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Chapter 238as impressive as its quick rise in popularity, and this resulted in many surgeons temporarily avoiding the use of alloplastic TMJ TJR. Within 10 years after its first use, the FDA recommended the recall of all patients treated with the Vitek disc prosthesis, following which the AAOMS and FDA recommended removal of the implant, as expanded on in the Discussion section.(12,18,37)In 1983, Sonnenburg and Fethke developed the first version of their prosthesis. The titanium/palladium alloy condylar part had a spherical head connected to a base. This base was fixed on the mandible where the autologous condyle had originally been, using a plate with five screw holes. The fossa component was made from high-pressure polymerized polyethylene and was fixed to the articular tubercle with a single screw. To assure a precise fit and sufficient fixation, PMMA cement was used between the fossa component and the base of the skull. (11,18,19) The fossa for this first version was developed based on cephalometric tracings of the patient’s fossa, making the system somewhat a patient-specific implant. With production in mind, Sonnenburg and Sonnenburg(38) (OCEBM LOE IV) then designed a new polyethylene fossa prosthesis with a reduced antero-posterior dimension, although fitting and fixation was still done using PMMA cement.(19)In 1989, Techmedica developed a patient-specific total TMJ replacement system using data obtained from computed axial tomography scans of a patient’s skull. The prosthetic joint was first designed on a computeraided design/computer-aided manufacturing (CAD/CAM) system and fitted to a replica of the patient’s skull. Differences in patient-specific occlusion, jaw position, and anatomy could be adjusted at the design level and then checked at the construction level. The fossa component consisted of titanium mesh coated with UHMWPE.(12,18,19,39,40) The titanium mesh allowed for bony and soft tissue ingrowth, furthering the fixation in addition to the three to four screws that were placed in the zygomatic arch. The condylar component of the prosthesis was composed of a titanium alloy shaft and a cobalt-chrome-molybdenum (CoCrMo) alloy head. It was fitted to the mandible using six screws, although this number was increased after reports of stability problems.(19) The Nikolas de Meurechy NW.indd 38 05-06-2024 10:14