Review Question - QID 214004

Posteromedial calcar length of the humeral head less than 8 mm and a loss of medial hinge are among the most reliable predictors of ischemia in the surgical management of humeral head fractures.

Proximal humerus fractures are classified based on the Neer classification, in which 4 parts are described: greater tuberosity, lesser tuberosity, articular surface, and the shaft. A fragment is considered a part if it is greater than 45 degrees angulated or displaced >1cm. The posterior humeral circumflex artery is the main blood supply to the humeral head. Following ORIF, humeral head ischemia may occur and is associated with the initial fracture pattern. Several factors including <8mm of calcar length attached to the articular segment, disruption of the medial hinge, displacement >10mm and angulation >45 degrees have been associated with a disruption of the vascular supply to the humeral head.

Campochiaro et al review Hertel’s criteria of calcar length and medial hinge integrity and its reliability in predicting humeral head necrosis. They reported a 3.7% incidence of ischemia across all 267 fractures evaluated. In those patients that developed AVN, 30% had all of the predictors described by Hertel, however, in the non-AVN group, only 4.7% had these same findings. They concluded that while Hertel’s criteria are helpful, they may not be sufficient and the authors recommended 3-dimensional evaluation of any fracture involving the calcar.

Xu et al reviewed avascular necrosis in patients with proximal humerus fractures who were treated surgically. They reported on 291 patients throughout 7 studies in which there was no difference in the incidence of AVN for those treated surgically or nonoperatively. However, they concluded through subgroup analysis looking at different fixation constructs that, plate fixation specifically was associated with a higher risk of AVN than conservative management of proximal humerus fractures.

Figure A demonstrates a proximal humerus fracture with a medial calcar length of >8mm attached to the articular segment. Figure B is a proximal humerus fracture with a displaced greater tuberosity fragment. Figure C demonstrates a proximal humerus fracture with a medial calcar length of <8mm attached to the articular segment. Figure D is a displaced metadiaphyseal proximal humerus fracture in a skeletally immature patient. Figure E is a radiograph of a metadiaphyseal proximal humerus fracture in a skeletally mature patient with a medial calcar length >8mm.

Incorrect Answers:
Answer 1, 2, 5: These fracture patterns do not have the prognostic characteristics described by Hertel for humeral head ischemia: articular segment calcar length <8mm, displacement >10mm or angulation >45 degrees.
Answer 4: Humeral head ischemia is very rare following pediatric proximal humerus fractures.