Contribution and relationship of middle deltoid ultrasound biomarkers on functionality and return to play in shoulder instability patients.

Purpose To develop a description of middle deltoid ultrasound biomarkers in glenohumeral instability patients, and to determine their contributions to functional performance. Methods This cross-sectional study enrolled adults with glenohumeral instability. The ultrasound assessed muscle, fat, and fascia contrast, textural correlation, energy, homogeneity, entropy, ecointensity, histogram, and thickness. Moreover, the Western Ontario Shoulder Instability Index (WOSI), the Quick-Piper Fatigue scale-revised (Quick-Piper), the Questionnaire on the Self-Perception of the Athlete for Return to Standardized Training after Injury (RTP), a goniometer, and a dynamometer were used. Results Ninety-four patients were recruited. In women, muscle contrast was directly correlated with Quick-Piper (R = 0.47), while RTP and external rotation were inversely correlated (R = -0.43 to -0.40). Moreover, energy was inversely correlated with age (R = -0.58) and with BMI (R = -0.44). However, homogeneity was inversely correlated with age, WOSI, and Quick-Piper (R = -0.50 to -0.38), and directly correlated with RTP, force, abduction, and external rotation (R = 0.41 to 0.48). Furthermore, the histogram was directly correlated with Quick-Piper (R = 0.48) and inversely correlated with RTP (R = -0.45). Finally, muscle thickness showed a direct correlation with WOSI and Quick-Piper (R = 0.38 to 0.49), and an inverse correlation with RTP and external rotation (R = -0.48 to -0.47). Additionally, regression models were able to explain 54.7% of the WOSI, 47.7% of the Quick-Piper, and 50.2% of the RTP. Conclusion Architecture muscle biomarkers of the middle deltoid stratified by sex explained functionality and return to play, especially in women.