Kaneko, Kazuo

Purpose To determine the feasibility of shear wave elastography (SWE) with B‐mode ultrasound in predicting the stiffness of the rotator cuff muscle before arthroscopic rotator cuff repair to evaluate the difficulty of the surgical procedure, as well as to compare SWE with the Goutallier stage on magnetic resonance imaging (MRI). Methods Thirty‐eight patients with a full‐thickness supraspinatus tear requiring arthroscopic rotator cuff repair participated. The Goutallier stage of fatty infiltration on MRI was measured before surgery, as was the SWE modulus of the anterior superficial, anterior deep, posterior superficial, and posterior deep (PD) regions of the supraspinatus muscle. To measure the stiffness of the supraspinatus musculotendinous unit during surgery, the supraspinatus tendon was axially stretched until the anatomic insertion site was reached, and force per deformation was recorded. The correlation between stiffness of the supraspinatus and SWE value in each region of the supraspinatus muscle or Goutallier stage was determined. In addition, patients were divided into 2 groups: (1) In the complete footprint coverage group, greater than 50% of the footprint was covered during the stiffness measurement, and (2) in the incomplete footprint coverage group, less than 50% of the footprint was covered during the stiffness measurement. Differences in SWE value and Goutallier stage were measured between the 2 groups. Results The best correlation of stiffness with the SWE modulus of the PD muscle of the supraspinatus was R = 0.69, and the correlation of stiffness with the Goutallier stage on MRI was R = 0.48. The SWE value of the PD region was greater in the incomplete footprint coverage group than in the complete footprint coverage group, although the Goutallier stage was not significantly different. Conclusions The highest correlation with stiffness of the supraspinatus musculotendinous unit was with the SWE modulus of the PD muscle, as compared with SWE evaluation of the other regions or the Goutallier stage on MRI. Ultrasound SWE can predict the stiffness of the supraspinatus musculotendinous unit best. Clinical Relevance Rotator cuff retraction adds difficulty to arthroscopic rotator cuff repair. Ultrasound SWE may be used for presurgical planning.