JSES - 2026-05-01 - Journal Article
Risk of humeral implant subsidence in Easytech stemless rTSA is mainly associated with surgical technique and patient activity.
Azar M, Nourissat G, Antoni M
Topics
Key Takeaway
Humeral implant subsidence occurred in 25% of stemless rTSA cases at mean 43 months, driven by varus cut angle <140°, non-parallel implant seating, and superior glenosphere positioning, yet subsidence did not correlate with worse Constant scores or revision rates.
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Summary
This single-center retrospective study evaluated risk factors for humeral component subsidence in 72 consecutive stemless rTSA cases using serial radiographic comparison at minimum 2-year follow-up. Subsidence occurred in 25% of shoulders (12.5% mild, 12.5% significant), with 94% occurring in varus; independent associations included humeral cut angle <140°, non-parallel implant seating, superior glenosphere positioning, male sex, and greater height. Despite the 25% subsidence rate, there was no significant difference in overall Constant score, complication rate, loosening, or revision surgery between subsided and non-subsided implants.
Key Limitation
The 43-month mean follow-up is insufficient to determine whether currently asymptomatic subsidence progresses to loosening, periprosthetic fracture, or functional decline over a decade-level horizon.
Original Abstract
BACKGROUND
Stemless reverse shoulder arthroplasty (rTSA) has been used in Europe for over 15 years with promising clinical outcomes and low complication rates. However, concerns persist regarding humeral component subsidence due to the metaphyseal fixation. Limited data exist on this potential complication. The primary aim of this study was to identify factors associated with humeral implant subsidence in stemless rTSA. The secondary objective was to evaluate the functional impact of such subsidence.
METHODS
This retrospective, single-center study included a consecutive series of patients who underwent primary stemless rTSA for indications including primary osteoarthritis, cuff tear arthropathy, post-traumatic arthritis, or massive irreparable rotator cuff tears. All patients had a minimum 2-year follow-up with clinical (Constant score and simple shoulder value) and radiographic evaluation. Implant subsidence was assessed by comparing immediate postoperative and final follow-up X-rays and categorized as none, mild (<5°), or significant (>5°). Radiographs were reviewed independently by 2 observers. Associations between subsidence and demographic, surgical, and implant positioning factors were analyzed, along with clinical outcomes and complication rates.
RESULTS
Seventy-two shoulders were analyzed (48.6% male; mean age 66.9 ± 8.7 years; mean follow-up 43.3 ± 9.0 months). Mild and significant humeral subsidence were observed in 12.5% (9/72) of cases each. In 94% (17/18), subsidence occurred in varus. Univariate analysis identified several factors significantly associated with humeral component subsidence: male gender (P = .006), greater patient height (P = .007), lower preoperative external rotation (P = .036), a humeral cut angle <140° (P = .009), nonparallel implant alignment relative to the humeral cut (P = .014), and superior positioning of the glenosphere (P < .001). Subsidence was associated with greater strength (P = .017), higher subjective shoulder value (P = .025), and higher activity scores (P = .022) at the last follow-up. There was no significant association between subsidence and overall Constant score (P = .097), patient satisfaction (P = .327), implant loosening (P = .26), occurrence of complications (P = .17), or revision surgery (P = .45).
CONCLUSION
At a mean follow-up of 43 months, humeral implant subsidence was observed in 25% of cases, predominantly in varus. Subsidence was linked to implant positioning and patient activity level but was not associated with poorer clinical outcomes. These findings support the importance of optimal surgical technique in stemless rTSA.