study

With recent literature indicating certain clavicle shaft fracture types are best treated surgically, there is renewed interest in the anatomy of the clavicle. Intramedullary fixation of clavicle fractures requires an adequate medullary canal to accommodate the fixation device used. This computed tomography anatomical study of the clavicle and its medullary canal describes its general anatomy and determines the suitability of its medullary canal to intramedullary fixation.

Four hundred and eighteen clavicles in 209 patients were examined using computed tomography imaging. The length and curvatures as well as the height and width of the clavicle and its canal at various predetermined points were measured. The start and end of the medullary canal from the sternal and acromial ends of the clavicle were determined. The data was grouped according to age, gender and lateralization. The average length of the clavicle was 151.15 mm with the average sternal and acromial curvature being 146° and 133°, respectively. The medullary canal starts on average 6.59 mm from the sternal end and ends 19.56 mm from the acromial end with the average height and width of the canal at the middle third being 5.61 and 6.63 mm, respectively.

The medullary canal of the clavicle is large enough to accommodate commonly used intramedullary devices in the majority of cases. The medullary canal extends far enough medially and laterally for an intramedullary device to adequately bridge most middle third clavicle fractures. An alternative surgical option should be available in theatre when treating females as the medullary canal is too small to pass an intramedullary device past the fracture site on rare occasions.