During the past 5 years polyethylene has been employed with increasing frequency in middle ear surgery. One of the problems encountered postoperatively is that of dislocation of the prosthesis. Sheehy and House1 reported that the most frequent cause of failure observed, when performing surgical revisions in which polyethylene struts had been employed, was either displacement of the prosthesis or a prosthesis which was too short. After stapedectomy for otosclerosis, Shea2 observed a patient with initial hearing improvement which was subsequently suddenly lost; the upper end of the polyethylene tubing had become dislocated from the incus. Sooy3 not only reported 2 patients with dislocated struts, but also 4 patients in whom the prosthesis had perforated the absorbable gelatin sponge (Gelfoam) graft. Hildyard4 had a patient return 3 days postoperative with loss of hearing, vertigo, and nausea following a head injury. He found the prosthesis projecting into the