How does subscapularis repair affect joint loads? Effect of humeral tray thickness in Reverse Total Shoulder Arthroplasty (rTSA)
Bibliographic record
Abstract
Background This study aimed to evaluate how subscapularis tendon repair influences joint loads in relation to humeral offset and arm position. Patients and methods Two fresh-frozen, whole-body cadaveric shoulders underwent a reverse total shoulder arthroplasty (rTSA) on the humeral side using an internal proprietary load-sensing system (LSS) (Goldilocks, Statera Medical, Montreal, Canada). In addition to three "complex" Activity Daily Life positions ("behind the back", "overhead reach", and "across the chest"), four standard postures (external rotation, extension, abduction, and flexion) were used to record the glenohumeral loads (Newtons) and their locations applied to the implant. The humeral system's adjustability function was used to gradually raise the thickness for each setting from 0 to 6 mm. The first part of the tests consisted of taking these measurements with the repaired subscapularis tendon. Once all the measurements had been taken, the tendon was detached, and the same measurements were repeated in the same order. Load and contact point were measured using the load centroid radial distance (|r|). Results The measurements showed good repeatability with an intra-class correlation coefficient (ICC) greater than 0.9 for all positions. Increasing the thickness of the humeral implant from 0 to 6 mm, without subscapularis, resulted in a refocusing of loads on the humeral cup for several positions, except for abduction at 60 ° (|r| 0mm = 1 mm VS |r| 6mm = 0.9 mm; p = 0.570), cross body (|r| 0mm = 0.7 mm VS |r| 6mm = 0.5 mm; p = 0.413) and overhead reach (|r| 0mm = 1 mm VS |r| 6mm = 0.9 mm; p = 0.284). Subscapularis repair enhances this recentering effect for all positions, with a particularly significant influence on abduction at 60 °, "behind back" and "overhead reach" (|r| 6mm = 0.2 mm VS 0.9 mm, p < 0.001). Subscapularis repair also significantly increased joint loads for these positions at 6 mm humeral lateralization. Discussion The findings of this biomechanical study provide substantial evidence to support the hypothesis that the subscapularis muscle plays a pivotal role in the process of refocusing joint loads in rTSA. Consequently, subscapularis repair may exert a biomechanical effect on rTSA stabilisation. Level of evidence V; Biomechanical study.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.006 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.002 | 0.001 |
| Bibliometrics | 0.002 | 0.002 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.002 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".