Use of acrylic spheres as spacers in staged temporomandibular joint surgery

Abstract

Reconstruction of the complex temporomandibular joint (TMJ) patient requiring a custom-made total joint prosthesis necessitates a preoperative computed tomography (CT) scan of the jaws and TMJ structures before fabrication of the prosthesis.1-3 The data obtained from the CT scan are used to manufacture an anatomically accurate plastic model of the TMJ and jaw structures from which the custom-made total joint prostheses are fabricated. Two-stage surgery may be required in some cases where the first surgical procedure is needed to prepare the TMJ and mandibular ramus areas for the CT scan.2,3 Some indications for a staged approach include: 1) ankylosis or heterotropic bone development where significant recontouring and debridement of the fossa are required;3 2) previously placed rib or sternoclavicular grafts requiring extensive recontouring of the ramus; 3) removal of failed Proplast-Teflon implants (Vitek Inc, Houston, TX) with an associated foreign body giant-cell reaction requiring extensive debridement;4 4) septic TMJ or ramus requiring debridement; 5) removal of previously placed metal joint prosthetic components or the presence of ferromagnetic metal in the TMJ or ramus region that may interfere with obtaining a good quality CT scan; and 6) removal of a tumor from the TMJ region.3 Once the condylar segment or prosthetic components have been removed or extensive recontouring of the TMJ has been completed during the first stage of surgery, vertical instability of the mandible can occur. In bilateral cases, this loss of vertical dimension can lead to immediate and progressively increasing retrusion of the mandible, resulting in the development of a severe Class II skeletal relation and an anterior open bite.5 Severe sleep apnea symptoms may develop with increasing retrognathia of the unstable mandible.5 Foreshortening of the muscles of mastication and suprahyoid musculature occurs as a result of loss of vertical dimension, making the second-stage of surgery more difficult, with less predictable results, and often requiring extensive muscle detachment and coronoidectomies. In unilateral cases, shifting of the mandible toward the operated side can lead to migration of teeth, malocclusion, and increased loading and symptoms in the contralateral TMJ. To minimize these adverse effects, maxillomandibular fixation (MMF) has usually been used for the time between the surgical stages (usually 6 to 12 weeks). However, prolonged use of MMF can result in the following consequences: 1) pain and discomfort; 2) airway problems; 3) gingivitis and inflammatory periodontal disease; 4) significant mobility and extrusion of the anterior teeth and intrusion of the posterior teeth, leading to difficulty in controlling the occlusion after the second stage of surgery because of significant “orthodontic” relapse potential; 5) speech and communication difficulties; 6) dietary and nutritional deficiencies; and 7) severe oral hygiene limitations resulting in dental decalcification and caries development. Another problem seen in staged TMJ surgical reconstruction is that postoperative scarring and fibrosis frequently occur after the first stage of surgery. Scar contracture can cause progressive retrusion of the mandible and often makes the surgical dissection at the second surgical procedure technically more difficult and time consuming. This report describes a technique developed by the senior author (L.M.W.) of placing acrylic spheres (Storz Ophthalmics, Rochester, NY) in the joint space during the first surgical procedure to temporarily fill the void created by the removed condyle or prosthesis (Fig 1). The use of such spacers helps provide some vertical stability to the mandible, obviates use of MMF, and decreases the amount of scarring and fibrosis in the joint space, thereby making the second stage of surgery easier. *Formerly, Fellow Oral and Maxillofacial Surgery, Baylor College