Fracture line distribution of olecranon fractures.

PURPOSE: The association between specific olecranon fracture characteristics (e.g., displacement, fragmentation, subluxation) and fracture line distribution might help surgeons predict intra-articular fracture location based on fracture characteristics that can be determined on radiographs. We hypothesized that fracture mapping techniques would reveal different fracture patterns for minimally displaced fractures, displaced fractures, and fracture-dislocations of the olecranon.

METHODS: A consecutive series of 78 patients with olecranon fractures were evaluated using initial radiographs and computed tomography scans and characterized according to the Mayo classification. Fracture lines were identified based on reduced three-dimensional computed tomography reconstructions and graphically superimposed onto a standard template to create two-dimensional fracture maps. The fracture maps were then converted into fracture heat maps. Based on fracture and heat maps, fracture line location and patterns were determined.

RESULTS: Six (7.7%) patients had a non- or minimally displaced fracture, 22 (28%) a displaced fracture, and 50 (64%) a fracture-dislocation of the olecranon. There were 27 (54%) anterior and 23 (46%) posterior olecranon fracture-dislocations. Fracture lines of non- or minimally displaced fractures and posterior fracture-dislocations enter and exit the trochlear notch at the base of the coronoid, while fracture lines of displaced fractures and anterior fracture-dislocations were spread more broadly over the depths of the trochlear notch.

CONCLUSIONS: Based on fracture characteristics depicted on radiographs, one can anticipate the amount of the olecranon involved (how close is the fracture line to the coronoid) and the orientation of the fracture line. Computer tomography could be reserved for when more specific knowledge of the fracture line might affect treatment.

LEVEL OF EVIDENCE: III.