TMJ Surgery: The Total Joint Replacement
Total fusion (ankylosis) or severe arthritic destruction of the TMJ by systemic arthritic conditions such as rheumatoid, juvenile rheumatoid, psoriatic or severe osteoarthritis is a severe human impairment. When fusion occurs, the ability to open the mouth decreases sometimes to less than the width of a finger.
Historically, an operation removing the fused bone would temporarily correct the problem. However, one mechanical problem that the TMJ has is that with all motion and function, tension forces are produced. (unlike knees or hips where compression forces predominate) bone has the tendency to grow when placed under tension. Consequently, a condition known as heterotopic bone formation can occur rapidly and create problems with joint immobility all over again.
Transplantation of ribs with cartilage on them to act as condyle substitute has been used. This operation has a place in some conditions, but there are significant problems when the joint must be replaced because of a systemic arthritis. The arthritic condition can also attack the transplanted bone graft. Ribs can also fuse again over a period of years.
It is clear that in maxillofacial surgery, multiple surgery of the TMJ patient has significant limits. Dr. Louis Mercuri at Loyola University in Chicago has analyzed records of many TMJ surgery patients and their clinical courses and concluded that pain management and function do not improve much after 3 “conservative” operations to manage a deteriorating and severely arthritic joint. To that end, any operating surgeon must apply the proper initial procedure to meet the pathology of the TMJ. The unique biomechanics of the jaw joint can cause deterioration in advanced arthritis and total replacement must be considered as an option. In cases of severe malocclusion associated with joint arthritis and condlye resorbtion, total replacement can be considered initially.
There have been 3 generations of Total TMJ Surgery replacement systems: Kent, Christensen, and now TMJ Concepts (developed by Mercuri…..see TMJConcepts.com) and the Quinn prosthesis, developed by Peter Quinn at the University of Pennsylvania, and produced by Biomet.
The TMJ concepts prosthesis is a custom made prosthesis, The Biomet system is a manufactured or “stock” system. Both have their places in clinical application. Both have good long term follow up data. Selected surgeons in the United States, Europe, Canada, South America, and Asia are employing these devices earlier in their management of TMJ fusion and arthritic destruction.
Patients who would need a total joint replacement would be wise to consult with an experienced surgeon. Consult ASTMJS.org for a list of members of the American Society of TMJ Surgeons as well as International members capable of performing this operation.