lesions of the anterior interosseous nerve are rare and comprise less than 1% of all upper extremity nerve palsies . traumatic causes include blunt trauma , forearm fractures , penetrating injury and local pressure from a plaster cast , but has never before been described in association with crutch use . this is the first reported case of the use of elbow crutches causing symptomatic anterior interosseous nerve compression . this case describes a 30-year - old male who developed an inability to pinch with his left hand following the use of elbow crutches for a foot injury . on examination a diagnosis of anterior interosseous palsy was made and the patient was treated conservatively and crutch use was ceased . at six weeks follow - up the patient made a complete recovery with full function of his left hand . this report highlights the importance of adequate education in the safe use of elbow crutches for all patients . the side effects of inappropriate use should be carefully examined for during follow - up care . lesions of the anterior interosseous nerve [ ain ] are rare and comprise less than 1% of upper limb palsies . it is an exclusively motor branch of the median nerve and provides innervation to flexor pollicis longus , the medial part of flexor digitorum profundus involving the index and sometimes the middle finger , and to pronator quadratus . entrapment of the nerve results in a characteristic appearance on pinching , which may be mistaken for a tendon rupture . we present a case of a patient who developed ain palsy following the use of elbow crutches . a 30-year - old fit and healthy male presented to fracture clinic four days after suffering a stubbing injury to his left big toe and superficial abrasion to his left heel . x - rays reviewed an undisplaced fracture of the base of the left little toe distal phalanx . he was given elbow crutches with instructions for partial weight bearing on the affected leg and discharged with a fracture clinic appointment . in clinic , the patient complained of a gradual onset of difficulty in pinching and gripping objects with his left hand since the injury . [ figures 1 and 2 ] movements of the left index and middle fingers were normal and there were no areas of paraesthesia . since there was no history of trauma or predisposing conditions , we believe the patient developed an anterior interosseous nerve palsy following the inappropriate use of elbow crutches over four days . he was subsequently placed in a plaster cast boot and was advised to fully weight bear without the use of crutches . however , by the time he came to a six - week follow - up clinic after the injury , he had made a complete clinical recovery in hand movement and function . many causes for ain palsy have subsequently been described in literature , and can be divided into traumatic and non - traumatic / spontaneous . traumatic causes range from blunt trauma , local pressure from sleeping on the affected arm or poorly applied cast , excessive exercise , penetrating injury , forearm fractures and open reduction and internal fixation . to our knowledge ain palsy can be described as complete , where flexor digitorum profundus and flexor pollicis longus are both affected , or incomplete , where only one muscle is affected . it differs from other lesions of the median nerve in that sensory complaints are essentially absent . as a result of these factors , ain palsy can often mimic single tendon lesions , leading to difficulties with diagnosis . in the literature , there are cases of ain entrapment with unnecessary surgical exploration of fpl tendon . o with the thumb and index finger , and the loss of ability to perform fine tasks despite an intact sensory innervation . spontaneous ruptures of flexor pollicis longus tendon are rare and are generally associated with distinct underlying pathologies , such as rheumatoid arthritis . several clinical tests have been described to distinguish between palsy of fpl and rupture of this tendon[810 ] . electrodiagnosis with nerve - conduction study or electromyography is the investigation of choice to differentiate between nerve palsy and tendon rupture . in the present case , however , the patient made a full recovery before electrodiagnostic studies could be carried out , thereby ruling out the possibility of rupture of flexor pollicis longus . conservative management includes removal of precipitating causes such as crutches and casts , immobilisation and anti - inflammatory medication . we believe all patient should be taught safe and effective usage of elbow crutches when they initially receive them . the side effects of inappropriate use should be carefully examined for during follow - up care .