Background:The measurement of cross-sectional area (CSA) is a diagnostic tool to detect entrapments syndrome. The aim of this study was to compare the clinical outcome in elbows undergoing endoscopic and "in situ" open cubital tunnel release for cubital tunnel syndrome (CuTS) using ultrasound-related changes in the largest CSA of the ulnar nerve. The purpose is to determine the association between clinical outcome and CSA. Methods: From May 2011 to April 2016, 60 patients with CuTS were prospectively followed and not randomly divided in two groups: 30 patients undergoing an endoscopic release (ER) and 30 patients with "in situ" open neurolysis (OR). A sonographic examination was performed by the senior authors at baseline and 3, 6, and 12 months after surgical decompression. Results: CSA values were statistically significantly lower in the ER. Hand grip strength difference with Jamar test was not statistically significant a 12 months (39 kg vs 27 kg). Static-2 point discrimination test difference was only statistically significant lower in the endoscopic group at 3, 6 and 12 months but not clinically relevant (5 mm vs 6 mm). The American Shoulder and Elbow Surgeons-Elbow questionnaire (ASES-e) function score, ASES-e Pain score, and ASES-e Satisfaction score were not statistically significant different between the two groups at 3, 6, and 12 months post operatively. Conclusions: The study confirms that in spite of lower values of CSA in the ER, there is not a statistically significant difference between the two techniques in terms of subjective outcomes. Ultrasound (US) measurements seem to have a limited value in clinical results of patients treated for entrapment neuropathy of the ulnar nerve.Type of study/LOE: Prognostic Level III.
Keywords: cross sectional area; cubital tunnel; cubital tunnel syndrome; endoscopic release; ulnar nerve; ultrasound.