Review Question - QID 220023

The patient has a proximal humerus fracture-dislocation with disruption of the medial hinge and < 8mm of remaining calcar attached to the articular surface, which based on the original Hertel criteria, is a predictor for humeral head ischemia.

Proximal humerus fractures may occur at the surgical neck, anatomic neck, greater tuberosity, and lesser tuberosity, with two-part surgical neck fractures being the most common. Hertel published an initial set of five criteria reproduced in Illustration A that can be used to predict the likelihood of humeral head ischemia after a proximal humerus fracture, with the most important being <8 mm of calcar length attached to the articular segment. It is important to note that the predictors of humeral head ischemia do not necessarily guarantee progression to humeral head avascular necrosis with fixation, as there has been some suggestion in the literature that operative intervention within 48 hours post-injury may be beneficial and may not lead to AVN.

Johnson et al. reviewed proximal humerus fracture-dislocations managed by mini-open reduction and percutaneous screw fixation. The authors included 11 consecutive patients with three- and four-part proximal humeral fracture-dislocations using a mini-open deltopectoral approach with a horizontal split in subscapularis and found that only one patient developed avascular necrosis, while screw back out was seen in three patients, and no screw penetrations of the articular surface were seen. They concluded that their results were promising and comparable to published literature with an overall low rate of AVN.

Schnetzke et al. reviewed the rate of avascular necrosis after fracture-dislocations of the proximal humerus based on the timing of surgery. The authors retrospectively looked at 30 patients subdivided into groups of subjects operated on early (≤48 hours after trauma) and those with late surgery (>48 hours after trauma). They found at a mean follow-up of 37 months that ten patients (33%) developed a symptomatic AVN and ten patients underwent revision surgery, with all five patients undergoing late surgery developing AVN. They concluded that after late surgery, patients had a fivefold increased RR for AVN, suggesting that early surgery for fracture-dislocations of the proximal humerus within 48 hours of trauma significantly decreases the risk of AVN and subsequent surgery.

Figure A is an AP radiograph of the shoulder showing a proximal humerus fracture dislocation with disruption of the medial hinge. Illustration A is a representation of the Hertel criteria.

Incorrect Answers:
Answer 2: Angulation > 30° of fracture components is one of the Hertel criteria and a predictor of humeral head ischemia, not angulation < 30°.
Answer 3: Displacement of parts > 1cm is a predictor of humeral head ischemia.
Answer 4: An intact medial hinge is favorable and is not a predictor of humeral head ischemia.
Answer 5: A separate greater tuberosity fragment is expected in a four-part fracture and is not an independent predictor of humeral head ischemia or AVN.