Elson test

The Elson test was described in 1986 as a clinical test for isolated central-slip injury. The patient flexes the proximal interphalangeal joint to ninety degrees over the edge of a table; the examiner asks the patient to extend the PIP against resistance while observing the distal interphalangeal joint. A normal central slip permits PIP extension while the DIP remains relatively floppy. Central-slip disruption causes the patient to compensate by recruiting the lateral bands to extend the PIP, producing an unnaturally rigid DIP joint as the lateral bands tense. The forces detectable by the test in the immediately post-injury digit are small and may be clinically imperceptible; sensitivity improves with repeated motion cycling, supporting re-examination at five to ten days when the initial test is equivocal.