Incremental increase in percentage mouth opening after coronoidectomy in temporomandibular joint ankylosis

Abstract

The aim of this study was to evaluate the incremental improvement in mouth opening following coronoidectomy. Twenty-three patients with unilateral temporomandibular joint (TMJ) ankylosis (Sawhney types I–III) were assessed preoperatively; physical and radiological examinations were done (panoramic radiography and computed tomography). Data including demographic and clinical parameters were recorded. Patients with bilateral ankylosis, recurrent cases, and those with Sawhney type IV TMJ ankylosis were not included. The improvement in mouth opening was measured after ostectomy, after ipsilateral coronoidectomy, and after contralateral coronoidectomy. The improvements in mouth opening at each stage were analysed using the Student’s t -test and Pearson’s correlation coefficient. There was a marked improvement in maximal incisal opening (MIO) from 5.7 ± 4.2 mm to 23.7 ± 5.9 mm after removal of the ankylotic bony mass. MIO was significantly increased after ipsilateral coronoidectomy (31.6 ± 7.4 mm), and after contralateral coronoidectomy, a mean MIO of 39.4 ± 11.2 mm was achieved. At more than 1 year of follow-up, all patients showed improved mouth opening. In conclusion, coronoidectomy plays an important role in improving mouth opening in the treatment of TMJ ankylosis.

The primary objectives of the treatment of temporomandibular joint (TMJ) ankylosis are the establishment of joint movement, prevention of relapse, and restoration of a harmonious occlusion and appearance to achieve normal growth and occlusion. Although attaining all of these goals is important, achieving adequate mouth opening for normal jaw function is considered to be the primary and most important goal, because most patients are more concerned about mouth opening.

In long-standing ankylosis, there is often difficulty in achieving adequate mouth opening even after removal of the ankylotic mass. While planning the treatment of TMJ ankylosis, the important anatomical consideration of an elongated coronoid process has to be kept in mind. Along with an elongated coronoid, there is often also hyperactivity of the temporalis muscle. All these factors have a role in inhibiting jaw movements. During mandibular opening, the coronoid process passes antero-inferiorly between the zygomatic arch and the lateral surface of the maxilla. If its pathway is impeded, it will not slide smoothly, which will result in difficulty in mouth opening. Hence, even after removal of the ankylotic mass, adequate mouth opening is sometimes not achieved. Generally, either the elongation of the process or an encroachment of fibrous tissue causes the coronoid impedence.

A few studies have assessed the role of coronoidectomy in the treatment of TMJ ankylosis. Kaban et al. suggested the role of ipsilateral and contralateral coronoidectomy after aggressive excision of the ankylotic mass. Kent et al., as well as Guralnick and Kaban recommended ipsilateral coronoidectomy to prevent inadequate intraoperative inter-incisal opening. Kaban et al. later recommended an ipsilateral coronoidectomy on the affected side and a contralateral coronoidectomy in the case of a maximal incisal opening (MIO) of less than 35 mm.

Although the coronoidectomy is employed frequently as a procedure to augment mouth opening after ostectomy, no quantitative evaluation of the incremental improvement in mouth opening associated with this procedure has been carried out to date, particularly in long-standing TMJ ankylosis.

This prospective investigational study was designed to evaluate the incremental improvement in mouth opening following coronoidectomy in the treatment of TMJ ankylosis.

Patients and methods

Study design

This was a prospective evaluation of the role of coronoidectomy in the management of TMJ ankylosis conducted in the department of oral and maxillofacial surgery of the study institution between February 2011 and September 2013. The study was designed in accordance with the principles of Good Clinical Practice (ICH-GCP) and the Declaration of Helsinki. All patients were supplied with an information sheet and provided written informed consent to participate in the study. Ethical approval was given by the local ethics committee.

Patient population

Twenty-three patients with unilateral TMJ ankylosis (Sawhney types I–III) were assessed preoperatively ( Table 1 ) ; patient history was recorded and physical and radiological examinations were done (panoramic radiography and computed tomography (CT)). Demographic and clinical parameters were recorded on a pre-prepared sheet and included the following: age, gender, aetiology and ankylosis type and duration, treatment performed, and pre- and postoperative MIO. Patients with bilateral ankylosis, recurrent cases, and those with Sawhney type IV TMJ ankylosis were not included in the study.

Table 1
Sawhney’s classification.
Type I The head of the condylar process is visible but significantly deformed, with the fibro-adhesions making TMJ movement impossible
Type II Consolidation of the deformed head of the condylar process and articular surface occurs mostly at the edges and in the anterior and posterior parts of the structures, and the medial part of the surface of the condylar head remains undamaged
Type III The ankylotic mass involves the mandibular ramus and zygomatic arch; an atrophic and displaced fragment of the anterior part of the condylar head is in a medial location
Type IV The TMJ is completely obliterated by a bony ankylotic mass growing between the mandibular ramus and cranial base

TMJ, temporomandibular joint.

Surgical procedure

Access to the ankylosed TMJ was accomplished using an Al-Kayat and Bramley or pre-auricular incision. After ostectomy, mouth opening was measured using a Vernier caliper or calibrated scale (stage I). An ipsilateral coronoidectomy was done using the same exposure. Mouth opening was measured again by the same assistant using the same scale to assess the improvement in mouth opening from the preceding step (stage II). A contralateral coronoidectomy, if required, was done through an intraoral approach. Again, mouth opening was measured using a Vernier caliper by the same assistant to assess the improvement in mouth opening over the preceding step (stage III). The joint was lined with a buccal fat pad or temporalis fascia. The ramus–condyle unit was reconstructed with a suitable graft if appropriate. The jaw was mobilized early in the postoperative period.

The procedures were planned in a step-wise fashion to achieve a mouth opening >35 mm, in accordance with the protocol of Kaban et al. The improvement in mouth opening was measured after ostectomy, after ipsilateral coronoidectomy, and after contralateral coronoidectomy.

Statistical analysis

Improvements in mouth opening at each step were analysed using the Student’s t -test and Pearson’s correlation coefficient. A P -value of < 0.05 was considered statistically significant. All statistical calculations were performed using SPSS software package version 17.0 (SPSS Inc., Chicago, IL, USA).

Follow-up

Mouth opening was assessed clinically and radiographically at 1, 3, and 6 months to detect any sign of recurrence. A CT scan was performed at the 6-month and >1-year follow-ups to detect any recurrence.

Results

Demographic and clinical parameters

The present study included 23 cases of unilateral TMJ ankylosis treated with surgery ( Table 2 ). The site of ankylosis was the left side in nine patients and the right side in 14 patients. Eight patients were male and 15 were female. The mean age of the study group was 19.7 ± 9.2 years, with a range of 8–45 years. The mean duration of ankylosis was 6.7 ± 7.1 years. No gross facial asymmetry was reported in any of the 23 patients.

Table 2
Demographic and clinical parameters of the study participants ( n = 23).
Patient Age, years Sex Site Ankylosis type Duration, years Preop. MO Stage I a MO Stage II a MO Stage III a MO Follow-up
6 months >1 year
1 34 M RT III 23 9 21 28 40 40 42
2 11 F LT III 5 13 23 33 41 41 44
3 8 M LT III 2 4 25 31 39 38 45
4 9 F RT III 1.5 14 33 38 40 46
5 35 F RT III 1 4 30 37 42 46
6 45 F RT III 33 0 20 30 35 35 36
7 15 F RT III 6 4 25 30 40 40 43
8 15 F LT III 5 4 2 30 40 40 44
9 17 F RT III 10 0 24 24 40 40 44
10 10 F RT III 1.5 0 34 38 40 39 45
11 15 F RT III 2 0 18 37 35 41
12 14 M LT II 2 0 25 30 38 39 44
13 17 F RT III 2 4 20 28 36 36 41
14 27 M LT III 6 5 18 25 35 35 38
15 14 F RT III 4.5 9 21 31 40 37 41
16 17 M LT II 5 8 23 33 41 42 46
17 18 F RT III 4 8 22 32 41 41 46
18 13 M RT III 5 9 26 30 39 39 42
19 22 M LT III 8 11 25 34 40 41 42
20 25 M RT III 6 10 26 32 41 40 43
21 23 F LT III 4 5 23 34 44 44 48
22 25 F RT III 6 3 21 33 40 40 43
23 26 F LT III 7 8 23 31 40 40 42
MO, mouth opening (in millimetres); M, male; F, female; RT, right; LT, left.

a See ‘Surgical procedure’ in the Patients and methods section for a description of the stages.

Clinical results

Considerable improvement in mandibular movement was noted in all patients. There was a marked improvement in MIO from 5.7 ± 4.2 mm to 23.7 ± 5.9 mm after removal of the ankylotic bony mass ( n = 23), with a mean percentage improvement in MIO of 76% ( Table 3 ). MIO was significantly increased after the ipsilateral coronoidectomy to 31.6 ± 7.4 mm, with a mean percentage improvement of 25%. When the MIO was less than 30 mm, a contralateral coronoidectomy was done. Following this, a mean MIO of 39.4 ± 11.2 mm was achieved, with a mean percentage improvement of 22%; this was not statistically significant as compared to the MIO after ipsilateral coronoidectomy.

Table 3
Mean difference in the percentage improvement from the preoperative measurement.
After ipsilateral coronoidectomy ( n = 23) After ipsilateral as well as contralateral coronoidectomy ( n = 20) a
Preoperative MO Ostectomy MO Ipsilateral MO Preoperative MO Ostectomy MO Ipsilateral MO Contralateral MO
5.7 ± 4.2 23.7 ± 5.9 31.6 ± 7.4 6.0 23.2 ± 5.2 30.8 ± 7.2 39.4 ± 11.2
Incremental percentage improvement 76% 25% 74% 25% 22%
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Jan 17, 2018 | Posted by in Oral and Maxillofacial Surgery | Comments Off on Incremental increase in percentage mouth opening after coronoidectomy in temporomandibular joint ankylosis
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