Mononeuropathy after surgery may occur and hereditary neuropathy with liability to pressure palsies is a possible pathological condition related to paresis after hip surgery. We present a case of 66-year-old man presenting severe weakness at inferior limb muscles after hip prosthesis revision. Clinic and electrophysiology showed severe right fibular nerve damage and ultrasound found a marked enlargement of the same nerve, associated with focal enlargements in other nerves. A diagnosis of hereditary neuropathy with liability to pressure palsies was suspected and confirmed by genetic test. The patient gradually recovered returning to a normal daily active life. Ultrasound was crucial for diagnosis. The suspicion and diagnosis of latent neuropathy, which can occur after surgical intervention, may lead to a better understand of the risks of the surgery, specific for the patient, and avoid the wrong attribution to surgical malpractice.