The role of eccentric and offset humeral head variations in total shoulder arthroplasty.

BACKGROUND

Humeral head variations were developed based on anatomic and biomechanical advantages; however, the effect of this expanded prosthetic inventory has yet to be investigated clinically. This study seeks to determine whether prosthetic variety has led to better outcomes, has led to similar outcomes facilitating joint reconstruction, or created any unanticipated complications.

METHODS

One hundred sixty primary total shoulder arthroplasties were performed for osteoarthritis. Patients received 52 standard, 60 eccentric, and 48 offset humeral heads. Head geometry was selected intraoperatively during trialing based on a complementing relationship to the glenoid throughout a near-normal range of motion. Patients had 2 years of follow-up or follow-up until reoperation (mean, 4.7 years; range, 0.8-8.3 years).

RESULTS

Mean pain scores decreased from 4.5 to 1.9 on a 5-point scale (P < .001), mean elevation increased from 94° to 150°, mean external rotation increased from 22° to 57° (P < .001), larger lucent lines (≥ 1.5 mm) or change in glenoid position occurred around 19 components, and survivorship was 98% (95% confidence interval, 97%-100%) at 1 year and 98% (95% confidence interval, 95%-100%) at 5 years. No difference among head configurations was found for any of these outcomes.

CONCLUSIONS

Evolution of designs has provided options to more accurately re-create anatomy including changes caused by osteoarthritis. At the length of follow-up in this study, clinical outcomes, radiographic performance, and survivorship are equivalent when applying these humeral head variations, and no special complications have developed.