Global Fatty Degeneration Index on Preoperative Magnetic Resonance Imaging Predicts Early Postoperative Shoulder Stiffness at 3 Months After Primary Rotator Cuff Repair.

PURPOSE: To determine whether the fatty infiltration of rotator cuff muscles, as measured by magnetic resonance imaging (MRI) preoperatively and assessed using the Goutallier fatty degeneration index (GFDI), can predict early postoperative shoulder stiffness (POSS) after rotator cuff repair (RCR).

METHODS

This retrospective longitudinal cohort study included patients who underwent primary RCR, had available medical records, and underwent MRI before RCR between November 2012 and July 2022. Patients were excluded on the basis of the following criteria: (1) preoperative shoulder stiffness, (2) additional procedures (e.g., biceps tenodesis, labrum repair, stabilization for instability, and distal clavicle resection), and (3) inadequate medical records. Patient demographics, comorbidities, fatty infiltration on the basis of the Goutallier classification from preoperative MRI scans and GFDI scores-calculated from the supraspinatus, infraspinatus, and subscapularis muscles-were recorded. POSS was defined on the basis of range of motion at the 3-month postoperative assessment. χ2 tests and independent t tests were used for group comparisons. Receiver operating characteristic curve analysis determined optimal GFDI cutoff values, and logistic regression assessed POSS risk associated with GFDI.

RESULTS

A total of 388 patients were included; 128 patients were in the POSS group and 260 in the non-POSS group at the 3-month follow-up. Fatty infiltration of the supraspinatus, infraspinatus, and subscapularis muscles was significantly greater in the POSS group compared with the non-POSS group. Receiver operating characteristic analysis yielded an area under the curve of 74.1% for GFDI ≥1.5, with a sensitivity of 83.6% and specificity of 58.8%. Logistic regression revealed an adjusted odds ratio of 5.733 for POSS with mean GFDI ≥1.5 (P = .003).

CONCLUSIONS

Increased fatty infiltration in the rotator cuff muscles, particularly with GFDI ≥1.5, is associated with a greater risk of early POSS 3 months after surgery.

LEVEL OF EVIDENCE: Level III, retrospective case-control study.