To evaluate the association between rotator cuff tear and the proximal migration of humeral head

In this research, 60 patients with unilateral rotator cuff tear in Peking University People's Hospital in 2018 are planned to be recruited .They will receive Magnetic Resonance Imaging(MRI) and X-ray of the painful shoulder before enrollment in this study, the duration between the two examinations was no longer than 1 week, also there is no past history of surgery in the selected shoulders. There is no other exclusion criteria. Upward Migration Index(UMI) is the ratio between the distance of humeral head center to the lower surface of acromion, and the radius of humeral head circle. It can help to minimize the effect of anatomy difference and imaging magnification, compared with the traditional acromiohumeral distance(AHD). Then we use the Spearman correlation analysis to evaluate the relationship between UMI and fatty degeneration, rotator cuff tear size and the thickness of ruptured supraspinatus tendon from X-ray and MRI.

Inclusion Criteria:

• Patient receive Magnetic Resonance Imaging half year before enrollment, showing supraspinatus tear
• Patient receive X-ray half year before enrollment
• the duration between the two examinations was no longer than 1 week
• no past history of surgery in the selected shoulders

Exclusion criteria:

• patients who cannot receive MRI.

60 patients with cuff tear