Condylar dislocation in mandibular reconstruction using a fibula free flap fixed with a reconstruction plate
Case 1
A 36-year-old male patient was diagnosed with a malignant nerve sheath tumor (MNST) of the left mandible and underwent mandibular resection. A VSP simulation surgery was then performed and CAD/CAM surgical guides were fabricated using VSP data. The mandibular bone from the right mandibular canine to the left ascending ramus was removed and reconstructed with an FFF, which was fixed with a reconstruction metal plate. The fibula was bent once and fixed on the right mandible and the left ascending ramus with a reconstruction plate (Fig. 1). Postoperative sag of left condylar segment was found in the panoramic view after surgery.
Trismus was gradually relieved after surgery, with no pain around the TMJ during mandibular function. No open bite was observed in the right posterior mandible during mastication. During the postoperative follow-up, panoramic radiographs obtained 8 months after surgery showed anterior dislocation of the left condyle with a reduction of the interocclusal distance. The patient neither complained nor showed any signs of trismus or pain in the TMJ (Fig. 2).
Case 2
A 43-year-old male patient was diagnosed with squamous cell carcinoma (SCC stage IVa) of the right mandible and underwent neck dissection including mandibular and wide resections. A VSP simulation surgery was then performed and CAD/CAM surgical guides were fabricated using VSP data. The portion of the mandibular bone from the right mandibular premolar tooth to the right condyle and TMJ was removed and reconstructed with an FFF. The FFF was fixed with a reconstruction metal plate. The fibula was bent once, connected posteriorly to the right mandibular canine, and located on the glenoid fossa with a reconstruction plate (Fig. 3).
Trismus was gradually relieved after surgery and there was no pain around the TMJ during mandibular function. No open bite was observed from the right mandibular canine to the left posterior region during mastication. During the postoperative follow-up, panoramic radiographs obtained 2 years and 1 month after surgery showed anterior dislocation of a segment of the fibula corresponding to the right condyle. The right posterior interocclusal space became narrower. The patient did not have trismus or pain in the TMJ (Fig. 4). The connection between the fibular segments 2 years later was found to be in a position similar to that observed immediately after the surgery. However, the connection between the anterior parts of the fibular segments and the mandible were severely displaced after surgery. Following radiation treatment after surgery, the metal plate became exposed and was subsequently removed. This sign may be resulted from the complication of reconstruction plate.
Condylar dislocation in mandibular reconstruction using a fibula free flap fixed with a mini-plate
Case 3
A 47-year-old male patient was diagnosed with squamous cell carcinoma (SCC stage IVa) of the left mandible and underwent neck dissection including mandibular wide resections. A VSP simulation surgery was then performed and CAD/CAM surgical guides were fabricated using VSP data prior to the main surgery. The portion of the mandible from the left mandibular molar to the left ascending ramus was removed and reconstructed with an FFF. The FFF was fixed with miniplates using two plates per connection point. Fibulae were connected to the ascending ramus of the left mandible, their anterior portions being connected posteriorly to the mandibular premolar region. The fibulae were then fixed with miniplates (Fig. 5).
Trismus was gradually relieved after surgery, with no pain around the TMJ during mandibular function. No open bite was observed from the right mandibular incisor to the right posterior region during mastication. The miniplates at the connection between the fibula and the mandible had failed and required reinforcement through additional fixation. During the postoperative follow-up, panoramic radiographs obtained 3 years and 1 month after surgery showed anterior dislocation of the left condyle. The left posterior interocclusal space had become narrower. The patient did not have trismus or pain in the TMJ (Fig. 6). The connection between the fibula segment and ascending ramus was found to be in a position similar to that observed immediately after surgery except for displacement between the anterior part of the fibula segment and the mandible. The miniplates at the connection between the fibula and the mandible had failed with widening of the inferior border. This sign may mean that this complication resulted from inappropriate height of ramus from gonial angle area to the condyle portion.
Case 4
A 61-year-old female patient diagnosed with squamous cell carcinoma (SCC stage III) of the right mandible underwent neck dissection including mandibular and side resections. A VSP simulation surgery was then performed and CAD/CAM surgical guides were fabricated using VSP data. The mandible from the right mandibular incisor to the right ascending ramus was removed and reconstructed with FFF. The FFF was fixed with miniplates, using two plates per connection point. The fibulae were connected to the ascending ramus of the right mandible, and their anterior portions were connected to the right mandibular parasymphysis and fixed with miniplates (Fig. 7).
Trismus was gradually relieved after surgery, with no pain around the TMJ during mandibular function. No open bite was observed on the left mandibular molar area during mastication. During the postoperative follow-up, panoramic radiographs obtained 1 year and 3 months after surgery showed anterior dislocation of the right condyle. The miniplates at the connection between the fibula and the right mandibular ascending ramus had failed. The connection between the fibular segment and the anterior mandibular region was found to be in a similar state as that observed immediately after surgery. The interocclusal space had not narrowed in the right posterior region, and the right mandibular condyle had become dislocated in the anterior direction. This apparently resulted from a failure to maintain the connection between the fibular segment and ascending ramus, leading to severe displacement (Fig. 8). The miniplates at bottom gonial angle area had failed the connection between the fibula and the right mandibular ascending ramus. The bottom gonial plate has been fixed only with one screw on the distal segment of the fibula. And finally, superior miniplate was broken. This sign means that lack of stability may cause the stress-related fatigue fracture of the plate and displace condylar segment.
Case 5
A 70-year-old male patient was diagnosed with squamous cell carcinoma (SCC stage IVa) of the right mandible and underwent neck dissection including mandibular and side resections. A VSP simulation surgery was then performed and CAD/CAM surgical guides were fabricated using VSP data. The mandibular bone from the right mandibular premolar to the right ascending ramus was removed and reconstructed with FFF fixed with miniplates, using two plates per connection point. The fibulae were connected to the ascending ramus of the right mandible, their anterior portions being connected posteriorly to the right mandibular incisors and fixed with miniplates (Fig. 9).
Trismus was gradually relieved after surgery, with no pain around the TMJ during mandibular function. No open bite was observed from the anterior mandible to the left molar region during mastication. Panoramic radiographs obtained 5 months after surgery during postoperative follow-up showed anterior dislocation of the right condyle. The connection between the fibular segment and the anterior mandible was bent in the posterior direction relative to its original position immediately after surgery. The connection between the fibular segment and ascending ramus could not be maintained and became bent relative to the angle of the mandible immediately after surgery. Although the interocclusal space in the right posterior region had not narrowed, the fibular segments were bent inward, while the right mandibular condyle was displaced in the anterior direction (Fig. 10).
The metal plates at the connection between the fibulae and the right mandibular ascending ramus neither failed nor became exposed. Displacement of fibular proximal segment may be associated with the fibular bone destruction of junction area. This may cause the displacement of condylar portion.
Three-dimensional simulations of mandibular reconstructions with fibula grafts
The DICOM (Digital Imaging and Communications in Medicine) files of the mandibular and fibular CT images were imported into the Mimics, version 14.0 software (Materialise, Leuven, Belgium). Then, three-dimensional (3D) images of the mandible and fibula were reconstructed. Thus, the simulated mandible was cut on the pathologic region according to the plan of operation. The 3D fibula graft was positioned at the sectioned mandibular region for mandibular reconstruction method. This simulation of the mandible reconstructed with the fibula was repeated and finally confirmed by operator. We then used stereolithographic (STL) data and a 3D printer (ProJet 360, 3D Systems, Inc., Rock Hill, SC) to manufacture rapid prototype (RP) models of reconstructed mandibles with FFF.
We manufactured a fibula cutting guide to facilitate cutting the fibula according to the surgical simulation. First, we designed the fibula cutting guide in the Mimics software. We moved the fibula bone fragments that were used to reconstruct the mandible to their original positions in the intact fibula bone. We rendered planes that would guide cutting, based on the cross sections of the fibula fragments. We used the STL data of the designed fibula cutting guide to manufacture the fibula cutting guide with the 3D printer (ProJet 3500 HDMax 3D Printer, 3D Systems, Inc., Rock Hill, SC). To facilitate placing the fibula segments into the mandible, we designed a fibula bending guide for each mandible in a reconstruction simulation. Based on the STL data of this design, the fibula bending guide was manufactured with the above same 3D printer.