Evaluation of deltoid muscle quality in reverse shoulder arthroplasty: correlation of MRI findings with postoperative function and strength
摘要
To evaluate associations between MRI-derived deltoid muscle parameters (areal fatty infiltration [FI] and cross-sectional area [CSA]) and clinical outcomes one year after reverse total shoulder arthroplasty (RTSA).
Materials and methodsIn this prospective, cross-sectional study, RTSA patients underwent 1.5-T MRI one year after surgery. Deltoid areal FI (%) and CSA (normalized to height, [CSAnorm, mm²/m]) were quantified in anterior, lateral, and posterior parts on T2-weighted imaging with metal artifact reduction. Spearman’s correlation coefficients and age- and sex-adjusted linear regression models assessed associations with clinical outcomes (Constant-Murley Score [CMS] and isometric strength [N]).
ResultsAmong 25 patients (75 years [IQR 70–79], 72% females, BMI 28.7 kg/m² [IQR 24.6–29.4]) whole deltoid CSAnorm was positively correlated with CMS (r = 0.51, p = 0.010) and abduction strength (r = 0.48, p = 0.015), while FI showed negative correlations (r = −0.46 to 0.60, p = 0.002–0.019). Anterior CSAnorm positively correlated with CMS (r = 0.55, p = 0.005) and strength (r = 0.41 to −0.42, p = 0.034-0.040), while anterior FI showed negative correlations with CMS (r = −0.79, p < 0.001) and strength (r = −0.58 to −0.63, p = 0.002–0.003). Lateral CSAnorm correlated with CMS (r = 0.49, p = 0.014) but not with strength, while lateral FI showed no significant correlations. After adjustment, higher anterior CSAnorm was associated with better function and strength (β = 0.84–1.14, p = 0.003–0.028), and higher FI was associated with worse function and strength (β = −0.49 to −0.92, p < 0.001–0.014). Lateral CSAnorm remained associated with CMS (β = 0.40, p = 0.034), while lateral FI showed no significant associations.
ConclusionsMetal artifact-reduced MRI-derived FI and CSAnorm are associated with shoulder function and strength one year after RTSA, potentially serving as objective markers for postoperative assessment.
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