Comparing clinical and functional outcomes following anatomic total shoulder arthroplasty based on humeral component length (Equinoxe; Exactech, Inc.).

BACKGROUND

There has been a trend toward the use of shorter humeral components with the goal of preserving bone, decreasing operative time, and a theoretical decrease in stress shielding. The purpose of this study was to compare the clinical and functional outcomes of anatomic total shoulder arthroplasty among standard-length stem, short-stem, and stemless humeral components, with a minimum of 2-year follow-up.

METHODS

A retrospective review of a multicenter international database was performed for anatomic total shoulder arthroplasty with a minimum of 2-year follow-up between 2018 and 2021 using Standard Equinoxe stems, Equinoxe Preserve (Short) stems, or Equinoxe Stemless components (Exactech, Inc., Gainesville, FL, USA). Outcome measures included range of motion and patient-reported outcome measures (PROMs). Postoperative radiographic findings including the presence of glenoid and humeral radiolucent lines in zones specific to the stem design were evaluated. Complication and revision rates were recorded.

RESULTS

A total of 825 patients were included (164 standard-length stem, 356 short-stem, and 305 stemless). The mean follow-up was 37.9 ± 12.6 months. There was no significant difference in previous shoulder surgeries or medical comorbidities among the groups. The mean final forward elevation for standard-length stem, short-stem, and stemless components was 156°, 158°, and 156°, respectively (P = .636). Final external rotation for standard-length stem, short-stem, and stemless components was 58°, 57°, and 51°, respectively (P < .001). Final internal rotation scores were similar across groups (P = .090). Final PROMs did not meet the minimal clinically important difference across cohorts. The mean operative time for the standard-length stem group was 101.8 minutes, for the short-stem group 92.7 minutes, and for the stemless group 89.2 minutes (P < .001). There was no statistically significant difference in complication rate or revision rate. The rate of humeral component radiolucent lines was greater for standard-length stems (P < .001) with a rate of 11.9% for standard-length stem, 1.7% for short-stem, and 1.6% for stemless components. Patient satisfaction was also similar among the 3 cohorts (P = .757).

CONCLUSIONS

Our findings demonstrate similar postoperative motion and PROM scores irrespective of the humeral stem component used. Complication and revision rates were similar for all 3 cohorts. Radiolucent lines were lowest with the stemless component. Early data support the use of stemless and short-stem humeral components that may be advantageous in decreasing operative time and preserving humeral bone for potential revision. Longer term studies are needed to confirm the survivability and durability of these shorter components.