Related Experiment Video
Updated: Oct 29, 2026
Decellularization-Based Quantification of Skeletal Muscle Fatty Infiltration
Published on: June 9, 2023
The Deltoid Fatty Degeneration Index (DFDI): a CT-based composite measure associated with functional outcome after
Giulia Rescigno1, Francesco Suraci2, Cristiano Benelli3
1Ospedale G.B. Grassi, Roma, Italy.
Purpose:
To develop a CT-based deltoid fatty degeneration index (DFDI) integrating deltoid muscle quality and quantity, to assess its association with 12-month functional outcomes after primary reverse total shoulder arthroplasty (RTSA), and to internally evaluate model performance.
Methods:
This retrospective single-center cohort included 100 primary RTSAs. Mean deltoid attenuation (HU) and cross-sectional area (CSA) were measured on a standardized preoperative CT slice. The DFDI was defined as 0.50 (-ZHU) + 0.50 (-ZCSA). Associations with Constant-Murley (CMS), ASES, and Oxford Shoulder Scores (OSS) were examined using Spearman correlations and multivariable linear regression. Internal validation used 2000 bootstrap resamples and repeated 10-fold cross-validation.
Results:
Mean age was 73.3±4.5 years; 68 patients were women. DFDI correlated with CMS (ρ = - 0.780), ASES (ρ = - 0.758), and OSS (ρ = - 0.754; all p < 0.001). In the adjusted model, DFDI remained associated with CMS (B = - 6.58, 95% CI - 9.23 to - 3.93; p < 0.001). Model R2 was 0.724 (adjusted R2 = 0.712), with bootstrap-corrected R2 = 0.695 and repeated cross-validated R2 = 0.679.
Conclusion:
A CT-based DFDI combining deltoid attenuation and cross-sectional area was associated with 12-month functional outcomes after primary RTSA. Internal validation suggested reasonably preserved model performance, although external validation and calibration are required before clinical implementation.