Total reconstruction of the temporomandibular joint. Up to 8 years of follow-up of patients treated with Biomet ®total joint prostheses

Abstract

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.

Fig. 1
(a) Biomet/Lorenz standard total TMJ prosthesis mounted on model skull. The fossa component is produced with three different sizes of the flange over the zygomatic arch. The fossa cup is the same size in all. The mandibular component also comes in a narrow shape ( Fig. 6 b) without the bulb like anterior protrusion shown here. (b) The instrumentation for the Biomet total TMJ prosthesis. In the left kit is a collection of retractors and other instruments. In the right kit are the six test bodies for the fossa components: left and right, small, medium, and large. There are corresponding test bodies for the mandibular components. In the upper right slot the wide diamond burr for shaping the fossa bed can be seen.

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 ).

Fig. 2
After preparation, the eminence has been flattened with a diamond burr giving the inferior part of the eminence a shape corresponding to the superior contour of the fossa component.

Fig. 3
The fossa component is attached to the zygomatic arch with self-tapping 2.0 mm titanium screws.

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 ).

Fig. 4
After intermaxillary fixation the proper mandibular component is installed. Care should be taken that the condylar head is positioned in the posterior portion of the fossa. This arrangement will allow maximum opening capacity.

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.

Results

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 ).

Fig. 5
(a) Shortly after this picture was obtained, the patient suffered disc related problems after a road traffic accident. She underwent bilateral discectomies, but developed bilateral TMJ ankylosis; those were released by gap arthroplasty, followed by re-ankylosis. (b) The re-ankylosis immobilized the jaw in a retrognathic position because of the gap arthroplasty. (c) 1 month after release of the ankylosis and installation of bilateral total joint prostheses. The patient has regained her original profile and occlusion. 4 years after TMJ reconstruction she has an opening capacity of 38 mm.

Fig. 6
(a) Patient with anterior open bite due to RA induced condylar resorption. (b) The same patient 3 years after TMJ reconstruction with Biomet total TMJ prosthesis. Note, that these mandibular components represent the narrow model, in contrast to the one described in Fig. 1 a.

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 ).

Table 1
Total reconstruction of the TMJ. Up to 8 years of follow-up of patients treated with Biomet total joint prostheses.
Sex Age Diagnosis Uni-/bilateral Previous surgery Opening pre Opening post Follow-up years
Male 14 Ankylosis Bilateral None 13 15 7
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
Male 14 Ankylosis Bilateral None 0 37 3
Female 41 DJD Unilateral None 11 35 7
Female 25 Resorption Unilateral Arthroscopy 35 25 5, dead at 5.5
Female 22 Resorption Bilateral Orthogn surg 22 35 8
Female 20 DJD Bilateral Orthogn surg, arthroscopy 20 40 8
Female 35 RA Bilateral None 35 35 2, dead at 3
Female 30 RA Bilateral None 30 44 3
Female 55 DJD Unilateral None 25 35 2
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Feb 8, 2018 | Posted by in Oral and Maxillofacial Surgery | Comments Off on Total reconstruction of the temporomandibular joint. Up to 8 years of follow-up of patients treated with Biomet ®total joint prostheses
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