Archives of Orthopaedic and Trauma Surgery - 2026-03-28 - Journal Article
Prevalence and risk factors for stem subsidence following reverse shoulder arthroplasty using on-lay press-fit short stems.
Nishiura R, Nakazawa K, Manaka T, Hirakawa Y, Ito Y, Terai H
Topics
Key Takeaway
Stem subsidence (≥5 mm) occurred in 13.2% of RSA press-fit short stems, with metaphyseal filling ratio <70% (OR 0.90) and osteoporosis (OR 3.2) as independent predictors.
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Summary
This retrospective study evaluated prevalence and risk factors for stem subsidence in 151 patients undergoing RSA with on-lay press-fit short stems between 2017 and 2023, defining subsidence as ≥5 mm displacement on serial AP radiographs. Subsidence occurred in 20 patients (13.2%); logistic regression identified low metaphyseal filling ratio (FRmet <70%, OR 0.90) and osteoporosis (OR 3.2) as independent predictors. Despite radiographic subsidence, no significant difference in Constant score or ASES score was observed between subsidence and non-subsidence groups at final follow-up.
Key Limitation
Subsidence did not correlate with clinical outcome deterioration, raising uncertainty about whether the 5 mm radiographic threshold is clinically meaningful or represents a surrogate endpoint without functional consequence.
Original Abstract
INTRODUCTION
In reverse shoulder arthroplasty (RSA), press-fit short stems offer benefits such as reduced operative time and bone preservation. However, stem subsidence has been reported, although the risk factors remain unclear. This study aimed to determine the prevalence and risk factors for stem subsidence in RSA with on-lay press-fit short stems, hypothesizing that a lower filling ratio (FR) would correlate with subsidence.
MATERIALS AND METHODS
This retrospective analysis included patients who underwent RSA using on-lay press-fit short stems between 2017 and 2023, with a minimum follow-up of 2 years. Subsidence was defined as a ≥ 5 mm reduction in the distance from the tip of the greater tuberosity to the distal end of the stem on anteroposterior radiographs between the immediate postoperative and final follow-up evaluations. FR was assessed at the metaphyseal (FRmet) and diaphyseal (FRdia) levels. Neutral alignment was defined as a stem-shaft angle within 5°. Clinical outcomes included range of motion, Constant score, and American Shoulder and Elbow Surgeons score.
RESULTS
This study enrolled 151 patients: 65 with cuff tear arthropathy, 54 with massive rotator cuff tears, 29 with glenohumeral osteoarthritis, and three with shoulder dislocations. Osteoporosis was identified in 37 patients. Subsidence occurred in 20 patients (13.2%). The mean FRmet was significantly lower in the subsidence ≥ 5 mm group (67.7% ± 6.2) than the < 5 mm group (71.5% ± 8.0, p = 0.01). Logistic regression identified low FRmet (OR: 0.90, 95% CI: 0.82-0.99, p = 0.03) and osteoporosis (OR: 3.2, 95% CI: 1.05-9.96, p = 0.04) as significant risk factors. There was no significant difference in clinical outcomes with subsidence.
CONCLUSIONS
Subsidence occurred in 13.2% of patients following RSA with press-fit short stems. A lower FRmet (< 70%) and osteoporosis were significant predictors of subsidence. Achieving an FRmet ≥ 70% may reduce this risk, while cemented stems could be preferable for patients with osteoporosis.
LEVEL OF EVIDENCE
Level III; Retrospective study; Retrospective comparative study; Diagnostic Studies.