Surgeons Can Take Steps to Minimize Risk of Tuberosity Absorption After ORIF of Proximal Humerus Fractures

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After humeral open reduction and internal fixation (ORIF), bone resorption of the greater tuberosity occurs in an estimated 3%–10% of cases. Non-anatomical healing of the greater tuberosity is thought to lead to rotator cuff dysfunction and inferior functional outcomes.

In a retrospective comparative study, Satoshi Miyamura, MD, PhD, postdoc, and Neal C. Chen, MD, chief of the Hand & Arm Center of the Department of Orthopaedic Surgery at Massachusetts General Hospital, and colleagues determined risk factors for bone reduction of the greater tuberosity after ORIF. Their report appears in the Journal of Shoulder and Elbow Surgery.

Study Methods

The data used in this study came from 136 patients who had Neer three-part or four-part proximal humerus fractures treated with ORIF at one of five hospitals between January 1, 2000, and December 31, 2015. All fractures involved the greater tuberosity, and all patients were followed for at least 24 weeks. Radiographs and CT images were reviewed by four orthopedic surgeons who had not been involved in the care of these patients.

Incidence of Resorption

The average length of follow-up was 22.7 months. 30 patients (22%) developed bone resorption of the greater tuberosity (average time to development, 26 weeks).

Intraoperative Risk Factors

In multivariable analysis, intraoperative factors independently associated with greater risk of tuberosity resorption were:

• An unreduced greater tuberosity (Odds Ratio, 10.9; P < 0.001)
• Inadequate medial support (Odds Ratio, 15.0; P < 0.001)
• Intramedullary fibular strut reconstruction (Odds Ratio, 4.5; P = 0.02)

When a fibular cortical strut graft is inserted into the metaphysis, it may disrupt a substantial amount of the endosteal blood supply. It is possible that strut grafts can result in tuberosity resorption by interfering with revascularization.

Fragment-specific Risk Factors

The researchers used propensity scores to match 15 patients from the resorption group with 15 patients from the non-resorption group. They fed CT data into bone simulator software to construct a three-dimensional model of each patient's shoulder joint.

The bone resorption group was significantly more likely than the non-resorption group to have:

• A larger number of fragments
• Smaller fragments
• Fragments with lower bone density

The size of the greater tuberosity fragment was particularly prognostic. If its volume was smaller than about 15% of the volume of the humeral head, the likelihood of resorption was high, with a sensitivity of 87% and a specificity of 93%.

Clinical Pearls

• Greater tuberosity fragments smaller than 15% of the humeral head are at risk of resorption, especially in the presence of underlying conditions that can affect bone density
• To minimize the risk of tuberosity resorption, reduce the greater tuberosity and provide adequate medial support at the calcar
• Use of a fibular strut graft should be made cautiously when patients are at higher risk of greater tuberosity resorption
• In older patients with lower bone density for whom reverse shoulder arthroplasty is an option, consider greater tuberosity fragment size when choosing between ORIF and reverse shoulder arthroplasty

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