PMC8286183_01
(a) Panoramic X-ray at the first visit. A right mandibular condylar base fracture is observed. (b) A simple head X-ray at the first visit (P-A). A fracture of the right mandibular condyle and external displacement of the bone fragment are observed.
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A panoramic radiograph showed a right mandibular condylar base fracture (subcondylar fracture, Lindahl's classification) (Figure 1(a)). An X-ray of the head (P-A) showed a right mandibular condylar dislocation fracture (displacement fracture, Maclennan's classification) (Figure 1(b)).
3D-constructed CT image at the first visit. (a) Front. (b) Right side. (c) Axial. (d) 45 degrees behind to the right. CT imaging shows a right mandibular condylar base fracture and lateral dislocation of the fracture fragment. No fractures are observed except for those of the mandible. No fractures of the alveolar bones of the upper and lower jaws are also observed. No tooth fracture is observed.
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Computed tomography (CT) imaging showed a right mandibular condylar base fracture and lateral dislocation of the fracture fragment (Figure 2).
(a) Black arrow: facial artery; black triangle: sternocleidomastoid muscle. The skin incision line, the outline of the mandible, the sternocleidomastoid muscle, and the facial artery are traced using gentian violet. The planned skin incision is 0.5 mm caudally from the mandibular margin and 5 to 7 mm posteriorly from the posterior margin of the ramus to include the mandibular angle. An incision line with a total length of approximately 5 cm is made. (b) Black dotted line: platysma incision line; black square: masseter muscle. The platysma fascia is incised, approximately 2 cm subcutaneously, and the flap is raised. Once the platysma is located, it is incised to the depth of the masseter fascia such that the incision is 1 cm cranial from the mandibular margin in the anterior direction and 2 cm cranial from the mandibular margin in the posterior direction. In women, the platysma is thin, and the masseter fascia lies immediately inside the platysma. (c) A reverse warping muscle retractor is applied to the posterior margin of the ramus to gently extrude the parotid gland backward, and the masseter muscle is pulled slightly forward with the muscle retractor to expand the operative field. The periosteum is delaminated from the posterior margin of the ramus using a raspatorium, and the fracture site is located. A 0.5-mm-diameter metal wire for pulling the mandibular ramus is passed through caudally to approximately 2 cm of the fracture line. (d) By pulling the metal wire downward, the ramus is pulled sufficiently downward, and reduction is achieved. (e) After reduction, the fragment is fixed using a MatrixMANDIBLE Subcondylar Strut Plate.
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Thus, an incision line with a total length of approximately 5 cm was made (Figure 3(a)). The platysma was thin, with the masseter fascia immediately inside the platysma (Figure 3(b)). A 0.5-mm-diameter metal wire was passed through the hole (Figure 3(c)). An assistant attempted to reduce the fractured fragment by pulling the metal wire and the ramus downward (Figure 3(d)). A MatrixMANDIBLE Subcondylar Strut Plate (Depuy Synthes, Switzerland), developed for mandibular condylar fractures was used for the fixation (Figure 3(e)).
(a) Panoramic X-ray on the day after the surgery. The right mandibular condylar fracture is reduced and fixed. (b) Head X-ray (PA) on the day after surgery. The bone fragment that was displaced externally is reduced and fixed.
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The reduction and fixation were confirmed on panoramic and head X-rays (P-A) a day after the surgery (Figures 4(a) and 4(b)).