Uncemented humeral stems in reverse total shoulder arthroplasty: a systematic review

Background: The objective of this study is to understand the clinical and radiographic outcomes for uncemented humeral stems in reverse total shoulder arthroplasty. The usage of an uncemented stem is increasing in incidence, and it is important to understand both outcomes and complications for this stem. Methods: Studies were included if range of motion, radiographic outcomes, and complication outcomes in relation to uncemented humeral stems in reverse total shoulder arthroplasty were mentioned. Studies were excluded if they did not provide clinical data about uncemented stems, such as surgical technique manuscripts, case reports, and animal studies. PubMed, MEDLINE (Ovid, New York, NY, USA), Scopus (www.scopus.com), and Web of Science were queried using relevant search terms in January 2021. Paired t-tests were done to present and synthesize the results. Results: Twenty-six studies were included in this review. Four were of Level III evidence, and 22 were of Level IV evidence, totaling 1620 shoulders. Forward flexion improved from 67° ± 18° to 126° ± 15° (P <.001) and external rotation improved from 18° ± 8° to 36° ± 12° (P =.002). Constant scores increased from 28 ± 10 to 68 ± 14 (P <.001) and visual analog scale scores decreased from 7 ± 2 to 2 ± 2 (P <.001). Radiographic outcomes included scapular notching (n = 173), tuberosity union (n = 120), and radiolucent lines (n = 329). The most frequently observed complications in this systematic review included fracture (n = 52), infection (n = 24), and shoulder dislocation (n = 16). Discussion: Uncemented humeral stems show significant improvements in range of motion and patient-reported outcomes. Perioperative fractures and scapular notching continue to be prevalent in this population. Analysis of previous literature indicates that humeral loosening is comparative between cemented and uncemented humeral stems, but operative time is significantly reduced in uncemented stems. Limitations of this review include the paucity of Level III or higher literature, which makes it challenging to compare uncemented and cemented humeral stem outcomes.