The classification of complex 4-part humeral fractures revisited: the missing fifth fragment and indications for surgery.

We describe a new classification of complex 4-part proximal humeral fractures (PHF). Its novelty lies in the involvement of fractures of the calcar area (i.e., the missing fifth fragment) in relation to fragments of the head, tuberosities and shaft. The classification consists of 6 groups (divided into 15 subgroups) of calcar fracture patterns. We hypothesized that this classification could aid surgical decision making in terms of osteosynthesis versus prothesis. To test this hypothesis, two shoulder surgeons, trained in the classification, re-examined the X-rays and CT scans of 100 cases of 4-part PHF to codify each calcar fracture pattern. CT scans proved to be essential for this process. We then theoretically assigned the most appropriate treatment to each subgroup. Subsequent verification of clinical records confirmed our hypothesis that this classification could help the surgeon to decide the best approach to complex 4-part PHF.