Background
Acromiohumeral distance (AHD) is considered a prognostic factor for reparability and rotator cuff integrity in arthroscopic rotator cuff repair (ARCR). AHD is measured on a standard true anteroposterior (AP) radiograph, three-dimensional CT, or MRI. However, which image is most useful for predicting reparability and retear is poorly documented.
Purpose
This study aimed to determine which image is most useful for predicting the reparability and retear after arthroscopic rotator cuff repair (ARCR).
Methods
This retrospective study was performed on 457 consecutive patients who underwent ARCR for full-thickness RC tendon tear. The inclusion criteria were patients with full-thickness tears and a minimum of 12 months of follow-up. Patients with a partial-thickness tear, isolated subscapularis tear, osteoarthritis, instability, or a history of previous shoulder surgery were excluded. Radiographs were made with the patients standing, while CT and MRI were taken with the patients on supine position. AHD was measured as the minimum length between the acromion and humeral head on true AP radiography (Rad), coronal and sagittal images of MRI (MRIc, MRIs), and CT (CTc, CTs). Retear after ARCR was defined as Sugaya type IV and V on postoperative T2-weighted MR images. Using the receiver operating characteristic (ROC) curve and the area under the curve (AUC), the ability of each image to predict reparability and retear after ARCR was compared, and the cut-off point of each image was determined.
Results
379 patients met our inclusion criteria for repairability and 348 for retear (retear rate:18.4%). For the prediction of repairability, the AUC of Rad, MRIc, MRIs, CTc, and CTs, were 0.740, 0.87, 0.802, 0.792, and 0.805, respectively. For the prediction of RCI, the AUC of Rad, MRIc, MRIs, CTc, and CTs were 0.702, 0.735, 0.752, 0.764, and 0.765, respectively. There was no significant difference in the AUC of images for reparability and retear. Cut-off values for reparability of Rad, MRIc, MRIs, CTc, and CTs were 5.8, 4.9, 4.5, 4.8, and 4.3mm, respectively. Cut-off values for retear of Rad, MRIc, MRIs, CTc, and CTs were 7.8, 6.3, 6.8, 5.6, and 5.6mm, respectively.
Conclusion
There was no significant difference in predicting reparability and retear after ARCR measuring AHD on any type of imaging. Care should be taken to interpret the cut-off values for predicting reparability and retear. The cut-off values of radiographs are 1~2mm greater than those of CT and MRI.