Caso Clínico

Management of temporomandibular ankylosis during childhood by means of arthroplasty and soft tissue distraction
Tratamiento de anquilosis tempomandibular en la infancia mediante artroplastia y distracción
de tejidos blandos

M.A. Morey Mas¹, J. Caubet Biayna¹, J.I. Iriarte Ortabe¹, P. Quirós Alvarez², A. Pozo Porta², I. Forteza-Rey³

1 Médico Adjunto. Servicio de Cirugía Oral y Maxilofacial
2 Médico Residente. Servicio de Cirugía Oral y Maxilofacial
3 Jefe de Servicio. Servicio de Cirugía Oral y Maxilofacial
Hospital Universitario Son Dureta, Palma de Mallorca

Correspondencia:
Miguel Angel Morey Mas
C/ Alexandro (pintor), nº 6
07141 Marratxí (Baleares)
Email: mmorey@arrakis.es

Introduction

The changes that take place in the mandibular condyles during childhood can cause ankylosis and an alteration in the growth of the mandible. The most frequent causes of condylar damage are, among others, traumatic injury and infection.¹

The younger the patient with a condylar disorder, and the longer the delay in commencing treatment, greater will be the degree of facial deformity. This deformity will be different depending on if the condyle alteration is uni- or bilateral. Firstly, there will be limited oral opening and facial asymmetry consistent with mandibular hypoplasia of the affected side; the chin is retruding and deviated towards the affected side; the ipsilateral gonion angle is higher; on the occlusal plane there is an inclination of the lower incisors towards the healthy side, there is a cross bite on the affected side, and an inclination of the occlusal plane (canting). In the case of bilateral ankylosis, the posterior facial height is shortened, retrognathia appears and there is limited oral opening, together with a certain amount of shortening and hypertrophy of the masseter, pterygoid, temporal and suprahyoid muscles, due to isometric contractions.²

To date the best known treatment for ankylosis of the TMJ consists in resecting the ankylotic segment and fixing a costochondral graft with the aim of restoring facial height, making the deformity symmetrical and restoring oral opening. However, the growth potential of this graft is unpredictable, as intermaxillary fixation has to be carried out, and the donor site is not complication free.³

Over the last 15 years osteogenic distraction on a mandibular level has made a great contribution in the treatment of these patients, especially children.4 Technically, a resection of the ankylotic segment is performed together with and an osteotomy of the affected vertical branch; once the distraction vector has been checked, the distractor is placed and elongation is begun following a waiting period. In this way, mandibular symmetry is restored, occlusion is corrected and correct oral opening is achieved.^5,6,7,8

In the case we present, we have used a distraction technique in order to elongate soft tissues and maintain the space between the glenoid cavity and the neck of the resected condyle so as to avoid collapse and re-ankylosis, and to stimulate in the process the formation of a "neocondyle".

Clinical Study

We present the case of a nine-year-old girl from an African country that was sent to our Service through a charity. As a result of a fortuitous fall seven years previously, she had limited oral opening of 5 mm and a fracture in both condyles. On examination mandibular hypoplasia was observed with no symmetry, class II occlusion with compensation of upper and lower incisors, and deficient oral hygiene with caries (Fig. 1). An orthopantomography and a lateral teleradiography were made of the skull which showed bilateral temporomandibular ankylosis. The study was completed with a CT scan with 3D reconstruction (Fig. 2), photographs and evaluation by the Anaesthesiology Service. Orthodontic treatment was not possible due to the social background of the patient.

Surgical intervention was planned with the consent of her foster family. Nasotracheal intubation was carried out with a fiberscope. A preauricular approach was made exposing the ankylotic segment which was extensively resectioned and a new glenoid cavity was created. This was completed with a coronoidectomy with bilateral disinsertion of the temporal muscle. After confirming that there was an oral aperture of 30 mm, we placed an extra-oral Molina distractor in the zygomatic arch and in the ascending mandibular branch, with the aim of elongating the soft tissue and preventing reankylosis. The superficial, bloody areas of the resection were kept separate. The same intervention was performed on the contralateral joint. (Fig. 3 and 4).

Following a five-day waiting period, we started distraction of 1 mm a day and physiotherapy, which implied deactivating the distractor while exercises were performed. Distraction was completed on reaching class 1. During the "consolidation" period, the patient suffered a car accident which resulted in the right distractor becoming dislodged. This was put into place again with general anaesthetic and a laryngeal mask. The definitive removal of the distractors was carried out under local anaesthetic 11 weeks after surgery. There was a monthly follow-up of the patient following the removal of the distractors until she returned to her country 12 months after the intervention and maintaining an oral opening of 30 mm. (Fig. 5). A longterm follow-up has not been possible.

Discussion

Condylar changes produced during childhood can give rise to aesthetic and functional problems on a facial and speech level, with soft tissue repercussions. It is clear from this, that prompt treatment of ankylosis is beneficial, as the sequelae which originate during the growing stage, are minimized. In 1990 Kaban⁹ presented a protocol for ankylosis management associated with mandibular hypoplasia which consisted in the resection of the ankylotic segment, coronoidectomy and muscular disinsertion, interposition of the temporal fascia or cartilage, and reconstruction with a costochondral graft. This protocol, applied widely with modifications, has some disadvantages such as the need for intermaxillary fixation, morbidity of the donor site, possible blood transfusions and the unpredictable growth of the costochondral grafts. Other techniques such as sliding osteotomies of the mandible can only be performed once the growing period has finalized. Over the last decade, the application of distraction osteogenesis on the maxillofacial area has revolutionised the treatment of these patients, since it permits surgical intervention during the growth period. This has the advantage of minimizing later sequelae, it avoids psychological impact at a school age and an attempt is made to reduce morbidity.

It is known that deformity of the ankylotic patient is the result of the lack of growth of the condyle epiphysis and the lack of stimulation of the functional matrix according to Moss.¹⁰ Distraction has a beneficial effect on the condyle, stimulating it, increasing its size and redirecting it more favourably. In addition to this, according to the theory of the functional matrix, if the neuromuscular insertions are elongated, mandibular growth is achieved through positive stimulation, and this gradual elongation of the muscles, nerves, vessels and ligaments by means of distraction is of greater benefit than the rapid elongation which the placement of a graft implies, and the possibilities of a relapse are reduced.^11,12,13

Consequently, in our case, the use of distraction was designed to elongate soft tissues, especially the masticatory muscles, so as to maintain the space between the remaining condyle, following resection of the ankylosis, and the new glenoid cavity, with the aim of avoiding contact between bony surfaces which would lead to a predisposition for recurring ankylosis. In other words, the aim was in this case to release the "neocondyle" from the forces of compression, so as to stimulate later development in a growing patient.

On the other hand, there is controversy as to the use or not of interposition material so as to prevent re-ankylosis. Flaps and autogenous tissue grafts have been used (temporal muscle, masseter muscle, temporal fascia, skin, cartilage), heterologous grafts (for example, cryopreserved cartilage from Tissue Banks), xenografts (the use of bovine cartilage has been described) and alloplastic material (silicone, acrylic and teflon). We did not interpose any material basing ourselves on the consideration of some authors that if there is between 1,5 and 3 cm. between the base of the skull and the mandible, and if physiotherapy is begun quickly, there is no need to interpose any material.^14,15

Early physiotherapy is essential in these patients. The advantage that this technique offers, in comparison with those requiring intermaxillary fixation, is the possibility of starting rehabilitation exercises immediately after surgery.

Conclusion

In cases of ankylosis with little deformity the use of distraction with the aim of elongating soft tissue and maintaining the space created following arthroplasty, can constitute a good alternative due to the ease with which it can be performed and low morbidity.

References

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