Rotator Cuff Fatty Infiltration and Atrophy Are Associated With Functional Outcomes in Anatomic Shoulder Arthroplasty
Bibliographic record
Abstract
BACKGROUND: Shoulder arthroplasty provides reliable pain relief and restoration of function. However, the effects of fatty infiltration and atrophy in the supraspinatus and infraspinatus muscles on functional outcomes are not well understood. QUESTIONS/PURPOSES: The purposes of this study were to (1) compare preoperative with postoperative fatty infiltration and atrophy of the supraspinatus and infraspinatus muscles after primary shoulder arthroplasty; and (2) identify any associations between these variables and outcome measures. METHODS: A retrospective analysis was undertaken of 62 patients with a mean age of 67 years (range, 34-90 years) who underwent shoulder arthroplasty. CT scans were conducted preoperatively and at 12 months postoperatively. Outcome variables included the degree of supraspinatus and infraspinatus fatty infiltration (percent fatty infiltration and Goutallier grade), muscle area (percent muscle area and Warner atrophy grade), shoulder strength, and the Western Ontario Osteoarthritis Score (WOOS), American Shoulder and Elbow Surgeons score, and Constant outcome score. RESULTS: Preoperatively, the mean percent fatty infiltration (FI) within the supraspinatus and infraspinatus was identical at 14%. One year after shoulder arthroplasty, both muscles had less fatty infiltration (6% and 7%, respectively; p<0.001). Similarly, the Goutallier grade significantly improved postoperatively for the supraspinatus (p=0.0037) and infraspinatus (p=0.0007). Conversely, measures of muscle atrophy remained unchanged postoperatively (p>0.251). Preoperatively, greater supraspinatus percent FI was negatively associated with preoperative shoulder strength (r=0.37, p=0.001) and Constant score (r=0.38, p=0.001). Postoperative infraspinatus percent FI was negatively associated with postoperative strength (r=0.3, p=0.021) and Constant score (r=0.3, p=0.04). Multivariable regression analysis of possible predictive factors demonstrated that preoperative supraspinatus percent muscle area (p=0.016) and the diagnosis of osteoarthritis (p=0.017) were associated with better followup WOOS scores, and preoperative supraspinatus strength was associated with postoperative strength (p=0.0024). Higher degrees of preoperative percent FI were not associated with worse patient-reported outcomes postoperatively. CONCLUSIONS: Supraspinatus and infraspinatus fatty infiltration improves after shoulder arthroplasty, whereas muscle area remains unchanged. Although further study of these variables is required, the negative associations identified between preoperative supraspinatus atrophy and the diagnosis of rheumatoid arthritis and postoperative quality-of-life outcome scores may aid the clinician in selecting the best treatment option for glenohumeral arthrosis and in the management of patient expectations. LEVEL OF EVIDENCE: Level III, prognostic study.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.004 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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 source (direct Gemma or distilled Codex), 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".