Development and validation of the new international classification for scapula fractures.

OBJECTIVES

Multiple scapula classification systems exist in the literature and were developed using a consensus approach with one or several experts agreeing on a classification without stringent validation. None have gained widespread acceptance. A decision was made by the OTA classification committee and the AO Classification Advisory Group to collaborate on the development of a new validated classification system capable of addressing the limitations of the existing systems.

METHODS

A feedback validation process through 4 iterations of revised classifications on radiographs and computed tomography (CT) scans was used. Statistical analyses calculated the proportion of agreement among surgeons and kappa statistics for the assessment of coding reliability. Estimates of classification accuracy were obtained using latent class modeling.

RESULTS

Fractures of the scapular neck are rare injuries and were difficult to define and diagnose with kappa values ranging from 0.28 to 0.40. Although fossa fractures could be identified on plain radiographs, specific fracture patterns could only be classified with CT scans. The new classification divides the scapula into 3 segments: fossa, body, and processes. The validation has shown that the classification can be reliable using plain radiographs (kappa 0.66), increasing to kappa of 0.78 when CT scans were added.

CONCLUSIONS

This basic coding system allows clinicians to describe and classify scapula fractures with a reasonable degree of reliability. This validated classification that has resulted from this process has been accepted by a disparate group of orthopaedic traumatologists as a better option for clinical communication and research documentation.