JSES - 2026-03-17 - Journal Article; Review
Biomechanical Changes After Reverse Total Shoulder Arthroplasty: A Systematic Review of Advanced Measurement Technologies.
Thomson A, Felix T, Lichtwark G, Whitehouse S, Gupta A, Kerr G
Topics
Key Takeaway
rTSA restores forward elevation primarily through compensatory scapulothoracic upward rotation rather than glenohumeral mechanics, with glenohumeral contribution, axial rotation, and scapulohumeral rhythm remaining reduced versus contralateral or healthy controls across all 24 included studies.
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Summary
This systematic review of 24 Level III studies (1985–2025) used motion capture, EMG, IMU, and accelerometry data to characterize biomechanical adaptations after rTSA. Forward elevation improved consistently, but was achieved via increased scapulothoracic upward rotation, retraction, and posterior tilt rather than restored glenohumeral kinematics. Wearable sensors confirmed increased arm use and interlimb symmetry postoperatively, though time above shoulder height remained limited, and EMG showed deltoid and upper-trapezius dominance with minimal posterior cuff recruitment.
Key Limitation
Implant design heterogeneity (lateralization, inclination, offset) across included studies prevents any conclusions about how specific construct parameters influence the observed compensatory biomechanical patterns.
Original Abstract
BACKGROUND
Reverse total shoulder arthroplasty (rTSA) consistently improves pain and function; however, the biomechanical mechanisms underpinning postoperative function and joint-level adaptations remain incompletely defined. Advanced measurement tools, including motion capture, electromyography (EMG), inertial measurement units (IMU), and accelerometry, enable objective assessment of joint motion, muscle activation, and real-world arm use. This systematic review synthesizes evidence from studies using advanced biomechanical methods to evaluate postoperative kinematics, upper-limb activity, and muscle activation after rTSA.
METHODS
Seven databases (1985-2025) were searched for observational studies reporting quantitative biomechanical outcomes after rTSA, compared with preoperative baselines, contralateral shoulders, or healthy controls. Outcomes were categorized as kinematics, real-world upper-limb activity, or neuromuscular activation. Methodological quality was assessed using Joanna Briggs Institute criteria, and levels of evidence were classified according to Journal of Shoulder and Elbow Surgery guidelines.
RESULTS
Twenty-four studies (10 cohort and 14 case-control; all Level III) met inclusion criteria. Twenty-one had moderate risk-of-bias and three high risk. Implant designs, surgical indications, and follow-up durations were heterogeneous. High-rigor optical and electromagnetic motion capture studies showed consistent gains in forward elevation, while glenohumeral contribution, axial rotation, and scapulohumeral rhythm remained reduced relative to contralateral or healthy shoulders. Elevation occurred predominantly through increased scapulothoracic upward rotation, retraction, and posterior tilt. Laboratory-based IMU studies showed similar patterns of greater scapular contribution despite non-standardized coordinate systems. Wearable sensors reported increased postoperative arm use and improved interlimb symmetry, although time spent above shoulder height remained limited. EMG studies demonstrated increased deltoid and upper-trapezius activation with limited posterior cuff recruitment.
CONCLUSION
rTSA restores forward elevation primarily via compensatory scapulothoracic motion and deltoid-driven neuromuscular strategies rather than normalization of glenohumeral mechanics. Standardized, longitudinal studies integrating high-fidelity kinematics, EMG, and real-world activity monitoring, with explicit reporting of implant construct parameters, are needed to clarify how surgical technique and implant design influence postoperative biomechanics and functional recovery.