Another Assessment of Fat Degeneration of Retracted Supraspinatus Muscle

BACKGROUND: The purpose of this study was to assess the relevance of preoperative magnetic resonance imaging (MRI) evaluation by occupation ratio (OR) at maximum diameter of supraspinatus muscle. METHODS: Patients from the Inje University Sanggye Paik Hospital who received rotator cuff repair and underwent pre- and postoperative MRI were selected as subjects of this study. On T1-weighted MRIs, OR of fat and muscle at Y-shaped view, OR at a location on supraspinatus muscle where its diameter was maximum on coronal view, and pre- and postoperative Goutallier Classification and changes in the tangent sign were measured. Statistical significance of postoperative OR was assessed regarding time from symptom onset to surgery, size of rotator cuff tear, preoperative OR, and the difference between ORs measured at maximum diameter of supraspinatus muscle and Y-shaped view. RESULTS: Preoperative OR at Y-shaped view was 52.28 ± 8.57 (32.5–65.3). Preoperative OR difference between maximum diameter and Y-shaped view was 13.76 ± 10.51 (2.38–42.04), and Pearson correlation coefficient was 0.604 (p=0.001). Postoperative OR at Y-shaped view was 63.77 ± 9.35 (37.3–76.1). Pearson correlation coefficient of pre- and postoperative Goutallier Classification was −0.579 (p=0.002) and Pearson correlation coefficient of the postoperative difference between ORs measured at maximum diameter of supraspinatus muscle and Y-shaped view was −0.386 (p=0.047). CONCLUSIONS: Fatty degeneration of supraspinatus muscle in rotator cuff tear patients should be evaluated not only in the conventional Y-shaped view, but also at location of maximum diameter of supraspinatus muscle to establish patients' therapeutic plan.

Visual MRI Grading System to Evaluate Atrophy of the Supraspinatus Muscle

OBJECTIVE: To investigate the interobserver reproducibility and diagnostic feasibility of a visual grading system for assessing atrophy of the supraspinatus muscle on magnetic resonance imaging (MRI). MATERIALS AND METHODS: Three independent radiologists retrospectively evaluated the occupying ratio of the supraspinatus muscle in the supraspinatus fossa on 192 shoulder MRI examinations in 188 patients using a 3-point visual grading system (1, > or = 60%; 2, 30-59%; 3, < 30%) on oblique sagittal T1-weighted images. The inter-reader agreement and the agreement with the reference standard (3-point grades according to absolute occupying ratio values quantitatively measured by directly contouring the muscles on MRI) were analyzed using weighted kappa. The visual grading was applied by a single reader to a group of 100 consecutive patients who had undergone rotator cuff repair to retrospectively determine the association between the visual grades at preoperative state and postsurgical occurrences of retear. RESULTS: The inter-reader weighted kappa value for the visual grading was 0.74 when averaged across three reader pairs (0.70-0.77 for individual reader pairs). The weighted kappa value between the visual grading and the reference standard ranged from 0.75 to 0.83. There was a significant difference in retear rates of the rotator cuff between the 3 visual grades of supraspinatus muscle atrophy on MRI in univariable analysis (p < 0.001), but not in multivariable analysis (p = 0.026). CONCLUSION: The 3-point visual grading system may be a feasible method to assess the severity of supraspinatus muscle atrophy on MRI and assist in the clinical management of patients with rotator cuff tear.

Is the Supraspinatus Muscle Atrophy Truly Irreversible after Surgical Repair of Rotator Cuff Tears?

BACKGROUND: Atrophy of rotator cuff muscles has been considered an irreversible phenomenon. The purpose of this study is to evaluate whether atrophy is truly irreversible after rotator cuff repair. METHODS: We measured supraspinatus muscle atrophy of 191 patients with full-thickness rotator cuff tears on preoperative magnetic resonance imaging and postoperative multidetector computed tomography images, taken at least 1 year after operation. The occupation ratio was calculated using Photoshop CS3 software. We compared the change between pre- and postoperative occupation ratios after modifying the preoperative occupation ratio. In addition, possible relationship between various clinical factors and the change of atrophy, and between the change of atrophy and cuff integrity after surgical repair were evaluated. RESULTS: The mean occupation ratio was significantly increased postoperatively from 0.44 +/- 0.17 to 0.52 +/- 0.17 (p < 0.001). Among 191 patients, 81 (42.4%) showed improvement of atrophy (more than a 10% increase in occupation ratio) and 33 (17.3%) worsening (more than a 10% decrease). Various clinical factors such as age tear size, or initial degree of atrophy did not affect the change of atrophy. However, the change of atrophy was related to repair integrity: cuff healing failure rate of 48.5% (16 of 33) in worsened atrophy; and 22.2% (18 of 81) in improved atrophy (p = 0.007). CONCLUSIONS: The supraspinatus muscle atrophy as measured by occupation ratio could be improved postoperatively in case of successful cuff repair.