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SELECTED TOPICS CHIP FRACTURES OF THE MANDIBULAR CONDYLE Elieser Avrahami, MD, and lsaak Horowitz, MD Abstract: Four patients suffered from trauma of the temporomandibular (TM) joints. They were exam- ined by routine x-ray procedures. The x-ray films failed to demonstrate a chip fracture of the head of the mandibular condyle. A coronal computed to- mographic (CT) view established the fracture shortly after the trauma in three patients. These pa- tients improved clinically after physiotherapy. The fourth patient was retrospectively diagnosed as having a chip fracture of the mandibular head. She underwent CT scan 10 months posttrauma, and an- kylosis of the TM joint was established. The mecha- nism and the clinical symptoms of this injury, which have not been previously described, are reported in this article. HEAD & NECK SURGERY 6:978-981 1984 Chip fractures of the medial part of the head of the mandibular condyle are rarely documented. Routine x-ray procedures, including tomography, can miss this fracture. The normal position of the undislocated mandibular condyle makes diag- nosis extremely difficult when using routine x- ray examinations. The coronal computed tomog- raphy (CT) view of the temporomandibular (TM) From the Deparlment of Diagnostic Radiology (Dr. Avrahami) and the Oral Surgery Unit (Dr. Horowilz), Tel-Aviv Medical Center, lchilov Hos- pital and Tel-Aviv University Sackler School of Medicine, Tel~Aviv, Is- rael. Address reprint requests to Dr. Avrahami at the Department of Diag- nostic Radiology, Tel-Aviv Medical Center, lchilov Hospital. 64 239 Tel Aviv, Israel. Accepted for publication April 28, 1983 "1984 John Wiley 8 Sons, Inc. 01 48-6403/0605/0978 $04.00/0 joint, however, establishes the diagnosis, which is of high medical and legal importance. Computed tomographic examination of the TM joints that includes two or three coronal cuts can be expeditely performed. It usually offers more accurate diagnostic information than the noncomputerized x-ray procedures. MATERIALS AND METHODS Two patients who had a single chip fracture of the mandibular condyle, one patient who had a chip fracture combined with a contralateral, high con- dylar fracture-dislocation, and a fourth patient who had bone ankylosis of the TM joint following a supposed chip fracture were subject to x-ray and CT studies of the TM joints. The clinical observa- tions of the patients affected by chip fractures and TM joint fractures were similar. The joint was tender, but there was no local swelling. The occlu- sion of the teeth had not been disturbed. The patients experienced moderate pain in the area of the affected joint, which was mainly ag- gravated by eating. The patient with ankylosis (case 4) had had the same clinical symptoms pre- viously. The x-ray studies included bilateral views of the TM joint, with the x-ray beam directed 25" caudad to each side; a reversed hemiaxial (Town) view, with a beam 30" caudad; a panoramic view; and anteroposterior (AP) and lateral tomographic views.' All these views failed to demonstrate the chip fractures. The coronal CT view of the TM joint, which established the diagnosis, had been performed with a beam parallel to the cantho- 978 Chip Fractures of the Mandibular Condyle HEAD 8. NECK SURGERY MayiJune 1984

Chip fractures of the mandibular condyle

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SELECTED TOPICS

CHIP FRACTURES OF THE MANDIBULAR CONDYLE

Elieser Avrahami, MD, and lsaak Horowitz, MD

Abstract: Four patients suffered from trauma of the temporomandibular (TM) joints. They were exam- ined by routine x-ray procedures. The x-ray films failed to demonstrate a chip fracture of the head of the mandibular condyle. A coronal computed to- mographic (CT) view established the fracture shortly after the trauma in three patients. These pa- tients improved clinically after physiotherapy. The fourth patient was retrospectively diagnosed as having a chip fracture of the mandibular head. She underwent CT scan 10 months posttrauma, and an- kylosis of the TM joint was established. The mecha- nism and the clinical symptoms of this injury, which have not been previously described, are reported in this article.

HEAD & NECK SURGERY 6:978-981 1984

Chip fractures of the medial part of the head of the mandibular condyle are rarely documented. Routine x-ray procedures, including tomography, can miss this fracture. The normal position of the undislocated mandibular condyle makes diag- nosis extremely difficult when using routine x- ray examinations. The coronal computed tomog- raphy (CT) view of the temporomandibular (TM)

From the Deparlment of Diagnostic Radiology (Dr. Avrahami) and the Oral Surgery Unit (Dr. Horowilz), Tel-Aviv Medical Center, lchilov Hos- pital and Tel-Aviv University Sackler School of Medicine, Tel~Aviv, Is- rael.

Address reprint requests to Dr. Avrahami at the Department of Diag- nostic Radiology, Tel-Aviv Medical Center, lchilov Hospital. 64 239 Tel Aviv, Israel.

Accepted for publication April 28, 1983

"1984 John Wiley 8 Sons, Inc. 01 48-6403/0605/0978 $04.00/0

joint, however, establishes the diagnosis, which is of high medical and legal importance.

Computed tomographic examination of the TM joints that includes two or three coronal cuts can be expeditely performed. It usually offers more accurate diagnostic information than the noncomputerized x-ray procedures.

MATERIALS AND METHODS

Two patients who had a single chip fracture of the mandibular condyle, one patient who had a chip fracture combined with a contralateral, high con- dylar fracture-dislocation, and a fourth patient who had bone ankylosis of the TM joint following a supposed chip fracture were subject to x-ray and CT studies of the TM joints. The clinical observa- tions of the patients affected by chip fractures and TM joint fractures were similar. The joint was tender, but there was no local swelling. The occlu- sion of the teeth had not been disturbed.

The patients experienced moderate pain in the area of the affected joint, which was mainly ag- gravated by eating. The patient with ankylosis (case 4) had had the same clinical symptoms pre- viously.

The x-ray studies included bilateral views of the TM joint, with the x-ray beam directed 25" caudad to each side; a reversed hemiaxial (Town) view, with a beam 30" caudad; a panoramic view; and anteroposterior (AP) and lateral tomographic views.' All these views failed to demonstrate the chip fractures. The coronal CT view of the TM joint, which established the diagnosis, had been performed with a beam parallel to the cantho-

978 Chip Fractures of the Mandibular Condyle HEAD 8. NECK SURGERY MayiJune 1984

Page 2: Chip fractures of the mandibular condyle

FIGURE 1. Case 1. (A) A view of the right TM joint. The head of the mandible is into the glenoid fossa (normal position) and does not indicate any fracture of the head. Tomography was normal. (B) A coronal CT scan. Chip fracture of the medial surface of the right mandibular condyle. The fragment lies below the head (arrow).

meatal line. The width of the coronal slices was 10 mm.2-5

CASE REPORTS

Case 1. A 25-year-old woman fell from her bicycle and a 2-cm jaw laceration was observed on physi- cal examination. The patient complained of a moderate pain when she opened her mouth. The movements of the mandible were not limited and there was no dental malocclusion. Palpation re- vealed a tenderness of the right TM joint and was the reason for the decision to perform x-ray inves- tigations.

An AP view of the TM joint, an inverted Town view, a view directed to the right TM joint, and tomography were unremarkable (Fig. 1A). The coronal CT scan of the right TM joint demon- strated a small bone fragment just below the right condylar head, which was not dislocated (Fig. 1B).

Following this diagnosis, the patient under- went intensive physiotherapy. Six months later, she was able to freely open her mouth without any associated pain.

Case 2. A 23-year-old male boxer complained of pain of the right TM joint after a boxing match. The pain was most severe when he was eating. On physical examination, the area on the right TM joint was found to be tender. No disturbances of dental occlusion were present and the area was not swollen.

Routine x-ray procedures, including tomog- raphy, were considered normal. The coronal CT

scan demonstrated a bony fragment below the rest of the fractured right condylar head, which remained undislocated into the glenoid fossa (Fig. 2).

An intensive course of physiotherapy, which lasted 3 months, resulted in complete restoration of jaw movements.

Case 3. A 29-year-old man fell from a 6-m high building. He complained of a severe pain in both TM joints, which increased when he tried to open his mouth. The opening was limited to a few mil-

FIGURE 2. Case 2. A coronal CT scan. The chip fragment (arrow) is demonstrated below the undislocated right condy- lar head.

Chip Fractures of the Mandibular Condyle HEAD & NECK SURGERY MayiJune 1984 979

Page 3: Chip fractures of the mandibular condyle

FIGURE 3. Case 3. A coronal CT scan. Left high condylar fracture-dislocation associated with a chip fracture of the right condylar head (arrow). FIGURE 4. Case 4. A coronal CT view. There is ankylosis of

the left TM joint (arrow).

limeters. The area of the left TM joint was swol- len and tender. The right TM joint was tender but not swollen. The occlusion of the left molars had been slightly disturbed; the right molars were well occluded.

The view of the left TM joint showed an “empty glenoid fossa,” which indicated a high condylar fracture-dislocation. The fracture had been demonstrated by tomography of the left TM joint. The routine examinations on the right TM joint had been reported as normal.

The coronal CT scan of the TM joints demon- strated a high fracture-dislocation of the left mandibular condyle and a chip fracture of the me- dial part of the undislocated right mandibular condyle (Fig. 3).

After 5 months of intensive physiotherapy, the patient had partially improved and could open his mouth 4 cm.

Case 4. A 16-year-old diabetic woman was found unconscious following a hypoglycemic faint. On regaining consciousness, she complained of a pain in the area of the left TM joint, which increased when she opened her mouth. Except for a mild tenderness in the area of the joint, there were no significant findings on physical examination. The routine x-ray examinations, including tomog- raphy, were considered normal. No CT examina- tion had been added to the x-ray routine.

Two months later, the ability to open her mouth was gradually limited. Ten months after the onset of the pain, the maximal opening of the

mouth was assessed at 3 cm. The coronal CT scan demonstrated ankylosis of the left TM joint (Fig. 4).

DISCUSSION

Fractures of the mandibular condyle are usually caused by indirect violence. The zygoma protects the TM joint against direct forces. The mecha- nism is a blow to the symphysis of the mandible. This may occur from fainting (during a grand ma1 seizure in epileptic patients, for example) or as a consequence of a motor vehicle accident. The frac- tures of the mandibular condyle could be extra- or intracapsular. The extracapsular fractures, which may be termed low or subcondylar, run from the lowest point of the curvature of the man- dibular neck obliquely to the posterior aspect of the upper part of the ramus. The intracapsular fractures running through and above the anatom- ical neck, which do not involve the articular sur- face, are termed high condylar fractures. 1,5-8

Fractures involving the articular surface of the TM joint have been poorly investigated. They are not often visualized by routine clinical and x-ray examination. We believe that a complete destruction of the articular surface following trauma is rare. It would seem that the chip frac- ture of the mandibular condyle that involves the articular surface is not a rare condition. The force acting below the symphysis in a cranial direction is usually moderate. It is, however, strong enough to result in a temporary dislocation of the man-

980 Chip Fractures of the Mandibular Condyle HEAD & NECK SURGERY MayiJune 1984

Page 4: Chip fractures of the mandibular condyle

dibular head, which moves up. This force is not strong enough to result in tearing the capsule and the ligaments that return the mandibular head down into the glenoid fossa. During the cranial movement of the head, the chip fracture occurs. The chip fragment that belongs to the most me- dial part of the mandibular head remains, by this movement, in the glenoid fossa but below the mandibular head, which has already moved cra- nially. In the next movement, the head returns with a downward excursion to the glenoid fossa and, with it, moves the chip fragment down. In this final state, the chip fragment should be found below the mandibular head and outside the glenoid fossa (cases 1 and 2). We termed this kind of fracture simple. The simple chip fracture leaves sufficient function of the mandibular head intact. The patients do not have any limitation of the opening of the mouth and the teeth are well occluded. The clinical symptoms are minimal: tenderness in the affected area and a moderate pain aggravated by eating and opening the mouth.

If there is an accompanying mandibular frac- ture, e.g., contralateral high fracture-dislocation as in case 3, loss of stability results and occlusion

becomes impaired. We termed this condition com- plicated chip fracture.

The routine x-ray procedures, including to- mography of the TM joints, missed the chip frac- tures in cases 1, 2, and 3. Most likely, the diag- nosis had also been missed in case 4. This patient developed a slowly progressing ankylosis of the previously traumatized TM joint over a period of 10 months. This condition had been clinically and radiologically evaluated as being within normal limits for the acute post-traumatic stage. The pa- tient did not receive any physiotherapy and se- vere limitation of the opening of her mouth re- sulted.

Following the CT diagnosis shortly after the trauma, the other three patients received inten- sive physiotherapy, which caused a significant clinical improvement and avoided ankylosis of the TM joint in the later stages.

We believe that the coronal CT view must be performed in any case with suspected fracture in the area of the TM joints. This procedure gives more information than routine x-ray examina- tions, including tomography. The CT scanning can be done instead of the x-ray routine, sparing a high radiation dose to the patient.

REFERENCES

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2. Katzberg RW, Dolwick MF, Keith DA, Helms CA, Guralnic WC: New observations with routine and CT- assisted arthrography in suspected internal derangements of the temporomandibular joint. Oral Surg 51:569-574, 1981.

3. MacLennan WD: Consideration of 180 cases of typical frac- tures of the mandibular condylar process. Br J Plast Surg

4. North AF, Rice Y: Computed tomography in oral and max- 5~122-128, 1952.

illofacial surgery. J Oral Surg 39:199-207, 1981. 5. Horowitz I, Avrahami E, Mintz SS: Demonstration of con-

dylar fractures of the mandible by computed tomography. Oral Surg 54:263-268, 1982.

6. Eubanks RY: Fractures of the neck of the condyloid pro- cess. J Oral Surg 22:285-291, 1964.

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8. Hagan EH, Huelke DF: An analysis of 319 case reports of 39~370-372, 1981.

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