This proposal's objective is to challenge and expand the current definition of rotator cuff healing by investigating tendon retraction - broadly defined as medial translation of the repaired tendon away from the bone with or without a defect - as a common and clinically predictive structural outcome following rotator cuff repair. The investigators' central hypothesis is that failure with continuity is a common yet unrecognized structural phenomenon of rotator cuff healing that is significantly and meaningfully correlated with clinical outcomes. The investigators' approach is to characterize tendon retraction using an array of implanted radio-opaque markers, and investigate its relationship to pre-operative tissue quality (MRI), post-operative repair structural integrity (MRI) and clinical outcomes in a 125-patient prospective cohort study. These patients will complete (1) validated questionnaires and range of motion testing pre-operatively, (2) CT imaging at day of surgery, 3 weeks, 3 and 6 months, and 1, 2 and 5 years post-operatively, (3) MRI at 3 weeks, 3 and 6 months, and 1, 2 and 5 years post-operatively and (4) questionnaires, range of motion and strength testing at 3 and 6 months and 1, 2 and 5 years post-operatively.

Currently, rotator cuff healing is defined as "intact", "attenuated", or "failed" based on the observation (or not) of a recurrent defect (i.e., a "gap") in the tendon using MRI or ultrasound imaging. The investigators' previous work has identified a new outcome, in which there is no detectable defect or "gap" in the repaired tendon, but the repaired tendon has undergone significant retraction. The investigators call this outcome "failure with continuity".

Current imaging methods are inadequate to determine the extent to which the repaired rotator cuff tendon has "failed with continuity". The investigators have developed an imaging technique to detect this phenomenon. Specifically, radio-opaque markers are sutured onto the repaired tendon. The distance between the tendon markers and the bone is measured from CT scans taken within 2 weeks of surgery, and compared to the distance measured at 3 and 6 months and 1, 2 and 5 years post-operatively. If the tendon retracts away from the bone during healing, this distance will increase over time. Healing of the tendon will also be monitored in the traditional manner by MRI scans at the same time points. The investigators will investigate the relationship between tendon retraction, MR imaging and clinical outcomes including shoulder strength and patient satisfaction.

The investigators expect to show that tendon retraction is common, occurs early post-operatively, with or without repair continuity as assessed by traditional imaging, and significantly correlates with clinical outcomes. The immediate and highly significant consequence of this finding would be a paradigm shift in the investigators' understanding of tendon repair healing, now incorporating the magnitude, timing and location of tendon retraction as well as the continuity of the repaired tissue. This information would yield a more precise understanding of rotator cuff tendon healing, allowing for advances in treatment strategies that improve surgical healing and clinical outcomes and result in more durable rotator cuff repairs over time.

Inclusion Criteria:

• Males or females, ages 18-75 having an acute or chronic 1-5 cm wide (A-P) full thickness tear of only the supraspinatus and/or infraspinatus tendons; partial thickness tears of subscapularis or teres minor not requiring repair are allowed.
• The tear must be fully reparable arthroscopically by a double row technique.
• Final determination of eligibility will be made at surgery when above inclusion criteria are confirmed.

Exclusion Criteria:

• Prior shoulder surgery (including rotator cuff repair)
• Symptomatic cervical spine disease
• A frozen shoulder-- defined as a loss of passive range of motion (ROM) of more than 20° in any plane compared to the contralateral shoulder,
• Glenohumeral arthritis grade 3 or 4-- defined as full thickness cartilage loss on MRI and confirmed at arthroscopy
• Worker's compensation cases
• Subscapularis tears of any size that require repair

The Study Population includes males and females between the ages of 18-75 who are undergoing arthroscopic rotator cuff repair surgery. Patients will be enrolled on a first come basis. No specific study demographic is necessary or desired.