Macro- and Micro-Morphological Properties of the Rotator Cuff Structures in the Chronic Stage of Tendinopathy in Para Swimmers

<b>Background/Objectives</b>: This study aimed to characterize macro- and micro-morphological properties of the supraspinatus tendon (SST) in para swimmers during the chronic stage of rotator cuff tendinopathy, integrating ultrasound assessments of tendon thickness, peak spatial frequency radius (PSFR) for collagen organization, acromiohumeral distance (AHD), and occupation ratio to evaluate subacromial impingement risk. <b>Methods</b>: In a cross-sectional design, 43 elite para swimmers (aged 18-30 years, S7-S10 classes with lower extremity impairments) from Para Swimming Team Poland were divided into rotator cuff tendinopathy (RC; n = 22) and asymptomatic control (CON; n = 21) groups. Measurements on the dominant shoulder utilized B-mode ultrasound (Alpinion X-CUBE 90) to assess SST thickness at 5, 10, and 15 mm proximal to the greater tuberosity, PSFR via MATLAB-analyzed spatial frequency spectra, AHD, and occupation ratio. Two-way and one-way ANOVAs assessed group and measurement effects (<i>p</i> < 0.05); Pearson correlations examined the relationships between thickness and PSFR. <b>Results</b>: Para swimmers with tendinopathy exhibited greater SST thickness across sites (<i>p</i> < 0.001, η² = 0.63), higher PSFR at all intervals (<i>p</i> ≤ 0.009, η² = 0.53) peaking at 10 mm, wider AHD (<i>p</i> = 0.002, η² = 0.21), and lower occupation ratio (<i>p</i> < 0.001, η² = 0.44) versus controls. Strong positive correlations linked thickness and PSFR proximally (r = 0.75-0.79, <i>p</i> < 0.001). <b>Conclusions</b>: Chronic tendinopathy in para swimmers manifests as thickened SST with collagen disarray, altered subacromial space, and impingement risk, distinguishing pathological from healthy tendons. Integrated ultrasound metrics aid diagnosis and inform interventions for overhead athletes with locomotor disorders.