Controversias en Cirugía Oral y Maxilofacial: Parte I

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Subcondylar osteotomy in the treatment of mandibular deformites
Osteotomía subcondílea en el tratamiento de las deformidades mandibulares

 

J. Alonso del Hoyo 

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Abstract: The surgical correction of prognathism by interventions in the ascending branches of the mandible was the option that substituted the «ostectomy» techniques that reduced the mandibular volume or, more exactly, the length of the body bilaterally. Subcondylar oblique osteomies are performed above Spix's spine, preserving the vascular-nervous package, that comes from the signoid notch, reaching the posterior border of the jaw. Since the year 1974, we have used the subcondyar oblique technique (SOO) intraorally in 367 cases for the correction of prognathism.

Resumen: La corrección quirúrgica del prognatismo mediante intervenciones en las ramas ascendentes de la mandíbula, fue la opción que sustituyó a las técnicas de ostectomías que reducían el volumen mandibular o más exactamente la longitud del cuerpo bilateralmente. Se realizan osteotomías subcondíleas oblícuas por encima de la espina de Spix, preservando el paquete vásculo-nervioso que, partiendo de la escotadura sigmoidea, llegan al borde posterior de la mandíbula. Desde el año 1974 hemos empleado la técnica subcondílea oblicua (OSO) por vía intraoral en 367 casos para la corrección del prognatismo.

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 Profesor Titular de Universidad. Cirugía Oral y Maxilofacial. Madrid. España

Correspondencia: 
J. Alonso del Hoyo 
c/ O´Donell 30 
28009 Madrid, España. 

 

Introduction

The surgical correction of prognathism by interventions in the ascending branches of the mandible was the option that substituted the «ostectomy» techniques that reduced the mandibular volume or, more exactly, the length of the body bilaterally. Although from an esthetics point of view they fulfilled a substantial objective in many cases, they have disadvantages in regards to access route (external) and lingual functionality: reduction of the space for its lodging, maintaining its posterior anchorage.

The «sliding» osteotomies have mostly obviated these disadvantages, although the depressor muscles could sometimes act negatively on the results, causing open bites. 

The sagittal technique of Obwegeser-Dal Pont,¹ made up an important advance and was accepted as ideal in the U.S.A. first (1963) and later in the rest of the world. 

The relative surgical difficulty of this technique is compensated by the possibility of performing it intraorally, which would make it possible for oral surgeons who could not access it externally to carry it out. 

Previously, in 1957, Hinds and Robinson² described the subcondylar technique to retrude the prognathic mandible.

Subcondylar oblique osteomies are performed above Spix's spine, preserving the vascular-nervous package, that comes from the signoid notch, reaching the posterior border of the jaw. The Caldwell's and Letterman's osteotomies (1954),³ initiated in the mandibular border and ascended towards the sigmoid notch. 

Both techniques are described by their authors with external approach: perauricular and submandibulara respectively. This means a disadvantage versus the sagittal technique to which the possible injury of the auditory nerve must be added. 

After, intraoral appro-aches were tested with success and have been maintained up to now. 

Material and method 

Since the year 1974, we have used the subcondyar oblique technique (SOO) intraorally in 367 cases for the correction of prognathism:

• SOO Exclusively 98. 

• SOO Combined with other osteotomies 270.

From the research point of view, we must cite the two doctorate thesis performed by our collaborators that verify most our preference for the subcondylar oblique osteotomy (SOO). 

The first one was done by Dr. F. Monje Gil in l992 on the Influence of ortognathic surgery in the temporomandibular joint (TMJ).⁴ The investigation was carried out in 289 rats, of which 60 were done as bilateral SOO. Good response to the surgery in the adaptation of the TMJ could be demonstrated after a remodeling period of the joint. 

In the thesis of Dr. J. Fernández Sanromán, «Influencia de la Cirugía Ortognática en la ATM» (Influence of Ortognathic Surgery in TMJ),⁵ the surgical response of the TMJ in 35 patients operated on with SOO between 1990 and 1993 was analyzed. The study was carried out from the clinical point of view and with different imaging technique. It was also demonstrated that the articular physiology recovered favorably after a slow adaptation period. 

In our opinion, the intraoral Hinds technique is the most adequate for the correction of prognathism and we have used it since 1974. 

In the year 1977, we introduced a variant in the Hinds technique.⁶ It consists in performing the osteotomy in two lines: one horizontal from the posterior border above Spix's spine and the other oblique which, leaving the notch that is going to come together with the first line in its anterior end. In this way, the proximal fragment is not triangular but rather trapezoidal (see figure 1 to 4). The reason for this change was that with the original technique, the mesial fragment -that reached the posterior mandibular border from the signoid notch- presented two disadvantages in our opinion: certain difficult to evade the entry of the v.m. package in some cases and also the fragment was very narrow in its inferior end and could cause a distal necrosis. The horizontal line of our osteotomy eliminates both things. (Figs. 1 to 5)

Discussion

Before having the data that the theses mentioned gave us, we believed that the SOO was more beneficial for the TMJ than the sagittal technique, as it permitted freedom to the condyle to adopt the most adequate «comfortable» position within the articular cavity. 

There is another very interesting fact that supports the choice of the SOO and it is that the consideration of the facture callus does not end until after at least three months. This means that during a long post-operative period, the callus is «soft» and «malleable» to a certaidegree. This favors the fact that the condyle adopts the most comfortable relationship with the glenoid cavity. Rigid fixation in the sagittal technique makes it necessary to place the condyle in «centric» position and this is not easy in a chemically relaxed patients and in the supine decubitus position. 

The incision for the SOO differs little from that corresponding to that of the sagittal technique, although it is somewhat more prolonged in its superior end. It also requires special retractors and it is true that the visibility is somewhat limited for the sigmoid osteotomy. However, in the cases in which the ramus has little thickness, there is danger of fracture and injury of the vascular-nervous package with the sagittal technique when separating the fragments. With the subcondylar oblique technique, these two situations are avoided since the thinness of the ramus is not a disadvantage and it is not possible to injure the teeth if the osteotomy line passes behind its entry in the ramus. We have not maintained an intermaxillary fixation of 40 days for some time. We perform an elastic fixation in the surgery room and begin with an opening at 10 or 12 days that makes a very soft diet possible. After, the elastic fixation are removed to eat and to maintain little tension day and night. With it, the condyle accommodation will be slowly directed and facilitated. The criterion is similar to that followed in condyle fractures. In them, an early directed mobilization is also established to maintain symmetry. 

The danger of relapse in the SOO is less when the condyle is not required to adopt a forced position and we have verified this in our cases. The defenders of the Osbwegeser technique maintain the important advantage of the fact that the patient does not require intermaxillary fixation in the postoperative period. Theoretically this is true, however the truth is that there is opening limitation for eight or ten days. In any event, is the possibility of opening the mouth early more desirable than achieving a balance in the TMJ? In the combined osteotomies -upper maxillary and mandible- we have also found advantages with the SOO, verifying a favorable relocation of the condyles and absence of articular pathology. 

Advantages of subcondylar oblique osteotomy (SOO) 

A. The technique is relatively easier, if a good surgical field is achieved. 
B. It is a faster operation (45-50 minutes each side). 
C. It does not require any osteosynthesis. 
D. The condylar fragment remains free and on the external ramus face. 
E. It is not necessary to achieve the centric position of the condyle. 
F. The intermaxillary fixation is only maintained 10 or 12 days. 

Conclusions 

We consider that the SOO is the most adequate for the treatment of prognathism to gather esthetic and functional advantages and minimize relapses. 

Nowadays, different schools in the world share this opinion. From the onset, we have referred to surgical treatment of prognathism, not retrognathism. 

There is no doubt that in these cases, the SOO is not indicated and the sagittal osteotomy, inverted L, distraction, etc., must be used.

References

1. Obwegeser HL. The indications for surgical correction of mandibular deformity by the sagittal splitting technique. Br J Oral Surg 1963;1:157        [ Links ]

2. Hinds EC. Surgical correction of mandibular deformities. Am J Orthodont 1957;43:171-3.         [ Links ]

3. Caldwell JB, Letterman GS. Vertical osteotomy in the mandibular rami for the correction of prognathism. Oral Surg 1954;12:185-202.         [ Links ]

4. Monje F. Influencia de los factores extra articulares sobre la ATM Estudio experimental en ratas. Tesis doctoral. L. 992.         [ Links ]

5. Fernández Sanromán J. Influencia de la cirugía ortognática en la articulación temporomandibular. Estudio prospectivo clínico y por imagen. Tesis doctoral 1995.         [ Links ]

6. Alonso del Hoyo J. Plan de tratamiento ortodóncico-quirúrgico en las deformidades maxilofaciales. XVI Congreso de la SEDO. Palma de Mallorca. Junio 1980.         [ Links ]