The Hook Test Is Not Pathognomonic for Foveal Detachment of the Triangular Fibrocartilage

Background  The integrity of the foveal insertion of the triangular fibrocartilage complex (TFCC) is currently assessed by inference using the hook test. Using dry arthroscopic techniques, the primary author observed that many patients with painful distal radioulnar joint (DRUJ) instability and a positive hook test had an intact foveal insertion. This study was performed to determine whether a positive hook test is a reliable index of a tear of the foveal insertion. Technique  The hook test is performed using a probe to elevate the TFCC off the ulna head toward the articular surface of the lunate. In this study, the hook test was considered positive if the TFCC could be elevated to bridge more than 80% of the space between the TFCC and the articular surface of the lunate. Patients and Methods  A retrospective study was performed using the medical records and arthroscopic videos of 113 patients who had clinical signs of DRUJ instability and underwent arthroscopic surgery performed by the primary author in 2020. It was documented whether the hook test was positive or negative, whether the foveal insertion was intact, abnormal or absent, and whether there were peripheral (dorsal or volar) tears of the TFCC. Sensitivity and specificity were calculated using arthroscopic findings as the reference standard. Results  The sensitivity of the hook test was found to be 100%, and the specificity was 7.0%. The positive predictive value for foveal pathology was found to be 12.3% and the negative predictive value 100%. The diagnostic accuracy of the hook test in determining the presence of foveal tears was found to be 17.7%. The diagnostic accuracy of the hook test in determining the presence of a TFCC abnormality was 99.1%. Conclusions  A positive hook test is indicative of a tear of the TFCC, but it is not anatomically specific for a tear of the foveal insertion. To reliably assess the foveal insertion, it must be visualized and probed using dry arthroscopic techniques.