Medial calcar bone resorption after anatomic total shoulder arthroplasty: does it affect outcomes?

The incidence of medial calcar resorption has been shown to be common after uncemented total shoulder arthroplasty (TSA). With etiologies including stress shielding, debris-induced osteolysis, and infection, the clinical impact of medial calcar resorption has not been specifically examined. The purpose of this study was to determine whether resorption is associated with inferior outcomes or higher rates of radiographic loosening in TSA patients.

We conducted a retrospective review of TSA patients with minimum 2-year clinical follow-up. Patient-reported and functional outcome measures were recorded preoperatively and postoperatively. Postoperative radiographs were evaluated for glenoid and humeral component loosening. A new calcar resorption grading system was introduced to quantify the degree of resorption and assess the progression.

A total of 171 patients met the inclusion criteria, with average clinical and radiographic follow-up periods of 50 and 46 months, respectively. Calcar resorption was identified in 110 patients (64.3%). No significant overall differences were observed between the patients with and without calcar resorption. Subgroup analysis showed that patients with grade 3 resorption had a higher incidence of glenoid radiolucencies (50%, P = .001) and patients with a progression from grade 1 to grade 3 had higher incidences of glenoid (50%, P = .003) and humeral (9%, P = .039) radiolucencies.

Medial calcar resorption following TSA with a standard-length press-fit humeral component is common. Overall, no differences in patient-reported outcome measures or radiographic loosening were found compared with patients without calcar resorption. However, grade 3 calcar resorption and more dramatic progression of resorption should raise the suspicion of prosthetic loosening.