Classification of scapular body fractures.

INTRODUCTION: The aim of this study is to present, on the basis of 3D CT reconstructions of 187 of scapular body fractures, a clinically oriented classification respecting the biomechanical architecture of the scapula.

METHODS: In a series of 375 scapula fractures we identified 187 body fractures in187 patients (157 men, 30 women) with the mean age of 48 years (range; 16100 years). 3D CT reconstructions were obtainedof all fractures, to allow an objective evaluation of the fracture pattern. A total of 46 patients were operated on and their intraoperative findings were correlated with 3D CT reconstructions. Scapular body fractures were deemed to be only those fractures that passed through the biomechanical body of the scapula, i.e. involved at least one of the pillars. Excluded from the study were fractures of the superior angle and of the superior border of the scapula as they were only marginal fractures leaving both pillars intact; scapular neck fractures defined as extra-articular two-part fractures of the lateral angle separating the glenoid from the scapular body; and fractures of the inferior angle of the scapula. Evaluation focused on the course of fracture lines, their relationship to the two pillars, and the number of fragments. A separate fragment was considered to be only such a fragment that carried part of the circumference of the biomechanical body. The intercalary fragmentsbroken off the central part of the infraspinous fossa were not included.

RESULTS: We identified three basic groups of scapular body fractures, i.e. those involving only the spinal pillar, those involving only the lateral pillar and fractures affecting both pillars. Our series included 12 fractures of the spinal pillar, of these in 8 cases the main fracture line passed vertically from the supraspinous fossa of the central part of the pillar toward the medial border of the infraspinous fossa; in 4 cases the scapular spine base was broken off the scapular body. In all the cases, the lateral pillar was left intact and fragments were displaced only insignificantly. Therefore all these fractures were treated non-operatively. A total of 143 fractures involved the lateral pillar. All of them were fractures of the infraspinous portion of the scapular body, i.e. the infraspinous fossa, with the main fracture line propagating from the lateral pillar. This fracture pattern was divided on the basis of the number of circumference fragments into three subtypes, namely two-part (88), three-part (31) and comminuted (24) fractures. Fractures of both pillars were recorded in 32 cases. This fracture had two patterns, one (11 fractures) with a fracture line running through the spinal pillar close to the spinomedial angle to the superior angle of the scapula, and the other (21 fractures) with the main fracture line passing through the weakened central part of the scapular spine. This comminuted type was the most severe injury to the scapular body. The fracture line always propagated through the weakened central part of the spinal pillar. The fracture of the lateral pillar was displaced in all cases more than that of the spinal pillar.

CONCLUSION: Classification of scapular body fractures based on involvement of the pillars of the scapular body is logical and simple. It always requires a 3D CT reconstruction, including subtraction of the surrounding bones. It respects the anatomical structure of the scapula and may serve also as a therapeutic guidance in preoperative planning.Key words: scapula scapula fractures scapular body fractures - classification classification of scapular body fractures.