Ulnar Nerve Injury and Froment's Test: A Case Report

Traumatic, peripheral nerve injuries can be easily missed in the emergency department. The attending physician needs to maintain a high index of suspicion when reviewing patients with extremity injuries. We present a case of a stable, 28-year-old male sustaining penetrating trauma to his right forearm with resultant, isolated ulnar nerve transection. Clinical findings and related anatomy are discussed pertaining to this patient's injury, with specific reference to Froment's test. This is a useful clinical adjunct when reviewing potential ulnar nerve injuries, demonstrating disruption of specific motor innervation to the thumb when such pathology exists. As a result, compensatory hyperflexion occurs with attempted thumb adduction, due to intact median nerve innervation of flexor pollicis longus. Early recognition of this pathology, whether isolated or concomitant, allows for early appropriate referral and improved patient outcomes.