Scratch Collapse Test Localizes Osborne's Band as the Point of Maximal Nerve Compression in Cubital Tunnel Syndrome

The objective of this study is to demonstrate the utility of the scratch collapse test (SCT) in localizing the point of maximal compression in cubital tunnel syndrome. From January 1, 2004 to December 1, 2005, 64 adult patients with cubital tunnel syndrome were evaluated by a single surgeon. Cubital tunnel syndrome was diagnosed based upon symptoms of numbness, tingling, and/or pain in the ulnar nerve distribution or by the presence of weakness or wasting of the ulnar-innervated intrinsic hand muscles. All diagnoses were confirmed with electrodiagnostic studies. As part of the physical examination, the SCT was performed along three subdivided segments in the region of the cubital tunnel. Results of the SCT were recorded and correlated with intraoperative findings. Of the 64 patients evaluated, 44 had a positive SCT that was either more profound or solely present a few centimeters distal to the medial epicondyle in the region of Osborne's band. All of these patients subsequently underwent anterior submuscular transposition and were found to have a tight compression point at Osborne's band corresponding to their preoperative SCT. This study suggests that the scratch collapse test may be a reliable physical examination technique for localizing the point of maximal nerve compression in patients with cubital tunnel syndrome. That point, in this series, corresponded with Osborne's band.