Background: To improve the primary operative treatment of complex olecranon fractures we searched for new conclusive parameters. We hypothesized that the intermediate fragment plays a critical role for precise restoration of the trochlear notch contour and good outcome of initial operative treatment.

Methods: 58 patients (26 female, 32 male; mean age 55 years) with multi-fragmentary olecranon fracture were identified in a seven-year-period from trauma unit files at two European Level 1 trauma institutions. Retrospective review of all operative reports and radiographs/computed tomography scans identified patients with an intermediate fragment.

Results: 28 patients were treated with stable internal fixation using figure-of-eight tension-band wire fixation and 30 patients using posterior plate osteosynthesis with and without intramedullary screw. An intermediate fragment was seen in 36 patients (62 %). In 17 of these 36 patients (47 %), the intermediate fragment was described in operative report. Twelve of these patients (71 %) were treated with single posterior plate with/without an intramedullary screw, and five patients (29 %) with figure-of-eight tension-band wire fixation.

Conclusion: Fracture analysis identified an intermediate fracture fragment in the majority of patients with complex olecranon fractures. In diagnostic work up a CT scan should be used to assess the fracture pattern and to detect an intermediate fragment. This study suggests that identification, desimpaction and anatomic reduction of the intermediate fragment are critical preconditions for anatomic restoration of the trochlear notch and good functional results. Precise description of the fracture pattern including presence of an intermediate fragment in the operative report is recommended.

Systemic factors are believed to be pivotal for the development of heterotopic ossification in severely-injured patients. In this study, cell cultures of putative target cells (human fibroblastic cells, osteoblastic cells (MG-63), and bone-marrow stromal cells (hBM)) were incubated with serum from ten consecutive polytraumatised patients taken from post-traumatic day 1 to day 21 and with serum from 12 healthy control subjects.

The serum from the polytraumatised patients significantly stimulated the proliferation of fibroblasts, MG-63 and of hBM cells. The activity of alkaline phosphatase in MG-63 and hBM cells was significantly decreased when exposed to the serum of the severely-injured patient. After three weeks in 3D cell cultures, matrix production and osteogenic gene expression of hBM cells were equal in the patient and control groups. However, the serum from the polytraumatised patients significantly decreased apoptosis of hBM cells compared with the control serum (4.3% vs 19.1%, p = 0.031).

Increased proliferation of osteoblastic cells and reduced apoptosis of osteoprogenitors may be responsible for increased osteogenesis in severely-injured patients.