Related Experiment Video
Updated: Aug 23, 2026
Screening of Axonal Degeneration in Carpal Tunnel Syndrome Using Ultrasonography and Nerve Conduction Studies
Published on: January 11, 2019
A new clinical test for radial tunnel syndrome--the Rule-of-Nine test: a cadaveric study
Y C Loh1, W L Lam, J K Stanley
1Department of Orthopaedic Surgery, University of Malaya Medical & Specialist Centres, 59100 Kuala Lumpur, Malaysia. ycloh18@hotmail.com
Purpose:
Radial tunnel syndrome refers to pain on the lateral aspect of the forearm as a result of compression of the posterior interosseous nerve within a tunnel with specific anatomical boundaries. Diagnosis of the condition is difficult because of its close association with lateral epicondylitis, which warrants different methods of treatment. Based on a cadaveric study, a new clinical test, the Rule-of-Nine test, is proposed to improve the diagnostic accuracy in radial tunnel syndrome. The test involves constructing 9 equal squares on the anterior aspect of the forearm and noting those squares where tenderness can be elicited.
Methods:
19 upper limbs were dissected to delineate the path of the posterior interosseous nerve through the radial tunnel, and the relationship of the path of the nerve with the 9 squares.
Results:
A consistent mapping of the posterior interosseous nerve to the lateral column of 3 squares was observed.
Conclusion:
The Rule-of-Nine test is proposed as a reliable method of diagnosing radial tunnel syndrome.
Related Concept Videos
01:11Assessment of radial pulse
The radial pulse, located at the wrist, is often the preferred site for assessing peripheral pulse because of its accessibility and dependability. The process of determining the radial pulse involves several steps:
01:21Peripheral Arterial Disease II: Clinical Manifestations and Diagnostic Evaluation