A 27-year-old adult patient was treated by an experienced surgeon with standard two-jaw orthognathic surgery. The initial preoperative clinical examination revealed an open bite on the left side. Postsurgically the occlusion was noted to be as planned, but a left-sided open bite was again noted at 24 months (Fig. 3.1a).
The patient had a progressive facial asymmetry due to an active osteochondroma of the left TMJ, which was not diagnosed. The left condyle was significantly larger than the right side (Fig. 3.1b-d). This should have been investigated further with serial clinical examinations and an advanced imaging technique prior to jaw surgery.
The differential diagnosis of a unilateral enlarged condyle includes condylar hyperplasia (CH), hemimandibular hypertrophy (HH), hemimandibular elongation (HE), and osteochondroma. The clinical presentation may include a malocclusion with unilateral posterior open bite on the affected side, shifted dental midline and chin to contralateral side, canting of the occlusal plane, and progressive facial asymmetry
Fig. 3.1 (a) Intraoral photograph of a patient showing redevelopment of a left-sided open bite approximately 12 months after two-jaw orthognathic surgery. (b) Panoramic radiograph of the same patient after the orthognathic procedure (Note: The plate in the left mandible was removed due to a postoperative infection.) (c) 3-D reconstruction of right TMJ. The condyle appears normal in morphology. (d) 3-D reconstruction of left TMJ. Note the significantly larger and lobulated condyle, which is abnormal in shape secondary to vertical elongation of the face on the affected side. Compensatory maxillary changes can accompany the displacement of the mandibular position in long-standing cases. Although CT scans and MRI examination may be used to supplement the work-up of such condylar pathology, it may be challenging to identify the diagnosis on the basis of clinical and radiographic assessment alone. An exophytic mass and a condylar head that is lobulated suggest osteochondroma, while an enlarged and elongated condyle may suggest CH, HH, or HE. A definitive diagnosis can only be made when the clinical and radiographic features are correlated with the histopathology.
The first step in the treatment is to decide whether the enlarged condyle is still active and growing. If inactive, the patient can be treated with traditional orthognathic surgery with a realistic expectation of stability. If still active based on clinical, radiographic, or scintigraphic/PET scanning, it becomes important to make the correct diagnosis in order to determine the most appropriate surgical treatment. High condylectomy is a procedure in which 3-5 mm of the superior aspect of the condylar head is removed in an attempt to remove the cartilaginous cap. This is potentially a reasonable treatment choice to arrest active condylar hyperplasia but would not be appropriate for osteochondroma. Low condylectomy may be the treatment of choice in situations where the lesion involves the superior region of the condyle . It has the advantage of preserving a portion of the joint while avoiding the need for joint reconstruction. However, there is little long-term data to support this approach. Resection of the condyle or osteochondroma involves a complete condylectomy, and while this eliminates all growth-related pathology, it does require either autogenous or alloplastic reconstruction .