this video describes elson's test as well as a simple modification which can be used for the diagnosis of central slip injuries of the extensor tendon overlying the proximal interphalangeal joint here you see a patient who sustained a laceration over their pip it's short but fairly deep the patient is asked to flex their injured pip at 90 degrees over a table or other 90 degree surface the patient is then asked to extend the pip joint against resistance the job of the examiner is to notice not just their pip extension strength but also whether there's activation of extension at the dip joint which is abnormal this is because the extensor tendon overlying the pip joint is not just a single ten but actually a network of tendons composed of a central slip as well as two lateral bands if the central slip is lacerated those lateral bands can then migrate in a volar direction and become extensors of the distal interphalangeal joint so let's take a look at elsincest one more time absent or weakened extension at the pip joint coupled with fixed extension at the distal interphalangeal joint comprises a positive elsen's test a sign of a central slip rupture if you find this difficult to perform a modification of elsin's test was described in the british journal of hand therapy in 2006. test is a test of symmetry the patient takes the injured finger and places it as pictured pushing against the matching finger of the contralateral hand when the central slip is intact it has a check rain effect on the lateral bands preventing them from becoming activated and therefore resulting in a semi-flexed and floppy distal phalanx as pictured here in an abnormal test when there is an injury to the central slip what you might instead see is asymmetry as pictured here as depicted by the cartoon drawing when the central slip is injured those lateral bands can now migrate in a voila direction and act as extensors at the distal phalanx central slip injuries are very important injuries for the emergency physician and acute care practitioner to detect that's because missing these injuries can result in the delayed consequence of formation of the boutonnaire's deformity as pictured here once the boutonniere's deformity has occurred it can be very difficult for even an experienced hand surgeon to fix to learn more about this injury and other techniques in wound care visit www.lacerationrepair.com