12 patients underwent temporomandibular joint (TMJ) reconstruction with Biomet total joint prostheses. Indications for TMJ reconstruction included ankylosis, rheumatoid arthritis, degenerative joint disease and condylar resorption. Five patients had unilateral procedures, seven had bilateral. The follow-up ranged between 2 and 8 years. Amongst the ankylotic patients the mean jaw-opening capacity increased from 3.8 mm preoperatively to 30.2 mm 1 year after surgery, and in most of those patients the opening capacity remained stable over the years. The other patients maintained a mean opening capacity of more than 35 mm. Joint related pain and interference with eating were eliminated after TMJ reconstruction. There were no permanent facial nerve disturbance, no postoperative infections and no device related complications. The outcome supports prosthetic TMJ reconstruction as a useful treatment modality in patients with advanced TMJ disease.
This study addresses the sometimes controversial area of prosthetic reconstruction of the temporomandibular joint (TMJ). In 1995, van L oon et al. reviewed the literature on prosthetic reconstruction of the TMJ. Only three of these devices are in use today: TMJ Concepts (Ventura CA, USA), TMJ Implants (aka Christensen) (Golden, CO, USA), and Biomet/Lorenz (Jacksonville, FL, USA); they have been reviewed by G uarda -N ardini et al. With the exception of TMJ Concepts, there is little literature supporting the use of these devices . The literature on TMJ Concepts also has shortcomings because it is written by a small number of surgeons .
The present author describes the results of his first 12 consecutive patients treated with Biomet (previously Lorenz) total TMJ prostheses (Biomet microfixation, Jacksonville, FL, USA) after a follow-up time of up to 8 years.
Materials and methods
The author’s first 12 consecutive patients treated with the Biomet total TMJ prosthesis are described. The Biomet total TMJ prosthesis is designed as a stock product. In contrast to an individually designed prosthesis, such as TMJ Concepts, it comes in fixed sizes and shapes. It has a fossa component made out of ultra high molecular weight polyethylene. The mandibular component is made of cobalt chromium with a titanium layer sprayed on the surface that faces the bone ( Fig. 1 ). The fossa and mandibular components are available in three different sizes. The mandibular component can be selected from two different designs (standard and narrow). The different sizes refer to the attachments; the condylar head and the fossa bowl are the same size, regardless of the size of the component. The fossa component is attached to the zygomatic arch with self-tapping screws (diameter 2.0 mm); the mandibular component is attached to the mandibular ramus with self-tapping screws (diameter 2.7 mm). All screws are made of titanium.
The surgical approach was through one preauricular incision, and one sub-, or retromandibular incision. As the native condyle was removed, the bone cut was made at the level of the sigmoid notch. Such a wide gap was required to make room for the fossa component.
This prosthesis is a stock device, so the bone had to be shaped to fit it. A specially designed diamond burr was used to flatten out the articular eminence to a contour corresponding to the shape of the fossa component ( Fig. 2 ). A test body/dummy was used during this fitting procedure. Care was taken not to remove too much bone from the eminence, which could have reduced the remaining volume for screw insertion in the zygomatic arch. When this osteoplasty was completed, the fossa component was installed ( Fig. 3 ).
Once the fossa component was installed the patient was put under intermaxillary fixation (IMF). Thereafter the mandibular component was fitted into position. If there was a virgin mandible only a limited flattening of the lateral part of the ramus was required. In cases where there had been a previous rib reconstruction, or other deforming processes, this adjusting osteoplasty could be more demanding. Once the dummy for the mandibular component had a flat, stable support on the bone, the true prosthesis was installed. Care was taken to control the condyle’s position. Ideally, it should be seated in the posterior region of the fossa ( Fig. 4 ).
Intraoperatively, and up to 10 days after surgery, the patients were given i.v. antibiotics against skin micro-organisms. During the procedures when IMF was applied, the surgical field was covered, and after these intraoral sessions, the surgeon and assistant changed gowns and gloves.
The wound bed was carefully rinsed with saline and hydrogen peroxide before closure. The patients did not require any postoperative IMF. They were allowed to function immediately, with freedom to choose any diet. Jaw-opening exercises were instituted immediately after surgery, typically with the aid of a Thera-bite (Atos Medical, Milwaukee, WI, USA), or similar exercise instrument. Patients with ankylosis were instructed to continue their exercises for a minimum of 1 year and patients with other diagnoses for 2–3 months after surgery.
The patients were released from hospital 1 day after surgery. They returned for a check-up and the removal of stitches 1 week later. Thereafter they were seen 1, 3, 6 and 12 months after surgery. After the 12-month check-up they returned for annual visits.
Plain film radiographs were obtained at the first postoperative visit, then at 6 months and at the following annual visits up to 5 years after surgery.
There were nine female and three male patients. At surgery they had a mean age of 29 years (14–53 years). Five patients had unilateral and seven had bilateral reconstructions. Indications for TMJ reconstruction were: ankylosis in five patients; degenerative joint disease in three; condylar resorption in two; and rheumatoid arthritis (RA) in two. Of the ankylotic patients two had previous costochondral reconstructions, each with two episodes of re-operation followed by re-ankylosis despite interpositioned silastic implants. One of these patients had been treated with a unilateral Cristensen total TMJ prosthesis followed by re-ankylosis. A third ankylotic patient had undergone surgery in another hospital where bilateral discectomy was followed by bilateral ankylosis, gap arthroplasty followed, and this was followed by bilateral re-ankylosis ( Fig. 5 ). The remaining two ankylotic patients had post-traumatic ankylosis after condylar crush injuries; they had no previous joint intervention. The two patients with degenerative joint disease both suffered from severe pain. Their diagnoses were established with CT and MRI, and in one of them with additional arthoscopy. Both patients with condylar resorption had in the past undergone two orthognathic surgical procedures each. Their continuous condylar resorption resulted in joint pain and poor occlusal stability. The patients with RA had severely resorbed condyles, and, as a result, anterior open bites ( Fig. 6 ).
The follow-up time ranged between 2 and 8 years (mean 5 years). Two patients died during the follow-up, after 3 and 5.5 years, respectively. The cause of death was not related to the TMJ reconstruction. These two patients are reported with follow-up times up to their last appointments 2 and 5 years, respectively ( Table 1 ).
|Sex||Age||Diagnosis||Uni-/bilateral||Previous surgery||Opening pre||Opening post||Follow-up years|
|Female||27||Ankylosis||Unilateral||2 ribs. Silastic bloc||1||39||7|
|Male||26||Ankylosis||Unilateral||2 ribs. Silastic bloc Christensen||5||20||4|
|Female||43||Ankylosis||Bilateral||Discectomy, gap arthroplasty||0||38||4|
|Female||25||Resorption||Unilateral||Arthroscopy||35||25||5, dead at 5.5|
|Female||20||DJD||Bilateral||Orthogn surg, arthroscopy||20||40||8|
|Female||35||RA||Bilateral||None||35||35||2, dead at 3|