Posted in TMJ Disorders

Condylar Fractures

Introduction

The management of mandibular condylar injuries is one of the most controversial areas in the treatment of facial trauma. Fractures involving the mandibular condyle are the only facial bone fractures which involve a synovial joint. These injuries deserve special consideration apart from those of the rest of the mandible due to their anatomic differences, variations in clinical picture, unique management protocols and distinct healing potential.

Epidemiology

The incidence of fracture involving the mandibular condyle varies throughout the literature and is influenced by factors such as age, geographic location and socio-economic level of the study population. Serial studies by Kromer (1953) and Goldberg and Williams (1969) found that fractures of the condyles account for 15% to 30% of all mandibular fractures. Halazonetis (1968) and Ellis et al (1985) reported that condyle is the commonest site for mandibular fracture. Oikarinen and Malmstrom (1969), in a series of 600 mandibular fractures, found that 33.4% were in the subcondylar region. The incidence reported by certain other series are 27.7% (Elkholm, 1961), 25% (Schuchardt and Metz, 1966), 35.6% (Rowe and Killey, 1968), 32.4% (Tasanan et al, 1975), 37% (Larsen and Nielson, 1976), 47% (Van Hoof et al, 1977), 52.4% (Olson et al, 1982), 49% (Hill et al, 1984), 40% (Andersson et al, 1984), 29% (Ellis et al, 1985), 21% (Haug et al, 1990), 52.4% (Silvennoinen et al, 1992) etc.


Aetiology of condylar injuries

Facial injuries are most commonly associated with falls, motor vehicle accidents, sports-related trauma and interpersonal violence. Injury to the condyle may be caused by a variety of mechanisms, which also vary according to the characteristics of the group studied.

In adults, motor vehicle accidents account for the majority of condylar fractures, while interpersonal violence, work-related incidents, sporting accidents and falls play significant but lesser roles. In children, falls and bicycle accidents are the major causes, with motor vehicle accidents also contributing significantly. Different still are the elderly, in whom falls again constitute the primary aetiologic factor, followed by assaults and automobile accidents. Other less obvious causes of injury to the TMJ include orotracheal intubation, whiplash injury, childbirth and weight lifting.

Mechanism of condylar fractures

The condyle is a link in the direct continuity of the mandible from glenoid fossa of one side to the other. This has the effect that a fractured condyle can occur indirectly as a result of a blow to some other part of the mandible (contre-coup injury).

Factors that are considered important in determining the type of fracture and the degree of displacement are the nature, severity and direction of the traumatic force, the occlusion of the teeth and the position of mandible on impact, and anatomic considerations like the line of fracture and the influence of muscle pull, ligaments and the adjacent soft tissue.

The traumatic force

Studies of the relation between are the nature, severity and direction of the traumatic force on the resultant mandibular injury were made by Huelke (1961, 1962, 1964, 1968). Huelke and Harger (1969) found that greater than 75% of all experimentally produced fractures of the mandible were in primary areas tensile strain. Lindahl (1977) divided trauma causing condylar injury into three main groups.

  1. Kinetic energy imparted by a moving object through the tissues of a static individual. This commonly results from trauma sustained from a fist, during sporting activities, or in some industrial accidents.
  2. Kinetic energy derived from the movement of the individual and expended upon a static object example is fall during an epileptic fit or following a faint when the patient is unable to protect the face with an outstretched hand as in the case of the so called ‘parade-ground’ fracture.
  3. Kinetic energy which is summation of force derived from combination of 1 + 2 and generally produces a severe type of injury such as typically occurs in road traffic accident.

In addition to these forces, minor trauma (e.g. a yawn or pressure during dental treatment) may cause subluxation or even dislocation in those individuals who exhibit excessive laxity of the joint capsule.

In response to loading, the mandible is similar to an arch because it distributes the force of impact throughout its length. But it is not smooth curve of uniform bone, and contains discontinuities such as foramina, sharp bends, ridges and regions of reduced cross-sectional dimension like the subcondylar area. As a result, parts of the mandible develop greater force per unit area, and thus tensile strain is concentrated in these locations.

When a force is directed along the parasymphysis-body region of the mandible, compressive strain develops along the buccal aspect, and tensile strain along the lingual aspect. This produces a fracture that begins in the lingual surface and propagates towards the buccal surface. The mobile contralateral condyle moves in a direction away from the impact point until it is limited by the bony fossa and associated soft tissue. At this point, tension develops along the lateral aspect of the contralateral condylar neck, and a fracture develops. If greater force is applied to the parasymphysis-body region, the continued medial movement of the smaller ipsilateral mandibular segment will lead to bending and tension forces along the lateral aspect, and subsequent fracture of the ipsilateral condyle also.

Force applied directly in the symphysis region along an axial plane is distributed along the arch of the mandible. Because the condylar heads are free to rotate within the glenoid fossa to a certain degree, tension develops along the lateral aspect of the condylar neck and mandibular body regions, as well as along the lingual aspect of the symphysis. This leads to bilateral condylar fractures and a symphyseal fracture.

The connection between whiplash injury (cervical extension-flexion) and internal derangement of the TMJ was discussed by Roydhouse in 1973. This may be due to the stretching and tearing of the posterior and polar attachments of the disc in the cervical hyperextension phase. This typically happens in rear-end collisions when an unsupported head accelerates less quickly than the body with downward and forward displacements of the disc-condyle complex. Then, as the vehicle decelerates by braking or hitting other objects, there is a crushing impact of the already traumatised posterior attachment. Weinberg and Lapionte (1987) found TMJ internal derangement in 88% of their patients with whiplash injury. The importance of recognition of this connection and early therapeutic intervention were stressed by Manheimer et al in 1989.

Occlusion and mandibular position

Early observers felt that the presence of posterior dentition tended to reduce the incidence of condylar injury. The implication was that, as the mandible was forced superiorly and posteriorly, the dentition would meet and absorb some of the force, thereby diminishing the force received at the condyle. More recent findings show that all types of fractures occur irrespective of the dentition and occlusion. However, the presence of impacted third molars has been shown to markedly reduce the incidence of condylar fractures. The area of impacted tooth represents an area of inherent weakness, thus increasing the chance of fracture in that area and reducing the chance of condylar fractures.

The relative degree of mandibular opening at the time of impact plays an important role in the type of fracture that occurs. More recent investigations have shown that even the level of fracture varies with the degree of mouth opening. When the mouth is opened, the fracture tends to be more in the condylar neck or head region, whereas when it is closed, the fractures are in the subcondylar area.

Muscle pull

Once a fracture occurs, the associated soft tissues, particularly the muscles of mastication attached to the bony segments, determine the direction and degree of displacement or dislocation. Typically the fractured segments tend to override each other as a result of the powerful pull of the masseter, medial pterygoid and temporalis muscles. If the fracture line occurs below the attachment of the lateral pterygoid, which is most common, the medial, inferior and anterior pull of this muscle tends to displace the condylar head in that direction. This medial and anterior pull is directed towards the weakest area in the TMJ capsule, which is why antero-medial displacement and dislocation are the common patterns.


Classifications

Classically, fractures have been classified according to their location on the condyle or its neck, and the relation of the proximal segment to the glenoid fossa. Though the condylar fractures are generally classified as extracapsular, subcondylar and intracapsular, various authors have proposed many classifications down the years.

Wassmund (1934) described five types of condylar fractures.

Type I- fracture of the neck of the condyle with relatively slight displacement of the head. The angle between the head and the long axis of the ramus varies from 10 to 45 degrees. According to Wassmund, these fractures tend to reduce spontaneously.

Type II- fractures which produce an angle of 45 to 90 degrees, resulting in tearing of the medial portion of the capsule.

Type III- the fragments are not in contact, and the head is displaced mesially and forward owing to traction of the lateral pterygoid muscle. The fragments are generally confined to within the glenoid fossa. The capsule is torn, and the head is outside the capsule. Wassmund recommended an open reduction for this type of fractures.

Type IV- fractures where the condylar head articulates in an anterior position to the articular eminence.

Type V- vertical or oblique fractures through the head of the condyle. Wassmund suggested a bone graft to reconstitute the condylar head when considerable displacement of the fragments has occurred.

Other classifications of historical importance include those of Thoma (1958), Köhler (1951), Dingman and Natwig (1964), Rowe and Killey (1969), Reichenbach (1969) etc.

MacLennan (1952) evolved a clinical classification mainly based on the relationship of the fractured condyle to the remainder of the mandible.

Type I                        Non-displaced fracture

Type II                      Fracture deviation, where there is simple angulation of the condylar process to the major fragment. (e.g. greenstick fracture)

Type III                    Fracture displacement, where there is simple overlap of the condylar process and major mandibular fragments.

Type IV                      Fracture dislocation, where the head of the condyle is completely disrupted from the articular fossa.

Spiessl and Schroll (1972) suggested a simple classification listing the common sites and types of displacement.

  1. non-displaced fracture
  2. low-neck fracture with displacement, mostly with contact between fragments
  3. high-neck fracture with displacement, mostly without contact between fragments
  4. low-neck fracture with dislocation
  5. high-neck fracture with dislocation
  6. intracapsular fracture of condylar head

Lindahl in 1977 proposed a classification based on radiographic views in two planes at right angles to each other. He took into consideration three major aspects. They are the anatomic location of the fracture, relationship of condylar fragment to mandible and relationship of condylar head to the glenoid fossa.

  1. Anatomic location of the fracture
  2. Condylar head
  3. Condylar neck
  • Subcondylar
  1. Relationship of condylar fragment to mandible
  2. Nondisplaced
  3. Deviated
  • Displacement with medial or lateral overlap
  1. Displacement with anterior or posterior overlap
  2. No contact between fractured segments
  3. Relationship of condylar head to fossa
  4. Nondisplaced
  5. Displacement
  • Dislocation

Helmut Schüle in 1986 gave an exhaustive list of the types of injuries to the TMJ region

1.1.1      Contusion of the TMJ

  • Fractures of the condylar process without displacement of the fragments
    • Fractures of the condyle

Transcapitular.

Subcapitular.

  • Fractures of the condylar neck
  • Basal fracture of the condylar process.
  • Fractures of the condylar process with displacement of the fragments.

Displacement of the small fragments.

Ventrally.

Dorsally.

Medially.

Laterally.

Torsion of fragments

Displacement with contraction

Compression fracture of the condyle.

  • Sprains of the TMJ
  • Dislocation (subluxation) of the TMJ.

Dislocation of the condylar head (condyle).

Anteriorly.

Posteriorly

Cranially (central dislocation).

Medially

Laterally.

  • Fracture dislocations of the condylar process.

Dislocation of the condylar head (condyle).

Anteriorly

Medially

Laterally

Dorsally.

Injuries of the TMJ other than fractures

Although the most commonly documented result of trauma to the TMJ and condyles is fracture, other injuries occur as well, and must be considered in the differential diagnosis.

Contusion

Contusion of the TMJ refers to the consequences of blunt trauma to the joint region that is injurious but has not resulted in fracture or in tearing of the capsule.

Effusion and haemarthrosis

Like any other joint, the TMJ reacts to trauma with serous or haemorrhagic effusion. This often leads to distension of the joint capsule with varying amounts of discomfort. Frequently, deviation of the mandible away from the affected side occurs as a result of downward pressure on the condyle from the production of fluid within the joint. This produces facial asymmetry and malocclusion.

Rupture of minor blood vessels in the joint might cause a pooling of blood in the joint space. This condition, called haemarthrosis, presents with features similar to a simple effusion, but is more dangerous since it is thought to predispose to serious complications like infection or joint ankylosis.

Intracapsular soft tissue injury

Very often, a blunt trauma can lead to damage of the articular disk, articular cartilage or both. The joint typically responds with a serous effusion and/or muscle spasm. As the case may be, joint presents with a clinical deviation of the mandible and severe pain.

TMJ sprain

Sprain refers to strain of the ligaments and capsule of the joint with microscopic or macroscopic lacerations but without permanent change in the position of the condyle. Secondary phenomena are serous effusion or haemarthrosis. Sprains differ from dysfuncional arthropathy and habitual subluxation in that they are produced from by the action of a force which produces acute injury.

Subluxation

The term subluxation implies the displacement of the condylar head from the glenoid fossa, which the patient can reduce himself. This is usually the result of excessive laxity of the joint capsule coupled with varying degrees of continuous or intermittent trauma.

Dislocation

A dislocation is considered to be present if the condylar head is expelled from the glenoid fossa and remains fixed there. The condyle is often dislocated and fixed without laceration of the relatively flaccid capsule. The condition may be unilateral or bilateral. When this is associated with a fracture of the condyle, it is termed a ‘fracture-dislocation’. Dislocations can occur anteriorly, posteriorly, laterally and superiorly.

Anterior dislocation (Heslop, 1956)

Anterior dislocation occurs when the condyle moves anterior to the articular eminence. This is the most frequently seen condition, and it represents a pathologic forward extension of the normal translational movement of the condylar head. This may be caused by yawning, oral sex, phenothiazine use, and trauma. Traumatically induced anterior dislocations are usually bilateral, but it may occur unilaterally as well. Diagnosis is made by these features: an anterior open bite with inability to close the mouth, severe pain in the region anterior to the ear, absence of the condyle from the pre-auricular fossa with a pre-auricular depression, inability to move the mandible except slight opening, difficulty in speaking and a prognathic appearing lower jaw. An antero-lateral variant is described by Monis and Hutton (1957).

Posterior dislocation (Helmy, 1957)

This implies a coexistent fracture of the base of the skull or the anterior wall of the bony meatus.

Superior (Central) dislocation (Zechal, 1977)

Superior dislocation into the middle cranial fossa must be associated with a fracture of the glenoid fossa. The medial and lateral elevated margins of the fossa normally meet the articular surface of the condyle on impact, thus protecting the central weak area of the fossa and this injury is probably most often related to a small bounded condyle which fails to impinge on the margins.

Lateral dislocation (Allen and Young, 1969)

These authors describe two subgroups

Type I which is lateral subluxation

Type II a complete subluxation, where the condyle is forced laterally and then superiorly to enter the temporal fossa. An essential prerequisite for lateral displacement is a fracture of the body of mandible that occurs near the symphysis.

It should be emphasised that all the groups other than anterior dislocation are very rare.

 


Diagnosis of condylar injuries

Diagnosis is based on a suggestive history, determination of the direction of force, clinical signs and symptoms and radiographic visualisation of the joint and subcondylar region.

Clinical features

An overall evaluation of the patient with traumatic injury should precede evaluation of the maxillofacial region. Numerous symptoms point generally to traumatic damage in the joint region. They include pain, tenderness and swelling in the joint region, limitation of mouth opening and malocclusion. Supplementing these suggestive symptoms, different fracture types provide characteristic symptoms.

The deviation of mandibular path at rest or on attempts to open the mouth gives vital clues on the type of injury to the joint. A post-traumatic effusion or haemarthrosis may distract the joint surfaces, causing posterior open bite on the affected side with deviation of the mandibular midline to the opposite side. In unilateral dislocation without fracture, the mandibular midline is deviated to the contralateral side with inability to occlude being more pronounced on the affected side. Bilateral dislocation without fracture is likely to produce an appearance of prognathism with almost complete inability to occlude any teeth.

Three rare varieties of dislocations give characteristic findings

  1. Central dislocation through the glenoid fossa, without fracture of the condylar neck, produces deviation of the mandibular midline to the ipsilateral side, gagging of the ipsilateral posterior teeth, contralateral posterior open bite and absolute immobility which persists even under general anaesthesia.
  2. Lateral dislocation of the condylar head into the temporal fossa, where it would be palpable, is associated with a marked crossbite on the affected side. There will also be signs of associated fracture in some site in the anterior part of the mandible.
  3. Worthington in 1982 described a case of extreme antero-superior dislocation without fracture in which the condyle was displaced into the temporal fossa.

Apart from a suggestive history, the patient with fracture of mandibular condyle presents with these symptoms.

  1. Evidence of trauma, which may include facial contusions, abrasions, laceration of the chin and ecchymosis and/or haematoma in the TMJ region. These injuries should alert the clinician not only to possible fractures in the area of direct injury but also indirect injury to the ipsilateral as well as the contralateral TMJ.
  2. Bleeding from the external auditory canal, which may indicate fracture of anterior tympanic plate from a posteriorly displaced condyle.
  3. Visually noticeable or palpable swelling over the TMJ. This may be due to haematoma or oedema or may be secondary to a laterally displaced condylar head, which may be directly visible under the skin.
  4. Facial asymmetry as a result of soft tissue oedema or due to foreshortening of the ramus caused by overlap of proximal and distal fracture segments.
  5. Pain and tenderness to palpation of the affected joint. There may also be significant pain on attempted manipulation of the jaw by the patient or by the clinician.
  6. Crepitation over the affected joint secondary to friction of the irregular fracture ends sliding over one another during manipulation.
  7. Malocclusion, the type of which depends on the type of injury sustained. A unilateral condylar fracture usually results in ipsilateral premature contact of the posterior dentition on that side. This foreshortening may also result in contralateral posterior open bite due to the canting of the mandible. Bilateral condylar fractures may result in a marked anterior open bite and retrognathia. The medial pterygoid and masseter muscles exert a superior and posterior pull on the distal mandibular segment, causing it to telescope past the condylar segments. This telescoping results in premature contact of the posterior occlusion with rotation of the mandible around this point, and anterior open bite. Gagging of the posterior occlusion may also occasionally be seen because of the posteriorly positioned mandibular segment.
  8. Deviation of the mandibular midline may be seen both at rest and with attempted excursion of the mandible. At rest, this is because of the shortening of the ipsilateral ramus, causing the mandible to deviate towards the fracture side. In a unilateral fracture, with attempted opening of the mouth, the lateral pterygoid on the fracture side is unable to effect pull on the mandible, while the unaffected contralateral muscle functions normally. This inequality of function causes an exaggeration of the deviation towards the fractured side. Similar deviation is seen with protrusive movements. Attempts to move the mandible laterally away from the fractured side are met with great difficulty and discomfort because of the ineffective lateral pterygoid muscle. Bilateral condylar fractures may result in little deviation because both condyles are involved. As mentioned, an anterior open bite will be seen with retrognathia in addition to a severely limited range of motion.
  9. Muscle spasm (splinting) with associated pain and limited opening.
  10. Associated fractures (dento-alveolar / symphyseal / body of the mandible / angle / zygomatic complex regions)

Radiography

A variety of imaging methods is available to assist in accurate diagnosis and localisation of condylar injuries. The imaging techniques allow visualisation of the internal structures of the joint and the actual position of the fractured segments, and help in arriving at a proper treatment plan based on an accurate diagnosis. This usually requires at least two radiographs to be obtained, at right angles to each other.

Conventional radiography

The conventional radiographic techniques available to view the condylar region include

  1. Orthopantomogram (OPG)

The panoramic radiography gives the overall relationship of the proximal and distal fragments. The typical findings of condylar fractures visible on OPGs are a shortened condylar-ramus length, the presence of radiolucent fracture line or, in the case of overlapped segments, presence of a radio-opaque double density. A high OPG centred on the condyles in the mouth open position (if possible) would be of good help in visualisation of the condyle.

Chayra et al (1986) found that when compared to the standard mandibular series, the OPG has a higher accuracy in detecting all types of mandibular fractures. They site decreased cost, as well as lower radiation exposure, as advantages of the panoramic view. However, it requires the patient to be able to stand erect and immobile for an adequate period of time.

  1. Lateral oblique view of mandible

This is the radiographic view classically used for visualising the condylar region. This is still applicable if OPG facilities are not available; a view centred on the vertical ramus should be asked for. Displacements in the antero-posterior plane are well visualised in this radiograph.

  1. PA view of mandible

The postero-anterior (PA) or antero-posterior (AP) views have been traditionally used to view the subcondylar region and to detect lateral or medial displacements of the condylar head. This technique gives a good representation of the proximal and distal fragments in a medio-lateral plane. In most cases, the mastoid process overlaps the condylar region and the joint proper may not be adequately visualised.

  1. Reverse Towne’s view

The classical Towne’s (AP with 30° deviation) and the reverse Towne’s view (PA with 30° deviation) have been used to circumvent the overlapping of adjoining bony structures. These techniques show the condylar heads better than the conventional PA or AP, without superimposition on the image of the base of the skull.

The technique of modified Towne’s view, directing the X-ray beam superiorly an additional 5° may be used to further project the condyles below the mastoid process. The modified Towne’s view shows the degree of medial and lateral displacement of the fracture and allows for the visualisation of subtle deviation, such as seen in green-stick fractures that are not readily evident on panoramic view.

  1. Transcranial views for TMJ

These coned down views may be helpful in defining the relationship of the proximal condylar fragment to the glenoid fossa, and also in delineating the pattern of high (intracapsular) fractures. A lateral-oblique transcranial view is found to be the optimal technique for this purpose.

Tomography

Conventional tomography, either in coronal or sagittal planes could be made use of in cases where conventional radiographs have not been definitive or are not possible due to associated injuries. The advantage of this method is that it can be used without turning the face of the patient downward or other manipulations which may be difficult in an injured patient. It is often available at a lesser cost than CT scanning or MRI.

CT Scan

Computed tomography (CT) scans yield excellent bony detail of the facial skeleton in multiple views and, with adjustment of the contrast of the machine, give adequate soft tissue detail. It shows the relationship of the condyle to the fossa more precisely than conventional radiographs. It also better demonstrates fine bony alterations at the fracture site together with the direction of displacement of the fractured condyle in any plane. To a lesser extent, it can demonstrate changes in the position and function of the disc. Another advantage of CT scanning is the less dependence on patient co-operation, which is useful in severely injured or uncooperative patient.

The generally accepted indications for CT scanning are

  1. Significant displacement or dislocation, particularly if open reduction is contemplated.
  2. Suspected central dislocations of the condyle through the glenoid fossa, where it will also demonstrate the presence of any intra- or extracerebral haematoma
  3. Limited range of motion with a suspicion of mechanical obstruction caused by the position of the condylar segment
  4. Alteration of the surrounding osseous anatomy by other processes, such as previous internal derangement or TMJ surgery, to the point that a pre-treatment baseline is necessary
  5. Inability to position the multiple trauma patient for conventional radiographs.

The disadvantages of CT scans are the high cost, limited availability and radiation exposure.

Magnetic Resonance Imaging (MRI)

The MRI yields excellent soft tissue detail but lesser bony resolution compared to the CT scan. It may be used as an adjunctive study if significant soft tissue injury of the joint is suspected. It has the additional advantage of no ionising radiation exposure and the ability to obtain images in any desired plane of view by reconstructing the image data.

Harms et al (1985) used surface coil MR imaging in the diagnosis of internal derangement of TMJ. Modern techniques include MR fast scanning with T1 and T2 weighted imaging (Schellhas and Wilkes-1989) and dual-surface coil MR imaging of bilateral joints (Shellock and Pressman-1989). Schellas (1989) also used the MR to image the muscles of mastication. Accumulations of intra-articular fluid can be picked up by their signal intensity on GRASS (gradient-recalled acquisition in steady state) scans.

Arthrography

Arthography, by introducing a contrast medium into the upper and lower joint spaces, provide the best feasible method of visualising the position of the meniscus in internal derangement  (Wilke 1978). It is not a suitable method for use in acutely injured patient as it involves considerable subject co-operation during the examination. It can be combined with MRI as ‘two-compartment arthrography and MR’ (Schellhas et al 1988). Both methods can be used with a cinematic or videotape imaging to provide a dynamic scan in movement.


Management

The proper management of the fractured mandibular condyle is one of the most controversial topics in maxillofacial trauma. This controversy is reflected in a wide variety of opinions and proposed treatment modalities offered in the literature.

Goals of therapy

The objective of the surgeon treating condylar fractures is primarily directed towards functional rehabilitation. The generally accepted goals to be achieved in treatment are the following:

  1. Stable occlusion
  2. Restoration of inter-incisal opening
  • Full range of mandibular excursive movements
  1. Minimise deviation
  2. Relief from pain
  3. Avoid internal derangement of the TMJ
  • Avoid growth disturbance.

Conservative and functional management

This is a term used to cover all methods of treatment other than surgical intervention. Its objective is either to allow bony union to occur where there is no significant displacement of the condyle or in the case of fracture dislocation, to produce an acceptable functional pseudoarthrosis by re-education of the neuromuscular pathways. It appears that bony union occurs regardless of treatment if there is contact between proximal and distal fragments. These techniques are applicable therefore in all cases of unilateral or bilateral fracture other than in certain gross displacements in superior or lateral directions or certain other circumstances which will be detailed later.

The aims of conservative and functional treatment are to encourage active movement of the jaw as early as possible provided that the patient can bring his or her teeth into normal occlusion. Excessive pain or persistent malocclusion will require periods of intermaxillary fixation. Such a period of fixation should not exceed 10 days if there is a risk of ankylosis in circumstances, which has previously been outlined. In the case of children one must be aware of the remarkable remodelling capacity of the condyle which may persist in many subjects into teenage.

Dahlstrom et al in 1989 followed up 36 patients, 15 years after conservative treatment of condylar fractures. In 14 children there was o major growth disturbance observed and in most cases there were no signs of the earlier fracture and function of the masticatory system was good. In eight teenagers the anatomical and functional restitution of the TMJ was not as good as in the children, but hardly gave rise to objective symptoms. In 14 adults signs of dysfunction were frequently observed but not considered serious by the patients. The study involved careful analysis of the preceding fractures clinical examination including detailed measurement of mandibular mobility, estimation of biting force and radiographic analysis of the post treatment appearance of the articular fossa and the condylar head. Of the 14 adult patients assessed nine reported persisting discomfort although this was never rated as serious. Subjectively altered appearance was reported by three subjects and TMJ sounds were common in adult group. There was a significant reduction in the level of biting force.

Konstantinovic and Dimtrifevic (1992) compared 26 surgically and 54 conservatively treated unilateral condylar process fractures by standardised clinical examination and evaluation of computer stimulated graphic presentations of postero-anterior radiographs of the mandible. Surgical approach was through a submandibular incision with wire osteosynthesis. Using clinical parameter (maximal mouth opening, deviation, protrusion) no statistical differences between surgically and conservatively treated fractures were found. However the radiographic examinations showed a statistically better position of the surgically reduced condylar process fractures. At a minimum of 1 year after treatment the maximum mouth opening in both the groups has a mean of 3.9cm. A mean index calculated for deviation was 7.3% in both groups. In jaw protrusion also there was no significant difference. In conservatively treated group however there were no complications during the healing period, but in the surgically treated patients, four (15.4%) had infection of the wound and or transitory paresis of the marginal branches of the facial nerve.

Closed reduction

Placement of archbars or splints, immobilising the jaws for 2 to 4 weeks has been the mainstay of therapy for many decades.  Some authors have suggested that intermaxillary fixation (IMF) be used on all fractures as the initial insult leads to inflammation.

Lentrodt (1982) among other European authors believe that in displaced fractures of the neck of the condyle, the joint must be relieved of stress by opening the occlusion by 2 to 3 mm with an acrylic block in the distal molar region in the side of the fracture. They call this therapy ‘extension by means of a fulcrum’. The height of the fulcrum depends on the radiographically determined degree of ramus shortening. After 8 days, the fixation is removed and the patient is followed by functional movements with elastics applied in the anterior region.

According to the clinical data reported by MacGregor and Fordyce (1957), bony union appears to occur after condylar fractures regardless of whether intermaxillary fixation is employed or not. Similar observations have been made in experimental fractures in the rhesus monkey (Walkers-1960, Boyne-1967).

Open reduction

In surgical (open) reduction, the objective is to perform a repositioning of the fractured condyle as near to its anatomical location as possible. This is achieved by exposing the condylar fragment, reducing it to a normal relationship with the mandibular fragment and then fixing it in that position.

As the results of conservative treatment are good overall with a dysfunction rate of 15%, it is essential to decide which cases merit a surgical approach. Moreover surgical access in cases of fracture dislocations tends to be difficult with a real risk to branches of 7th cranial nerve and the maxillary artery.

Indications

Zide and Kent (1983) divided indications for open reduction of a condylar fracture into absolute and relative. The absolute indications are

  1. Displacement of the condyle into the middle cranial fossa
  2. Inability to achieve occlusion with a closed reduction
  3. Lateral fracture-dislocation of the condyle and
  4. Invasion of the joint space with a foreign body.

Relative indications for open reduction include

  1. Bilateral condylar fractures where establishing vertical facial height is important.
  2. Associated injuries that dictate early or immediate function
  3. Associated medical conditions that indicate an open reduction is preferable to maxillo-mandibular fixation and
  4. Conditions in which treatment has been delayed and early healing in a malaligned position has commenced.

Surgical approaches

The selection of surgical approach for open reduction depends on a variety of factors, which include the level at which the fracture has occurred, the degree of displacement or dislocation and the planned method of fixation.  Other factors are the quest for optimal access for visualisation and instrumentation, aesthetic factors like scarring, minimising injury to vital structures like nerves, blood vessels and ducts of salivary glands, surgeon’s convenience and patient preference.

The advantages of all extra-oral approaches are that a fracture is visualised and approached more directly than from an intra-oral approach. Each of the different approaches is designed to prevent or minimise injury to the branches of the facial nerve. The major disadvantages of all extra-oral approaches are visible scars and possible injury to the branches of the facial nerve.

It is claimed that the intraoral technique obviates the known complications of external open reduction such as the possibility of facial nerve injury, external scar, ischaemic compromise to the proximal segment and undoubted technical facilities. The main disadvantage of this approach is that exposure of the condylar segment is limited. Orientation and stabilisation of the fragment can at times be difficult. This is especially true if the fragment is medially displaced.

The options for access to fracture site of the condyles include

  1. Intra-oral approach
  2. Pre-auricular approach
  3. Retromandibular approach
  4. Submandibular approach

1.     Intra-oral approach

The intra-oral approach is indicated for minimally displaced low subcondylar or ramus fractures where the patient needs to have function. The technique of intra-oral approach to the fractured condyle was first described by Steinhauser in 1964 and was amplified by Niederdellmann (1986) and Jeter et al (1988). Lachner et al (1991) published the first results of a series of patients who had been surgically treated by intraoral open reduction of subcondylar fractures with semirigid fixation by use of miniplates.

This approach is very similar to that used in an intra-oral ramus osteotomy procedure. The mouth is propped open with a biteblock. Local anaesthetic with vasoconstrictor is injected into the medial and lateral regions of the mandibular ramus. An incision is made approximately halfway up the ascending ramus through the periosteum overlying the external oblique ridge. The lateral aspect of the ramus is exposed so that the entire surface of the ramus from the sigmoid notch to the angle region is exposed. When a condylar segment is medially displaced, the segment can be uprighted by sliding a periosteal elevator on the medial aspect of the ramus above the entrance of the inferior alveolar nerve. When the posterior elevator contacts the fragment, it can be used to push the fragment posterior and lateral. Fixation is accomplished through a combination of percutaneous incisions and lateral manipulation of plates and screws.

2.     Pre-auricular approach

The extra-oral pre-auricular approach with rigid fixation has been described by Koberg and Momma (1978), Petzel (1982) and Choung and Piper (1988). Al Kayat and Bramley in 1979 described a question mark shaped incision and elevation of a flap that includes in it both the main branches of the superficial temporal artery.

The preauricular incision gives a limited view of a fractured joint. The skin incision maybe made in a pre-auricular crease. The plane of dissection is immediately adjacent to the external auditory canal. As such the facial nerve injury is prevented by approaching from behind the major branches of facial nerve. Once the dissection reaches bony structures, the nerve branches are protected in the overlying soft tissue.

The incision begins at the anterior-superior base of the helix and is continued along the curvature inferiorly toward the crus helicis in the natural skin fold. Retracting the skin with digital pressure, the incision is carried over the crest of the tragus, following the outline. Dissection is carried on anteriorly along the cartilage just anterior to the perichondral plane to the level of the capsule. Superiorly, dissection is carried down to the temporalis fascia.  These two regions are then joined by blunt and sharp dissection through the confluence of fascia over the zygomatic arch. At this point, the joint capsule will be visible. Opening into the superior joint space is made by sharply incising over the superior glenoid tubercle and extending inferior through the capsule, and the condylar head is exposed. Placement of a towel clamp or a similar instrument to distract the distal segment is often necessary. A 0.62 threaded K-wire can be used to engage and control the proximal segment.

3.     Retromandibular approach

The retromandibular approach gives the best access to the fractures of the condylar neck with a single incision. It was first described by Hinds (1958, 1967, 1972). It provides excellent exposure of the ramus and the subcondylar region. Ellis and Zide (1995) believe that this approach allows access to the ramus by spreading between the buccal and mandibular branches of the facial nerve. This accounts for the low incidence of facial paralysis with this approach.

The incision is about 2.5 cm long and is made posterior and parallel to the posterior border of the ascending ramus from a point just below the lobe of the ear inferior to a point just above the angle of the mandible. The incision is vertical and is about 2 cm behind the posterior border of the mandible. The initial skin incision extends through the skin and subcutaneous tissues. Once down to the platysma, the dissection is bluntly directed forward toward the posterior border of the mandible. Zide and Ellis used sharp dissection of platysma while Van Sickels and Parks (1999) recommends blunt dissection. The dissection is below and behind the superficial lobe of the parotid. When the posterior border of mandible is reached, the tissues are bluntly spread, exposing the ramus. The pterygomasseteric sling is either sharply or bluntly dissected in a subperiosteal plane superiorly toward the fracture.

Rhytidectomy incision

The rhytidectomy incision has the advantages of a retromandibular incision and a good cosmesis. It was originally described as a ‘face-lift’ approach by Zide and Kent in 1983 to access the fractured condyle. It was described as a preauricular incision under the lobe of the ear that extended postauricularly on the posterior surface of the auricle.

In 1995, Ellis and Zide described this approach as a variant of the retromandibular approach with better cosmesis. The major disadvantage is the added time required to close the broad incision. The incision begins approximately 1.4 to 2 cm above the zygomatic arch. It can be just anterior to the pinna and continues under the lobe of the ear and approximately 3-mm onto the posterior surface of the auricle. It continues posteriorly toward the hairline for a few centimetres. The initial incision is carried through skin and subcutaneous tissue. A skin flap is elevated through this incision, using sharp and blunt dissection undermining to create a subcutaneous pocket that extends below the angle of the mandible and a few cms anterior to the posterior border of the mandible. From here, the dissection continues as described for the retromandibular approach.

4.     Submandibular approach

Access to the mandibular ramus, angle and posterior body is readily achieved with the submandibular approach, initially described by Risdon in 1933. It is seldom used alone for isolated condylar fractures. Visualisation of the superior aspects of the ramus is difficult with this approach. It is most useful for low subcondylar fractures and ramus fractures. Although the scar is hidden in a skin crease, cosmesis is not very good. This approach may be combined with a pre-auricular incision for better access to the entire ramus. Transient weakness of the 7th nerve is frequently seen with this approach, probably as a result of retraction.

The incision is 4 to 5 cm long in the skin crease line. The initial dissection is carried sharply through skin and subcutaneous tissue down to platysma. The subcutaneous tissues are widely undermined. Dissection is continued in layers, going through platysma and the deep cervical fascia. The pterygomasseteric sling is divided at the inferior border of the mandible. Subperiosteal dissection of the ramus is done to expose the fracture. Distraction of the distal segment is necessary to allow for space to align the proximal segment.

Methods of immobilisation of the condyle

Once the proximal segment is visualised and the fracture reduced, the fragments can be immobilised in a number of ways.

Simple Soft Tissue Repair without Fixation:

This was described by Silverman in 1925 and there is a report by Raveh et al (1989).       It is combined with a period of intermaxillary fixation of approximately 10 days in the latter report. There must be a significant risk of re-displacement due to the action of the lateral pterygoid muscle although the results of the latter authors would appear to be satisfactory with deviation of more than 4mm seen in only one case out of 29 postoperatively.

Transosseous wiring

Transosseous wiring is occasionally used in low subcondylar fractures, particularly those extending through the sigmoid notch. This is done through a submandibular incision. First the major fragment is wired so that this may be used for a downward traction to improve access to the condylar fragment. For passing wire through the smaller condylar fragment, a pull through wire may be used.

For higher level fractures preauricular incision is used. Thoma (1945) advocated a specific sequence for this method. The fragments are drilled obliquely from the external surface to the fracture surface. If there is lateral overlap of the condylar fragment, this is drilled first. An instrument such as a small bone elevator is used to reverse the overlap so that the lower segment becomes accessible to drilling. A pull-through wire is again needed for the second insertion. In cases of medial overlap, this sequence is reversed.

In fracture dislocation, transosseus wiring alone may be insufficient to resist the displacing action of the lateral pterygoid muscle. One of the following additional methods may be employed unless the method of detaching lateral pterygoid insertion described by Hendrick et al has been used. An alternative lassooing type technique has been described by Messer (1972) which is claimed to give more stability.

Bone pins

Archer (1975) described the insertion of pins into the condylar head and neck which were connected with an external bar and universal joints. Thoma (1945) had previously described a similar technique but placed the pins in the condylar neck and zygomatic bone. This would need to be combined with period of intermaxillary fixation.

Glenoid fossa-condyle suture

Wassmund (1935) described drilling a small hole through the lateral edge of the glenoid fossa and the related edge of the condylar articulating surface. A chromic catgut suture was looped through and tied. It may however resorb and loosen prematurely with unpredictable results as reported by Herfert (1961).

Kirschner Wire

A Kirschner wire may be drilled vertically through the main mandibular fragment from the angle, avoiding the inferior alveolar bundle, so that it enters the fracture, interface and can be further inserted into the condyle, which has previously been reduced (Lund-1972, Vero-1968). This technique has been modified by Brown and Obeid (1984) whereby Kirschner wire is inserted into the proximal condylar fragment and after this a groove is cut for its base in the main distal mandibular fragment. Two interosseus wires are then used to secure the basal part of the pin.

Intramedullary Screws

Petzel (1982) described use of an intramedullary screw transfixing the distal and proximal fragments. The screw was inserted through a submandibular approach. Kitayama (1989) described the use of similar type of screw via an intraoral approach. Specialised instruments like tapping drills, a variety of lengths of screws and specialised forceps are required for placing the screws.

Bone Plating

The use of small compact bone plates has tended to revolutionise practice in relation to stabilising the fracture proximal condylar fragment and should be regarded as the method of choice in view of its rigidity and relative ease of application. Robinson and Yoon (1960) mentioned two holed plates while Koberg and Momma (1978) advocate a four-hole plate, which has tended to become standard. An added advantage is that bone plates can be placed on a relatively small proximal fragment first, allowing for the creation of a handle to more effectively manipulate the fragment into an appropriate reduction. Currently available bone plating systems are equipped with instrumentation for percutaneous placement of screws, a provision which may be of use in cases where the incision do not allow for adequate access.

Three useful plating techniques are described.

  1. Extra-oral approach through the preauricular route
  2. Intraoral approach
  3. Osteotomy – extracorporeal reduction technique through a submandibular incision.

Extra-oral Approach through Preauricular Route and Plating:

The following has been described by Koberg and Momma (1978). Under general anaesthesia a preauricular Al-Kayat and Bramley incision is made. The incision is deepened carefully in layers with plane superficial to perichondrium of external auditory meatus. By careful blunt dissection the fractured surface of proximal fragment is located and identified.

Next step is gentle reduction into anatomical position of the proximal fragment. A helpful technique is by insertion of a bone pin into the neck and manipulating the proximal fragment into its correct position. Extensive stripping of soft tissue attachment should be avoided in order to reduce risk of ischaemic necrosis.

The jaws should be placed in intermaxillary fixation so that the proximal fragment can be manipulated into a correct relationship with the distal segment. Once this is attained a miniature four-hole plate of Wurzburg type is used to maintain the relationship. The incision closed in layer A miniature suction drain helps in reducing ecchymoses. It may be helpful in placing the patient in training elastics for 2-10 days.

Choung and Piper (1988) described reduction of the condyle in the manner indicated above together with concomitant repair of the discal injury. Once the condyle has been plated, the operating microscope is used to facilitate any necessary manipulations on the meniscus.

Intraoral Approach and Plating

The following account is based on the technique described by Lachner et al (1991). Early case selection confined itself to displaced low subcondylar neck fractures (extra capsular). The stages in the procedure were as follows.

Under general anaesthesia the subcondylar fractures were first managed by the following technique and subsequently other mandibular fractures were treated. Incision was put along the anterior border of ascending ramus and the masseter muscle was reflected laterally to the posterior border at a subperiosteal level. The sigmoid notch was identified so that Bauer type retractor could be positioned on it. The proximal segment was then carefully identified. If this proximal segment was displaced medially the mandible was distracted inferiorly with Mason type gag to position the proximal segment laterally.

A four-hole miniplate of Wurzburg type was then attached to the proximal segment with one or two screws. The periosteum of the proximal segment was elevated only to the degree necessary for plate placement so as to preserve as good as blood supply as possible. A percutaneous trocar was placed through a horizontal stab incision in the pre-auricular region (this should be done bluntly after initial skin incision so as to avoid damage to facial nerve branches) so that the correct angulation could be obtained for making the drill holes. Intermaxillary fixation was instituted. The plate was then attached to the distal segment with two further screws.

The incision was closed. Patients were training elastics between their fixation bars for 2-10 days.

Submandibular Approach for Osteotomy – Extracorporeal Reduction Technique:

Mikkonen et al (1989) described access to a fracture dislocation of the condylar head through a submandibular approach which was combined with a vertical subsigmoid osteotomy of the ramus to locate the proximal fragment. The minor osteotomised segment plus the condylar head were then reduced extracorporeally and firmly joined together before reimplantation in their correct anatomical position. This obviously required sectioning of the attachment of the lateral pterygoid muscle to the condylar head.

This technique which was originally described in conjunction with inter-osseous wiring has been modified as follows for use with bone plates by Schnetler and Juniper (1992). In their approach, a submandibular incision is made and the ascending ramus divided between the sigmoid notch and the angle of the mandible using a technique similar to that used in a vertical subsigmoid osteotomy. Bare miniplates are fitted and then removed prior to the completion of osteotomy cuts. After the fragment is removed the dislocated head of the condyle is readily visible and can be retrieved through the same incision. The fracture site at the condylar head can be reconstructed with ease away from the patient and semirigid fixation applied using a miniplate. The reconstructed osteotomised ramus and condylar head can now be reinserted through the wound and plated to the predetermined position. Downward traction on the mandible is usually required at this point and has been achieved with a circum-mandibular wire brought out through the submandibular incision. Post operatively early mobilisation of jaw is encouraged. The authors report three successful cases. They mentioned the risk of avascular necrosis but state that reports to date do not suggest that this has been a problem.


Specific Treatment of Condylar Fractures:

The following factors should be considered.

  1. The age of the patient whether under 10 years of age, 10-17 years of age, adults.
  2. Whether the fracture is intracapsular or extracapsular (low condylar neck or high condylar neck)
  3. Site, whether unilateral or bilateral
  4. Whether the occlusion is undisturbed or whether there is malocclusion.

Children under 10 years of age:

This group has been shown to be more likely to develop growth disturbance or limitation of movement than other groups. If malocclusion is present entirely as a result of condylar injury it should be disregarded because spontaneous correction will take place as the dentition develops. Displaced condylar neck fractures will undergo functional restitution in most cases. Unilateral and bilateral fractures are treated the same. Treatment should be entirely functional where possible. Indirect immobilisation by intermaxillary fixation is indicated for control of pain and should be released after 7-10 days. Where an intracapsular fracture has been diagnosed careful follow up and monitoring of growth is required and treatment with myofunctional appliances instituted if subsequent mandibular development is reduced.

Adolescents:   10-17 years of age

The same principles apply to this group with some modification. If malocclusion is present, the capacity for spontaneous correction is less than in younger group. Malocclusion is therefore an indication for intermaxillary fixation for 2-3 weeks. The dentition at this stage is suitable for application of simple eyelet wires.

Adults:

Unilateral Intracapsular Fractures:

The occlusion is usually undisturbed and the fracture should be treated conservatively without immobilisation of the mandible. Occasionally slight malocclusion is noted, particularly when there is associated effusion in the joint in which case simple intermaxillary fixation with eyelet wires should be applied for 2-3 weeks.

Unilateral condylar neck fractures:

If the fracture is undisplaced the occlusion will generally be undisturbed and no active treatment is necessary. A fracture dislocation will often induce significant malocclusion due to shortening of ramus height and premature contact of molar teeth on that side. A low condylar neck fracture is probably best treated by open reduction in these circumstances.

In the case of a high condylar neck fracture with extensive displacement and malocclusion, intermaxillary fixation is applied and maintained until stable bony union has occurred i.e. 3-4 weeks. In spite of maintaining occlusion by intermaxillary fixation relapse may take place when the fixation is removed. As that is usually slight it can be corrected by a combination of occlusal grinding and spontaneous adaptation.

Bilateral Intracapsular Fractures:

The occlusion is usually slightly damaged in these cases. The degree of displacement of the two condyles may not be the same and it is best to immobilise the mandible for the 3-4 weeks required for stable union. It used to be thought that this would predispose to chronic limitation of movement but post-reduction physiotherapy in the form of simple jaw exercises if effective in preventing this.

Bilateral condylar neck fractures:

These fractures present the major problem in treatment. There is usually considerable displacement of one side and/or the other. Even if displacement is not evident when first seen, the fractures are inherently unstable and functional treatment is contraindicated. Although the application of intermaximally fixation will establish occlusion, it will not reliably reduce the fracture on both sides. Operative reduction of atleast one of the fractures to restore ramus height is desirable. In the case of bilateral high condylar neck fractures, where operative reduction is likely to be difficult, intermaxillary fixation should be applied for up to 6 weeks. If strong arch bars or even cap splints are applied this will allow the use of intermittent intermaxillary elastics at night for several weeks after fixation is removed. This technique may encourage better functional remodelling.

Although ankylosis of the temporomandibular joint itself does not occur with condylar neck fractures, exuberant callus formation round grossly displaced fragments may cause extra articular interference with joint excursion. When a bilateral fracture of this nature is associated with a major mid facial fracture, operative reduction on both sides is desirable. It should be appreciated that this represents a considerable amount of operating time even in skilled hands. The situation may be temporarily saved by the use of extra-oral fixation utilising a box-frame or halo.


Post-operative care and follow-up

Whether the patient has had a closed or open reduction, post-operative physiotherapy is an integral part of treatment. There are a variety of protocols that can be used. In essence, the patient should be given progressive exercises to restore the rage of motion in all dimensions. These should be done while assuring a satisfactory occlusion.

Training elastics are frequently employed after surgery to maintain the occlusion. This usually means having two elastics present: one on the side of the fractures with a slight Class II (anterior) vector of pull and the other on the opposite side with a straight up and down vector of pull. Initially the patients should wear the elastics continuously. Within one week, they can be changed, allowing function during meals and oral hygiene. Within 2 weeks, elastics can be used at night. At 3 weeks the archbars and elastics can be removed. Diet should be restricted to soft foods for 8 weeks.


Complications

In considering any treatment, the potential for complications exists. These complications may be divided into those occurring early in the course of injury or treatment and those that occur later.

Early complications

Complications that occur concurrent with or early after treatment of condylar fractures include the following

Fracture of the tympanic plate and middle ear injury

A force transmitted through the mandible from the anterior to the posterior through the condyles will be transferred to the tympanic plate, and may cause its fracture. Owing to the close proximity of the plate and the external auditory canal, the primary symptom of this injury is bleeding from the ear. It may also cause a conductive hearing loss because of the close proximity to the middle ear. Patients with history of condylar fractures should undergo a careful otoscopic examination.

Fracture of the glenoid fossa

Fracture of the base of the skull might occur in the region of the relatively thin glenoid fossa and occasionally extends to the petrous portion of the temporal bone. It is thought that the unique scroll-like shape of the condylar head, with its large lateral pole, and the increased thickness of the lateral aspect of the fossa provide protection against penetration of the condylar head into the cranium. In certain cases, however, the condyle is more rounded in form, and this feature is thought to allow increased concentration of forces in the thin central portion of the glenoid fossa. This causes the fossa to fracture with possible penetration of the condyle into the middle cranial fossa.

Computed tomography scan is the best method of visualisation of condylar displacement into the middle cranial fossa. It can also detect concurrent intracranial haematomas.

Neurosurgical consultation is warranted to exclude cerebral damage, intracranial haemorrhage and cerebrospinal fluid leak. Reduction of the fracture and some period of immobilisation should be done. If required, a bone grafting of the glenoid fossa may be done.

Damage to cranial nerves

Basilar skull fracture might result in cerebral contusion. The spread of fracture through the petrous temporal bone can cause injury to the seventh and/or eighth cranial nerves, producing a neurosensory hearing deficit and facial paralysis. Damage to the nerves can also occur as a result of being stretched during the injury, lacerated or severed by the jagged edge of fractured bone ends, or iatrogenically damaged during surgical intervention. The facial nerve is again susceptible during condylar injury or during surgical treatment. Overriding of the condylar segment medially may cause injury to the inferior alveolar nerve as it enters the mandibular foramen at the lingula.

Vascular injury

Damage to the vascular structures can occur in a similar way. The internal maxillary artery is especially prone to injury as it travels just medial to the condyle. This might result in haematoma formation or development of a false aneurysm.

Late complications

The late complications of condylar injury commonly include the following.

Malocclusion

Malocclusion following condylar trauma may result from alterations in the condylar growth centre and/or malunion of the fracture segments. A properly timed and supervised program of training elastics and physiotherapy can avert significant malocclusion in a majority of cases. If the problem persists, the use of judicious occlusal equilibration, orthodontics or orthognathic surgery may be required. Before reconstruction of the occlusion to this new articulation, it is necessary to allow a period of 6-12 months for complete healing and any remodelling of the articular apparatus to occur. Most patients are amenable to conservative therapy and are able to compensate for a small degree of occlusal disharmony. In the edentulous patients, differences in the inter-occlusal relationship can be compensated for during the fabrication of new prostheses.

Growth alteration

Growth alterations as the result of condylar injury may occur as a result of two mechanisms: over/understimulation of the normal growth may result from direct injury to the condyle, or a restriction of normal growth may occur secondary to fibrosis or scarring of the surrounding tissues. Factors influencing the effect of condylar injury on growth include the age of the patient, the severity of the injury and the period of immobilisation.

Contrary to previous beliefs, it is now accepted that the growth deficit produced is not directly proportional to the age of the patient at the time of injury. This may be due to the fact that actively growing young individuals have the ability to regenerate the traumatised tissues to a good extent. The concept that condylar cartilage acts as a growth centre has been replaced by the ‘functional matrix’ theory, according to which the cartilage acts as a remodelling centre, which would influence future growth patterns.

If normal growth is disrupted, the affected ramus height is reduced while the unaffected side is allowed to grow normally. These inequality results significant facial asymmetry characterised by a shortened lower facial height, bowing of the inferior border and marked antegonial notching on the affected side, and an elongated inferior mandibular border and flattened facial contour on the contralateral side. As the patient attempts to establish a workable occlusion, many dental compensations occur, such as posterior crossbite on the affected side, a canting of the occlusal plane, tilting of dento-alveolar segments etc.

Temporomandibular joint dysfunction (Internal derangement)

As discussed by Goldman in 1991, a wide variety of injuries can result in the development of internal derangement of TMJ. There is a greater incidence of TMJ pain, deviation on opening and joint noise in patients with previous condylar fractures. The resultant internal derangement typically occurs in adults and is of two broad types. The first type occurs on the side of the fracture and is due to soft tissue injury within the joint. Open reduction with direct repair of the injured soft tissues has been advocated by some as a possible means of preventing this problem. The second type occurs contralateral to the condylar injury.  This derangement was described by Gerry (1965) as ‘condylar post-fracture syndrome’. Patients who develop a unilateral hinge type of joint after fracture can rapidly develop overfunction of the contralateral joint with hypermobility and, ultimately, anterior dislocation of the meniscus.

Ankylosis

Ankylosis of the TMJ is the most serious complication of condylar fracture. This is the development of significant or complete limitation of movement of temporomandibular joint by bone or fibrous tissue. Trauma is the leading cause of TMJ ankylosis (31% to 98% in various studies).

Laskin (1978) has carefully evaluated the factors that could contribute to the development of post-traumatic TMJ ankylosis.

Age of patient:

There is greater predisposition in younger than older patients and majority of reported cases have sustained such injuries before the age of 10 years (Topazian, 1964).

Site and type of fracture:

The intracapsular fracture is having high risk of ankylosis. This is especially so in children whereas pointed by Rowe (1969, 1982), the immature thinly covered and highly vascular condyle may tend to burst open, with resultant haemarthrosis containing multiple comminuted fragments of bone with a high osteogenic potential.

Laskin considered that the most important feature in fracture encouraging ankylosis is close contact between glenoid fossa and condylar stump and that this is more likely to occur with intracapsular fracture than with extracapsular fractures. Despite this only a relatively small number of cases of ankylosis occur in comparison with incidence of intracapsular fractures.

Duration of immobilisation:

Many authors point out the dangers of prolonged immobilisation but experimental work in primates (Markey-1980) has failed to produce ankylosis by this means after artificially produced condylar fractures. It is likely therefore that immobilisation is a contributory factor rather than a primary cause.

Damage to Meniscus:

Laskin has suggested that the position and the state of the meniscus may be the key factor in determining whether posttraumatic ankylosis will develop. Even when there is close relationship of the condylar stump to the glenoid fossa, the meniscus can act as a barrier to bony union, but if this is damaged or misplaced then ankylosis may occur as is demonstrated by experimental evidence from animal studies (Wheat et al, 1977).

In summary, the situations in which the risk of ankylosis is greatest comprise

  1. Close proximity of the fractured condylar neck to the glenoid fossa which is seen in:

Intracapsular fractures

Fracture dislocation with gross telescoping

Compound fractures particularly when coronoid and zygomatic areas are also involved.

  1. Patients under 10 years of age.

Clinically, the patients with TMJ ankylosis present with a greatly reduced inter-incisal distance and secondary facial deformities. The latter include significant mandibular retrusion, facial asymmetry in unilateral cases and occasionally, anterior open bite in bilateral cases.

Conclusion

Fractures of the mandibular condyle constitute a significant portion of mandibular fractures. A number of clinical signs and symptoms are characteristic of injury to the condylar apparatus. The use of plain radiographs in multiple view, or CT scans discloses most condylar fractures and displacements, if any. A number of classification systems are available to help in treatment planning and record keeping.

Non-surgical treatment is adequate for a majority of condylar fractures. A period of immobilisation followed by active functional therapy is indicated for most cases. Surgical management has specific indications, and can be accomplished through a wide variety of techniques. In general, complications are not common following condylar trauma. Important among the possible complications are ankylosis, growth disturbances and internal derangement.

References

  1. Principles of Oral & Maxillofacial Surgery. Peterson, Marciani and Indresano. Vol. I
  2. Oral and Maxillofacial Surgery. R. J. Fonseca Vol. III
  3. Killey’s fractures of the mandible
  4. Rowe and Williams Maxillofacial Injuries. Vol. II
  5. Oral & Maxillofacial Traumatology. Kruger and Schilli Vol. II
  6. Oral and Maxillofacial Trauma. Edited by R. J. Fonseca and R. V. Walker. Vol. I. 2nd
  7. Conservative treatment of unilateral condylar fractures in children: a long-term clinical and radiologic follow-up of 55 patients. Stobl et al. International Journal of Oral and Maxillofacial Surgery Vol. 28. 1999. Pages 95-98

 

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Author:

I am a practicing maxillofacial surgeon working in India.

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