A propensity matched cohort analysis: Cemented vs press fit humeral stem fixation in anatomic total shoulder arthroplasty

Abstract

Introduction

Historically, humeral stems were cemented for anatomic shoulder arthroplasty (aTSA). However, cementless, or press-fit, fixation has been increasingly used. This study aims to compare outcomes and revision rates between cemented and press-fit humeral stems.

Methods

Institutional records were searched to identify all patients who underwent aTSA with cemented humeral fixation or press-fit fixation between 2009 and 2021. A 3:1 propensity match based on age, sex, pre-op forward elevation and external rotation was conducted. Mean functional measurements were compared using a 2-Sample t-Test, ordinal variables via Wilcoxon-Mann Whitney test, and categorical variables via the Chi-squared test.

Results

There were 35 cemented humeral fixation shoulders matched with 105 humeral press-fit shoulders included in the final cohort. Both groups had similar characteristics at baseline regarding age, sex, body mass index, Charlson Comorbidity Index, mean follow-up, ROM, and strength measurements. Average age at surgery was 61.88 ± 6.68 years with an average follow-up time of 5.61 ± 2.86 years. Post-operatively, press-fit fixation demonstrated significant improvement in all ROM testing: external rotation (ER), forward elevation (FE), internal rotation (IR)-and all strength testing: ER, FE, and IR. Cement fixation demonstrated significant improvement in all ROM testing but only in FE strength testing. Inter-group post-op ROM and strength testing comparisons revealed superior external rotation (p = 0.007) and forward elevation (p = 0.047) ROM in the press-fit group with similar internal rotation ROM values and similar strength testing. There were higher revision rates in the cement fixation cohort (Cement: 11.4 % vs press-fit: 3.8 %; p = 0.036).

Conclusion

The results of this analysis showcase that press-fit fixation is a viable option for aTSA. Press-fit fixation shoulders had better ROM in terms of external rotation and forward elevation as well a better survival time to revision compared to cement fixation.