Morphological characteristics of the medial epicondyle-olecranon ligament and the diagnostic accuracy of ultrasound: facilitating precision treatment of cubital tunnel syndrome

Few studies have explored the detailed intraoperative morphology of the Medial epicondyle-Olecranon (MEO) ligament associated with ulnar nerve entrapment, or applied these findings to guide clinical practice for cubital tunnel syndrome (CuTS). This study aimed to comprehensively evaluate the morphological characteristics of the MEO ligament, and to assess the accuracy of preoperative ultrasound in the diagnosis and treatment of CuTS by analyzing the surgical outcomes of small incision in situ decompression (SID) for MEO ligament resection. Data from 16 patients in the SID group, 20 patients in the ulnar nerve transposition (UNT) group, and 12 healthy volunteers were included. The mean intraoperative length, width, and thickness of the MEO ligament at elbow extension were 13.58 mm, 8.87 mm, and 0.72 mm, respectively. The intraoperative thickness of the MEO ligament was significantly greater than the ultrasound measurements in both patients and healthy controls ( p < 0.001). Similarly, ultrasound measurements in patients were significantly greater than those in healthy controls ( p = 0.001). Preoperative motor nerve conduction velocity (MNCV) had a moderate to strong negative correlation with intraoperative MEO ligament thickness ( r = -0.635, p = 0.003) and with ultrasonic thickness ( r = -0.485, p = 0.03). These results suggest that the MEO ligament morphology may serve as a promising supplementary indicator for guiding the diagnosis and surgical planning of CuTS. At 1 year postoperatively, both groups showed significant improvement in follow-up parameters compared with baseline, with no statistically significant differences between groups. Surgical outcome comparison suggests that preoperative ultrasound can accurately visualize MEO ligament morphology and its associated pathological changes, thereby assisting SID in achieving effective treatment of CuTS. These results may aid in formulating personalized surgical methods to treat CuTS.