Humeral component modularity may not be an important factor in the outcome of shoulder arthroplasty for glenohumeral osteoarthritis.

We examined the outcomes of using 3 types of humeral prostheses in total shoulder arthroplasty for osteoarthritis: a modular prosthesis with variable head diameters (MV), a nonmodular prosthesis with variable head diameters (NV), and a nonmodular prosthesis with a fixed head diameter (NF). Patients (N=101) completed self-assessments of shoulder function and health status before surgery and at follow-up between 30 and 60 months after surgery. Outcomes for the MV and NV prostheses did not differ statistically. The NF prosthesis trended toward poorer functional scores. Two Short Form-36 dimensions were statistically significantly lower (P<.05) in the NF group than in the MV and NV groups. These results fail to confirm that humeral component modularity is an important factor in the outcome of shoulder arthroplasty.