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Position of Greater Tuberosity Important After Shoulder Fracture

Fracture of the upper portion of the humerus (upper arm) bone can lead to serious problems. If the bone breaks into several pieces, there may be a collapse of the head of the humerus.

Anytime the head of the humerus is distorted or the fracture fails to heal, avascular necrosis (AV) can occur. AV is the loss of blood supply to the humeral head. Without this lifeline, the bone starts to die.

In this report, 38 patients are studied who had a total shoulder arthroplasty (TSA) (replacement) and who later developed AV. The researchers were looking for ways to predict (and prevent) a poor outcome after TSA for this type of fracture.

They used X-rays before and after the TSA to measure the shape and position of the humeral tuberosities. Tuberosities are bumps on the bone where muscles and ligaments attach. The shoulder has two main tuberosities: the lesser tuberosity and the greater tuberosity.

The results of this study showed that greater tuberosity malunion is a negative predictor of outcomes. In other words, for those patients who had this deformity, the final results were worse than for patients with normal or near normal tuberosity alignment.

Motion and function were both impaired by malunion of breaks in the upper humerus. X-ray measurements of greater tuberosity position called greater tuberosity offset (GTO) and posterior offset (PO) can be used as reliable predictors of clinical results.

The surgeon can use this test to identify potential problems and plan accordingly. There are other factors to consider but GTO and PO do affect prognosis. Using this information, patients can be told what to expect after surgery.

References: Mark Tauber, MD, et al. Shoulder Arthroplasty for Traumatic Avascular Necrosis. In Clinical Orthopaedics and Related Research. December 2007. Number 465. Pp. 208-214.

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