Abstract: Objective To explore the application value of high-frequency ultrasound and elastography technology in following up the rehabilitation effect after supraspinatus tendon repair. 
Methods A total of 39 patients who underwent arthroscopic rotator cuff repair due to simple supraspinatus tendon tear in the Department of Shoulder and Elbow, the Third Hospital of Hebei Medical University were enrolled. The results of high-frequency ultrasound and elastography technology measuring the thickness, width and shear wave velocity(SWV) of the supraspinatus tendon at 1 month, 3 months and 6 months after surgery were retrospectively analyzed. The visual analog scale (VAS) score and Constant-Murley shoulder joint score of the patients were also collected. The changes of ultrasound indicators of supraspinatus tendon at different periods after surgery were compared, the correlation between ultrasound indicators and VAS scores was analyzed, and the judgment efficiency of each ultrasound indicator for the rehabilitation effect was analyzed based on the Constant-Murley score of 70. 
Results When comparing each other at each postoperative period, there was no significant difference in the width of the supraspinatus tendon on the affected side (P＞0.05), while there was a significant difference in the thickness of the supraspinatus tendon on the affected side between 1 month and 3 months after surgery, and between 1 month and 6 months after surgery(P＜0.05). There was no significant difference in the thickness of the supraspinatus tendon on the affected side between 3 months and 6 months after surgery (P＞0.05). The difference in SWV value of supraspinatus tendon on the affected side was significant between 1 month and 3 months after surgery, between 3 months and 6 months after surgery, and between 1 month and 6 months after surgery (P＜0.05).The difference in thickness and SWV value of the supraspinatus tendon between the affected side and the healthy side was significant at 1 month after surgery (P＜0.05), but the difference in width was not significant (P＞0.05). At 3 months and 6 months after surgery, the difference in SWV value of the supraspinatus tendon between the affected side and the healthy side was significant (P＜0.05), but there was no significant difference in the thickness and width (P＞0.05). Spearman correlation analysis showed that the SWV value had a moderate positive correlation with the VAS score of the shoulder joint (rs=0.591, P＜0.001), while the thickness and width had no significant correlation with the VAS score of the shoulder joint. Based on the Constant-Murley score of 70, the area under the curve (AUC) of the SWV value was 0.781, and the AUC of the thickness and width was 0.531 and 0.466 respectively. 
Conclusion High-frequency ultrasound and elastography technology can evaluate the changes in postoperative morphology and stiffness of patients' supraspinatus tendon in a timely manner. SWV has certain reference value in evaluating VAS and judging the effect of functional rehabilitation, which is helpful to clinicians and rehabilitation physicians to develop an appropriate rehabilitation plan.

Key words: shoulder injuries, high-frequency ultrasound, elastography