A 55 year old male presented to the surgery outpatient service with weakness of thumb and index finger flexion of the right hand after previous shoulder surgery a few months prior. History was significant for Leriche syndrome with stent implantation. Clinical examination revealed an inability to form an "O" (or "O.K."-sign) with his right thumb and index finger, i.e. a weakness of flexion of the distal joints, indicating a lesion of the flexor pollicis longus and digitorum profundus muscles. No other pathological findings were noted. An external ultrasound exam of the right forearm had shown intact tendons, but an unspecified "edema of the flexor muscles" (images not available).