Letter to Editor JMOS

Dear Sir,

Re: Is eminectomy effective in the management of chronic closed lock?

Authors—Ketan Shah, Andrew Brown, Robert Clark, Mohammed Israr, Donald Starr, Leo Stassen.

I read this retrospective review of the 16-year experience of three units practice between 1995 and 2011 [1] and would make the following comments to clarify issues for trainees in TMJ surgery, which were made in the paper, but perhaps not clearly enough.

In my opinion, and that of many other specialist TMJ surgeons, “closed lock” is an outmoded term which describes limited mouth opening which improves with manipulation—locking on opening is perhaps more descriptive. It can be caused by a number of factors which include pain from within the joint or from muscle spasm, lack of lubrication within the joint (anchored disc phenomenon [2]) or immobility of the articular disc. The traditional suggestion is that the disc is displaced anterior to the eminence and does not reduce and hence eminectomy removes the block. Current management would be to fully assess whether the eminence is the cause of the blockage or whether this is due to muscle spasm secondary to pain (from disc tear or retrodiscal thickening/synovitis) or a lack of lubrication. Following a period of conservative management—rest, NSAIDs, bite splints and muscle massage—a failure to improve would indicate arthrocentesis or preferably arthroscopy to support a more accurate diagnosis of the cause of the restriction [3]. The experience of many authors is that this is sufficient to relieve symptoms in 70–80% of cases [4], leaving eminectomy redundant as a first-line treatment option in the twenty-first-century practice.

What is of more concern is that some cases have been referred to my care where eminectomy has failed to provide relief and invariably on repeat exploration a disc tear is located and removal of the offending disc provides relief of symptoms. The question remains as to whether the tear was present and missed at the time of eminectomy or was a result of the procedure, but was certainly the cause of failure and would have been diagnosed by arthroscopy [3].

Whilst TMJ arthroscopy is outside the common remit of many maxillofacial colleagues, I would suggest that there are sufficient surgeons with this expertise to warrant onward referral rather than opening a joint and predisposing to degenerative changes.

All that being said, as a second-line procedure where the eminence is steep, there is lateral lipping or degenerative changes; it is an appropriate consideration provided other pathology within the joint is assessed and managed at the same time. This article gives good evidence to support it as a safe technique with good outcomes.