Validity of computed tomographic measurements and morphological comparison of cubital tunnel in idiopathic cubital tunnel syndrome

BACKGROUND: Ulnar neuropathy is a common reason for referral to hand surgeons, and 10 to 30% of cubital tunnel syndrome (CuTS) is idiopathic. We hypothesized that the cause of idiopathic CuTS is in the bony structure. METHODS: We analyzed 79 elbows (39 idiopathic CuTS and 40 without CuTS symptom) using computed tomography and Materialize Mimics software to compare the differences between the two groups. We proposed a new bony cubital tunnel with a new boundary that could play a role in ulnar nerve compression symptom. RESULTS: The mean cubital tunnel volume was 1245.6 mm(3) in all patients, 1180.6 mm(3) in CuTS patients, and 1282.3 mm(3) in the control group. A significant difference (p = 0.015) between two groups was found. Bony cubital tunnel cross-sectional area, cubital tunnel depth, and cubital tunnel angle also showed significant differences. CONCLUSION: The shape of the bony cubital tunnel is an important cause of CuTS, and the normal variation of the volume and cross-sectional area of the cubital tunnel and cubital tunnel angle could influence the occurrence of idiopathic CuTS.