DISCUSIÓN

Chronic recurring dislocation. Treatment of muscular and bone components: Norman glenotemporal osteotomy

Luxación crónica recidivante. Tratamiento del componente óseo y muscular: osteotomía glenotemporal de Norman

Jacinto Fernández Sanromán

Jefe de Servicio. Servicio Cirugía Oral y Maxilofacial. Hospital POVISA, Vigo, España

Many treatments for recurring dislocation of the temporal mandible joint have been discussed. They include non surgical methods such as physiotherapy, occlusal splints, behavior modification, non convulsive medications or muscle relaxers; minimally invasive techniques: infiltration of intra or periarticular sclerosing substances, infiltration of toxins in the chewing muscles or injection of autologous intra articular blood. Many surgical techniques have also been published that deal with different articular components: increase or elimination of the articular eminence, reinforcement of the articular capsule and its ligaments, and elimination of the muscular traction of the lateral pterygoid muscles.

The existence of all of these procedures reflects the possible multifactor etiopathology of chronic dislocation: Looseness of the capsule and the ligaments, muscular stiffness, changes in the normal bone anatomy of the joint, or the presence of internal associated joint disorders (anterior disc shift, synovitis, bone arthrosis).

The majority of existing publications (like this article) discuss clinical studies that evaluate the efficiency of a treatment technique of this type. There are no prospective randomized studies that compare one technique to another. The majority of the ones that exist don't explain the articular pathology that treat, nor do they provide long term results. Reviewing the biography one could conclude that any of the techniques is adequate to treat this pathology. This conclusion probably isn't true.

Diagnosis of the cause or causes of recurring dislocation is what should guide us in our choice as to how to best treat the patient. Medical history (patient age, presence of ligament system pathology, neurological or muscular disorder), investigation (very loose joint, blocked mouth opening, joint noise), and an MRI (internal associated disorders, joint bone morphology) will allow us to evaluate which components of the TMJ and the chewing muscles should be treated.

The authors of this article do not show the results of the MRI taken before operating; because of this we don't know which cases had associated internal disorders. They only performed a meniscectomy and a meniscopexy in their series (in the rest of the cases were the discs situated normally?). There is no mention, in the materials and methods section or the results section, of how the clinical variables were measured (pain, noise, oral opening etc.) which makes it difficult to evaluate the results. The two patient groups with the highest frequency of recurring dislocation are older patients with neuropsychological disorders (dementia, spasticity) and young women with joint hyper mobility.

When conservative methods failed (control of spasticity, abnormal chewing movements, isometric oral closing exercises, infiltration of botulin toxin in select cases) perhaps the most commonly chosen surgical treatment in the first group of patients is bilateral eminectomy (Myrhaug H, 1951). This extra articular procedure ensures that the patient will not have more dislocation episodes; it is simple, predictable and has a fast recovery time.

Selecting a surgical technique for the second group of patients will depend on the etiopathogenic diagnosis and the coexistence of secondary internal joint disorders. In cases of joint hyper mobility caused by looseness with the eminence at a normal height (Fig. 1) perhaps the best procedure would be arthroscopy( being that it is a less invasive than arthrotomy) ( Merrill RG, 1992; Onishi M, 1989; Fernandez Samromán J, 2009) Several things can take place using arthroscopic control: the articular capsule can be retightened using radiofrequency devices (Fig. 2), infiltration of sclerosing substances in the posterior ligament or articular capsule (Fig. 3), treatment of internal disorders by repositioning the disc and reducing the traction of the lateral pterygoid muscle (Fig. 4), or by directly infiltrating with botulinum toxin (Fig. 5).

In exceptional cases where there is reduced height we can use either eminectomy (which alters the normal mechanics of the joint risking future internal disorders) or any technique that increases the height of the eminence or not repositioning the articular disc if it is previously displaced. The Norman technique with intervention of the cranial calvarium like the one described in 1997 (Fernandez Sanromán J, 1997) seems to be the more certain and predictable than collocation of bone synthetic materials that could cause future problems because of being subjected to constant load in young patients.

References

1. Myrhaug H. A new method of operation for habitual dislocation of the mandible: A review of former methods of treatments. Acta Odontol Scand 1951;9:247.        [ Links ]

2. Merrill RG. Mandibular dislocation, in Keith DA (ed): Surgery of the temporomandibular joint. Cambridge, MA, Blackwell Scientific 1992;170.        [ Links ]

3. Onishi M. Arthroscopic surgery for hypermobility and recurrent mandibular dislocation. Oral Maxillofac Surg Clin North Am 1989;1:153- 64.        [ Links ]

4. Fernández Sanromán J. Atlas de artroscopia de la ATM. Madrid, Ripano (En prensa).        [ Links ]

4. Fernández Sanromán J. Surgical treatment of recurrent mandibular dislocation by augmentation of the articular eminence with cranial bone. J Oral Maxillofac Surg 1997;55:333-8.        [ Links ]