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J Oral Mawllofac Surg

49379-380. 1991

Discussion

The Value of Arthrography in the Decision-Making Process Regarding

Surgery for Internal Derangement of the Temporomandibular Joint

Leslie B. fieffez, DMD, MS University of Illinois at Chicago

The authors discuss the value of arthrography in the surgical decision-making process and conclude that cur- rently it is largely of little benefit. They do make the point, however, that historically the technique moved the profession to better understand the concept of internal derangements as it applies to the temporomandibular joint (TMJ). I agree that arthrography rarely has a place in the primary evaluation of the patient. I find fault, how- ever, in the design of the experiment used to prove this point.

There are two distinct steps in the critical evaluation of arthrography in the decision-making process. The first step is to determine the value of arthrography in the de- cision of whether to operate or not. This point is rela- tively easy to prove. As the authors indicate, the only criteria for surgical intervention are pain and disturbances in the range of motion that are disabling to the patient and refractory to a course of nonsurgical therapy. For many years, practitioners have recognized that objective evi- dence of an internal derangement is not an absolute indi- cation for nonsurgical/surgical intervention. This is not stated from a historical vantage point. The authors make the excellent point that there is no information that may be derived from imaging that can act as an accurate pre- dictor of a successful surgical outcome. Furthermore, it is rarely of any value in the screening process of patients.

The second step in the evaluation of arthrography in the decision-making process is to evaluate its value in helping to make intraoperative decisions. A pure and ap- plied scientist might approach this problem by making the statement that arthrography is of value and then going about disproving the premise. This approach would re- quire enumerating all those factors involved in the deci- sion tree at the time of surgery. If the arthrogram, with its low incidence of false-positives, revealed diagnostic in- formation in only 50% of cases and the information gained was of invaluable intraoperative significance, then we would be justified in its use. The authors do not evaluate arthrography along these lines and, therefore, fail to dis- prove the premise. Correlation of arthrographic findings of disc displacement and perforation of the posterior at- tachment with findings on gross surgical examination do not achieve this end. Disc morphology, disc length, di- rection of disc displacement, thickness of fibrous cap on the condyle or eminence, and state of bony remodeling are other factors to consider in the TMJ equation. The significance of each of these factors has not been deter- mined. How these factors interface with operative deci- sion-making is probably operator-dependent. For exam- ple, I have rarely performed a discoplasty. My operative decision was based, in part, on the degree of discatrophy, reduction in disc length, and alterations in disc morphol- ogy. I question the ability to obtain all this information on gross or arthroscopic examination.’ Lastly, not having this information available preoperatively may impact on the operative time.

Today, surgeons who operate on the TMJ find them- selves at an important historical crux. Up to now, a lim- ited number of closed surgical (arthroscopic) and a myr- iad of open surgical (arthrotomy) procedures have been proposed, with variable degrees of success reported. Es-

DISCUSSION

tablishing a decision-making tree for these procedures is a Sisyphean task, as selection of a procedure is based in many cases on operator preference. We are still young in understanding those factors relevant to surgical decision making, principally because the state of TMJ therapy re- mains very much at an artistic rather than scientific level. Now, arthroscopic procedures for internal derangements are generally considered the first bastion of surgery. With arthroscopy, we are generally evaluating only topograph- ical anatomy of the superior joint space. The art of ar- throscopic procedures is still at a low level of sophistica- tion, especially when we persist in miniaturizing arthrot- omy procedures. We, therefore, do not know how imaging should relate to the arthroscopic decision-making process. I believe magnetic resonance imaging, for exam-

ple, will prove of value in establishing guidelines for dif- ferent stages of the disease process. This, however, re- mains in the infantile research stage, and is an argument against routine imaging. The authors have taken on a dif- ficult task and should be lauded in their attempts to halt an abuse of medical imaging/testing. Moreover, we should remember that recognition of abuse is a step in the learning process.

Reference

1. Isaacson A, lsberg A, Johansson AS, et al: Internal derange- ment of the temporomandibular joint: Radiographic and histological changes associated with severe pain. J Oral Maxillofac 44:771, 1986