Prognostic factors and limitations of anatomic shoulder arthroplasty for the treatment of posttraumatic cephalic collapse or necrosis (type-1 proximal humeral fracture sequelae)

Abstract

Background: The aim of this study was to evaluate the prognostic factors and limitations of anatomic unconstrained shoulder arthroplasty, performed without tuberosity osteotomy, for the treatment of secondary glenohumeral arthritis following posttraumatic cephalic collapse or necrosis of the humeral head, defined as type-1 fracture sequelae.

Methods: Fifty-five patients with type-1 fracture sequelae treated with anatomic shoulder arthroplasty were included in this retrospective single-center cohort study. All anatomic humeral prostheses were implanted without performing a greater tuberosity osteotomy. Glenoid resurfacing was performed in forty-four patients (80%). Clinical and radiographic analysis was performed at a mean of fifty-two months (range, twenty-four to 180 months) postoperatively.

Results: Four reoperations (7%) were performed, including two revisions in patients who required glenoid resurfacing because of glenoid erosion after hemiarthroplasty. At the time of the latest follow-up, 93% of patients were satisfied or very satisfied, and the mean Subjective Shoulder Value (SSV) was 81%. There were significant improvements in the mean Constant score (from 32 to 69 points), active anterior elevation (from 88° to 141°), external rotation (from 6° to 34°), and internal rotation (from the buttock to L3). Significantly poorer results were associated with proximal humeral deformity in varus and with fatty infiltration of the rotator cuff muscles. Patients with proximal humeral deformity, specifically varus or valgus malunion of the greater tuberosity, had a mean Constant score that was 10 points lower and active elevation that was almost 20° less than patients with no such deformity. The poorest results were observed in patients with varus malunion.

Conclusions: Our study confirmed that the outcomes of anatomic shoulder arthroplasty for the treatment of type-1 fracture sequelae are good and predictable when deformation of the proximal humerus is acceptable(i.e., when no greater tuberosity osteotomy is necessary). The results were negatively affected by proximal humeral varus deformity and by fatty infiltration of the rotator cuff on imaging studies. In such cases, reverse shoulder arthroplasty may be more appropriate, especially in elderly patients.