Modified Cut for Gap Arthroplasty in Temporomandibular Joint Ankylosis.

Temporomandibular joint ankylosis is a debilitating disease affecting the function, esthetics and psychology of the patient. Treatment of this condition aims at establishing not only the function and esthetics but also aims to prevent reankylosis. Among the different treatment modalities, interpositional gap arthroplasty followed by aggressive jaw physiotherapy is considered most effective. This is achieved by making two horizontal osteotomy cuts at a distance of 10-15 mm in the TMJ region. The gap is then interposed with an autogenous or alloplastic graft material. However, during the application of a jaw stretcher intraoperatively with the surgical site open and with the jaw wide open, a bony contact was seen to occur between the posterior aspect of the upper and lower osteotomy cuts. Taking this into consideration, the lower osteotomy cut is modified by making the posterior one-third cut divergent. This eliminates the bony contact during maximum mouth opening and thus prevents the chances of reankylosis as well. Copyright:

INTRODUCTION

Temporomandibular joint (TMJ) ankylosis is a fusion of the articular surfaces of the mandibular condyle and the glenoid fossa which may be bony or fibrous. This fusion severely restricts the jaw movements and its growth, especially if it develops during the growth period of the patient. This disabling condition not only causes facial deformities, speech impairment, difficulty in mastication, reduction in the airway space but is also psychologically distressing for the patient.[1]

Treatment of this condition is equally challenging and aims primarily at establishing function and esthetics with adequate measures to prevent reankylosis. Among the different treatment modalities, interpositional gap arthroplasty followed by aggressive jaw physiotherapy is considered most effective.[2] Interpositional gap arthroplasty is the surgical removal of the ankylosed mass to create a gap between the glenoid fossa and the ramus stump. This is done by making two horizontal osteotomy cuts at a distance of 10–15 mm in the TMJ region [Figures 1 and 4a].[3] The gap is then interposed with an autogenous or alloplastic graft material. Contact between the two bony surfaces can predispose to reankylosis which is prevented by making proper osteotomy cuts, creating an adequate gap, and using interpositional graft material.

Figure 1

Gap arthroplasty showing adequate space between the two surfaces when the mouth is closed

Figure 4

Intraoperative image showing (a) temporomandibular joint gap arthroplasty with the cuts made parallel to each other, (b) contact seen at the posterior aspect of the two osteotomy cuts during maximum mouth opening, (c) modified osteotomy cut marked, (d) no bony contact seen after making the modified osteotomy cut during maximum mouth opening

However, during the application of a jaw stretcher intraoperatively with the surgical site open, we observed that during maximum mouth opening, a bony contact was seen to occur between the posterior aspect of the upper and lower osteotomy cuts [Figures 2 and 4b]. It was clear that this contact could predispose to a reankylosis. Taking into consideration, this possibility and as a measure to prevent the patient from going through the same psychological stress of reankylosis, we introduced a simple modification in the osteotomy cuts which we have been following for the past 5 years in 37 of our ankylosis patients.

Figure 2

Bony contact seen at the posterior aspect of the joint on maximal mouth opening

TECHNIQUE

A preauricular incision is taken, and layer-wise dissection is done to expose the ankylosed joint, zygomatic arch, coronoid process, and ramus stump. While taking adequate care of the structures on the medial aspect of the joint and proximity of the middle cranial fossa superiorly, a superior osteotomy cut is made conventionally by relating to the surrounding identifiable structures and thus separating the ramus stump from the skull base. The inferior osteotomy cut is made parallel to and at a distance of 1–1.5 cm in the anterior two-third aspect of the cut. The posterior one-third of the lower cut is made divergent and is directed inferiorly away from the superior osteotomy cut [Figures 3, 4c and d]. After complete ankylosis release, a jaw stretcher is applied to check the proximity of the bony cuts posteriorly during maximal mouth opening under general anesthesia during the surgical procedure and an adequate gap of 4–5 mm is maintained between the bony surfaces with this modified cut. Dermis fat is then interposed and placed in the space created, and the surgical site is sutured in layers.

Figure 3

Modified inferior osteotomy which prevents any contact between the surfaces even on maximal mouth opening

CONCLUSION

This modification creates more space posteriorly, which prevents contact between the posterior aspects of the osteotomized surfaces during maximal mouth opening. At the same time, it has no effect on decreasing the vertical ramus height. Thus, this simple modification was seen to significantly improve the treatment outcomes while re-establishing function satisfactorily and contributing to the prevention of reankylosis in all 37 of our patients.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.