Temporomandibular joint ankylosis fixation technique with ultra thin silicon sheet.

BACKGROUND: Temporomandibular joint ankylosis is a highly distressing condition in which the joint space is obliterated by scar tissue and the patient has an inability to open the mouth. Different autogenous and alloplastic interposition materials have been used after the resection of the ankylotic bone to achieve desirable and long lasting results. The recurrence of disease is most distressing for both patients and surgeon. We have been using ultra thin silicon sheet as our preferred material for providing proper fixation and cover to the joint. We have been encouraged by good patient compliance, no implant extrusion and favourable outcome.
MATERIALS AND METHODS: The clinical study included 80 patients with temporomandibular joint ankylosis, treated between April 2001 and March 2009. In all patients, temporomandibular joint ankylosis had resulted following trauma. Diagnosis was based on clinical assessment supplemented by radiographic examination consisting of a panoramic radiograph, axial and coronal computer tomography. The technique of using ultra thin silicon sheet covering whole of the joint space fixed with non-absorbable nylon 3-0 suture both medially to medial pterygoid muscle and laterally to periosteum of zygomatic arch was employed in all patients.
RESULTS: A total of 80 patients were in this study (59 males and 21 females). The aetiology of temporomandibular joint ankylosis was post-traumatic in all cases. The patients' age ranged from 5 to 45 years. The disease was unilateral in 61 cases and bilateral in 19 cases. Twelve patients, who had previous surgery done in the form of gap arthroplasty in 6 cases, costochondral graft in 4 cases and temporalis muscle in 2 cases, presented with recurrence on the same side. The pre-op inter-incisal mouth opening ranged from 4 to 12 mm. The intraoperative inter-incisal mouth opening ranged from 28 to 46 mm. An additional procedure was done in 13 patients, including placement of costochondral graft with coronoidectomy in 4 of these cases. There was no immediate complication and no incidence of facial nerve injury. There was no extrusion of the implant in immediate and follow-up period.
CONCLUSIONS: The use of alloplastic implants with less volume and proper fixation covering all the raw bone joint space prevents reunion of bone; fixation of the sheet prevents its movement and thus extrusion.

INTRODUCTION

The temporomandibular joint (TMJ) ankylosis occurs frequently due to mismanaged childhood oro-facial trauma and less commonly due to infection to the joint and its surrounding structures. This result in inability to open mouth, impairment of speech, poor oral hygiene, dental caries, periodontal diseases and even facial deformities.[1] The aim of treatment in TMJ ankylosis is not only to reestablish the movement at the joint but also to prevent it from relapsing again.[2]

The basic techniques for surgical correction of ankylosis include the following:

Gap arthroplasty (resection of the bony mass without interpositional material)

Joint reconstruction (resection of the bony mass with reconstruction by bone grafts or joint prosthesis)

Interpositional arthroplasty (resection of the bony mass with interposition of a biological material or non-biological material.[34]

The purpose of the study is to evaluate the use of ultra thin silicon sheet implant with proper fixation [Figures 1,2] as an effective interpositional material in the successful treatment of TMJ ankylosis.

Figure 1

Diagrammatic representation of fixation technique, Z Zygomaticarch, UTS Ultra thin silicon sheet, M mandible, SU Suture, MP Medial ptygeriod

Figure 2

Intraoperative view showing silicon sheet fixation, SU-Suture, UTS-Ultra thin silicon sheet, M-Mandible, MP-Medial ptygeriod

MATERIALS AND METHODS

Eighty patients suffering from TMJ ankylosis and admitted from April 2001 to March 2009 in the Department of Burns and Plastic Surgery, SMS Medical College and Hospitals, Jaipur were included in the study. All patients had the chief complaint of inability to open their mouth. Diagnosis was based on history and clinical assessment, supplemented with orthopantomogram (OPG) and computer tomographic scans [Figures 1–5]. Photographs were taken preoperatively, intraoperatively and postoperatively, and the interincisal jaw opening was measured before, during and after the arthroplasty.

Figure 5

Pre-op 3D CT reconstruction face showing right temporomandibular joint ankylosis

Pre-op right temporomandibular joint anklyosis

Pre-op CT showing right temporomandibular joint ankylosis

Operative procedure

All patients were operated under general anaesthesia with nasal endotracheal intubation. The TMJ release and reconstruction was done using a standard preauricular approach with temporal extension. The dissection was carried out through the superficial temporal fascia which was reflected anteriorly protecting facial nerve branches. The periosteum over the zygomatic arch was incised, followed by exposure of the ankylotic mass. After exposing the ankylosed joint, the bone was first cut at the lower end of zygomatic arch with the burr angled downwards under vision. Complete medial division was done by gentle tap from mallet and osteotome directed anteriorly and if mobility was not restored, then the anteromedial and posteromedial aspects were again looked at. Forceful opening was avoided until all bone connections had been divided.

A gap was made between the recountoured glenoid fossa and the mandible, and a thin silicon sheet with thickness of 2 mm and size of 5 cm by 5 cm was interposed into the joint space, anchoring it medially with non-absorbable 3-0 nylon suture to medial pterygoid muscle and laterally across the gap, covering the entire joint space, and was sutured to periosteum of zygomatic arch [Figures 1–2,6] to prevent any dislodgement. Costochondral graft was used where long bone block was removed especially in growing children and in recurrent cases, This was done to correct the shortening of height of ramus and an attempt was made to contour this to match the contour of the condyle. Both joints in bilateral ankylosis were operated at the same stage.

Figure 6

Intra-op showing silicon sheet fixation

The intraoperative mouth opening was measured, and after achieving haemostasis, the wound is closed with a suction drain. The drain was removed 48 hours posto-peratively and skin stitches were removed on the sixth post-operative day [Figure 7].

Figure 7

Post-op I week

All the patients were advised the follow-up protocol which was at monthly [Figure 8] intervals for 6 months, then every 3 months for the next 6 months and then annually [Figures 9–11]. During these follow-ups, the complaints of patients were noted and objective measurement of inter-incisal distance was done. Both active and passive physiotherapy were started in the post-operative period to achieve complete mouth opening from the sixth post-operative day and continued for at least 6 months.

Figure 8

Post-op 1 month

Figure 9

CT scan 2 years follow-up

Figure 11

2 years follow-up

3D CT reconstruction face 2 years follow-up

RESULTS

A total of 80 patients were part of the study (59 males and 21 females). All our patients were post traumatic - 43 due to fall, 34 had road traffic accident, and in the remaining 3, the cause was blow over chin leading to condylar fracture and subsequently ankylosis. Their age ranged from 5 to 45 years [Table 1]. The disease was unilateral in 61 cases and bilateral in 19 cases. The pre-op interincisal mouth opening ranged from 4 to 12 mm. The intra-operative interincisal mouth opening ranged from 28 to 46 mm. An additional procedure was done in 13 patients, including costochondral graft in 9 paediatric patients in whom a large ankylosed segment was removed, thus causing vertical shortening of mandible; coronoidectomy was added in 4 of these cases. There was growth of cotochondral graft with age. There was no immediate complication and no incidence of facial nerve injury. There was no extrusion of the implant in immediate and follow-up period. Nineteen patients were lost after the initial 2-year follow-up. There was no recurrence during the follow-up period ranging from 12 months to 9 years.

Table 1

Clinical details of patients

DISCUSSION

The normal mouth opening in adults (measured as the inter incisor distance) is between 40 and 56 mm. This distance in children varies, depending upon the age and stature of the child.

In post-traumatic ankylosis of TMJ, there is displacement or destruction of the meniscal cartilage.[5] As a result, there is bone to bone contact either directly or via blood clot which has a potential for osteogenesis, resulting in extensive fusion at the level of joint.[6]

Roychoudhury et al. have stated that in their series consisting of 50 cases of TMJ ankylosis, trauma was the aetiological factor in 86% of cases.[7] The aetiological factor in all cases in the present study was joint trauma.

The treatment of TMJ ankylosis continues to be a topic of current interest because of difficulties encountered in surgical techniques and a high incidence of recurrence. The fundamental aim in the treatment of TMJ ankylosis is the successful surgical resectioning of ankylotic bone, the prevention of recurrence, and aesthetic improvement by ensuring functional occlusion.[8] The techniques employed to that end are joint reconstructions performed with costochondral grafts or alloplastic joint prostheses, gap arthroplasty and interpositional arthroplasty.

At present, there is no ideal interpositional graft.[9] The problems encountered with the present grafts are: muscle shrinks and fibroses, fascia lacks bulk, cartilage tends to fibrose and calcify while alloplastic implants under functional loads disintegrate and cause foreign body giant cell reactions.[9-12] Although temporalis flaps are still the most popular choice of grafts, dissecting temporalis muscle leads to scar contracture of the donor site which may further exacerbate the trismus unless an ipsilateral coronoidectomy is performed.[1013] The use of autogenous full thickness skin or dermis grafts as interpositional materials has also been published.[14]

The advantages of the alloplastic material are: they are easy to use, have a short operating time and low cost; however, the disadvantages are foreign body reaction, dislodgement, and infection. Usually, silicone is used as a rectangle or a disc, but these must be rigidly fixed. In spite of this, dislodgement or extrusion may occur. It is recommended that the TMJ ankylosis should be dealt with aggressive surgical approach with minimal resection of bone in vertical height and using silastic interpositional material followed by early mobilisation of the joint. It not only results in satisfactory mouth opening and jaw function, but also ensures in reduction of subsequent re-ankylosis.

Using silicone implants as inverted T-shaped implants to decrease the complication rate was proposed by Karaca et al. and the long-term results were perfect.[1516]

In our study, we had used ultra thin silicon sheet of thickness of 2 mm replicating the normal intra-articular disc, which was fixed with sutures so as to completely cover the joint space thus preventing any contact between raw areas. The fixation of the sheet reduces the chances of re-ankylosis due to displacement or extrusion of the implant. We did not come across any case of loss of implant by either extrusion or displacement. Thus, there is no recurrence in this study.

CONCLUSIONS

This method of providing fixation to the ultra thin silicon sheet implant can be used confidently in all cases of ankylosis. It was used in 80 patients and no dislocation or extrusion of the implant was observed. There also was no re-ankylosis of the TMJ. We conclude that the use of ultra thin silicon sheet with less volume and proper fixation, covering all the raw bone joint space, prevents reunion of bone; fixation of the sheet prevents its movement and thus extrusion.