Rotator Cuff Tendon Dimensional Variability, Novel Patient-Specific Measurement Method-Morphological Measurement for Rotator Cuff Tendon.

Introduction: The shoulder rotator cuff (RC) is crucial to shoulder function and involvement in shoulder pathology. RC tears have been extensively studied, and several classifications have been devised to quantify their magnitude. Various RC measurement techniques were introduced previously, utilizing cadaveric specimens, X-rays, CT scans, and MRI with different results published regarding humeral heads' different plane diameters and the correlation to age, gender, and height. There are very few studies measuring RC length in the general population.

Purpose: We aimed to assess the geometrical relation between rotator cuff tendon length and humeral head sagittal and axial diameters.

Methods: A total of 100 shoulder MRI scans of labral tear-suspected patients were reviewed, and the geometrical parameters of the rotator cuff length and proximal humerus sagittal and axial diameters were measured.

Results: The healthy population has wide variability in humeral diameter and rotator cuff length. We found a high correlation between humeral head sagittal and axial plane diameters and the rotator cuff tendon dimension. The orthogonal plane diameters disagree with the humeral head being round but rather spheric. The rotator cuff length changes according to the patient's gender and height.

Conclusion: This is a novel method for rotator cuff measurement, description, and classification according to the percentage of tear instead of length (cm). This method is more clinically oriented and relevant than most other previous methods.