Sonoelastography to Predict Rotator Cuff Tears

This diagnostic test would be executed by a physician who has experiences of using Siemens Acuson S2000 ultrasound system for more than three year. The examination includes two of four rotator cuff muscles, listed as follows, supraspinatus muscle and infraspinatus muscle. Linear transducer (4-9 MHz) would be used for the whole test. The probe would be positioned along the longitudinal axis of the muscle belly.

Compressive sonoelastography technique is used for semiquantitative analysis. In order to maintain the quality of images, quality factor needs to be over or equal to 60. The quantitative analysis was performed by shear wave sonoelastography. While assessing, the region of interest (ROI) would be divided into four quadrants. The physicians will measure the shear wave velocity for wight times at the center point of each quadrant.

Passive range of motions of internal and external rotation, abduction, extension, and flexion, which are assessed by a goniometer.

Muscle strength assessment include the following motions, which are internal and external rotation, abduction, extension, and flexion. They are measured by a manual dynamometer.

Shoulder function that are scaled by using American Shoulder and Elbow Surgeons score.

MRI was performed on a 1.5T system (Signa Horizon LX, GE Healthcare) equipped with a standard shoulder surface coil. The shoulder MRI protocol was identical for all patients and consisted of axial proton-density-weighted fast spin-echo with fat suppression sequence, the sequences was performed above the level o f the acromioclavicular joint down to below the axillary pouch with the following parameters: Coronal oblique proton-density-weighted with and without fat suppression, with axis parallel to the supraspinatus tendon, and sagittal oblique proton-density--weighted with and without fat suppression, with axis perpendicular to the coronal oblique axis, the ast spin-echo sequences were performed with the following parameters: TR msec/TE msec, 2700-4800 /25-40, echo-train length, 6; matrix, 256 × 256; field of view, 180 mm; section thickness, 2.5 mm with 2-mm gap. No IV or intraarticular gadolinium was administered.

The investigator will discuss the surgical outcome with the orthopedist to define whether the tear side is repaired partially or completely. If the tendon can be repaired using simple side-to-side tendon repair, horizontal mattress transosseous repair via the bone trough and reduced into an anatomic position, or via the rough area of greater tuberosity (marginal converging repair), it is defined as complete repair of the tendon. If the tendon cannot be reduced to the anatomic footprint and the orthopedist only secures re-attachment of the infraspinatus to the posterior side of greater tuberosity and/or the subscapularis of lesser tuberosity, it is defined as partial repair of the tendon.

The ultrasound machine will be calibrated similarly using the musculoskeletal (MSK) preset and B-mode with autogain. The dynamic range will be set at 70 dB for all participants. The examiners will apply adequate transducer pressure to obtain optimal images for comparisons of muscle and bone echo. The Heckmatt scale will be used to grade the muscle echogenicity within each ROI of supraspinatus and infraspinatus muscles. The grading rule is as follows:

• Grade 1: Normal
• Grade 2: Increased muscle echo intensity with distinct bone echo
• Grade 3: Marked increased muscle echo with reduced bone echo
• Grade 4: Very strong muscle echo and complete loss of bone echo