Abstract
Temporomandibular joint (TMJ) reconstruction may be required in complex cases in which there are additional mandibular or zygomatic arch defects. The reconstructive options include autogenous tissue, alloplastic material, or combinations of these. The authors describe 4 cases in which TMJ reconstruction was performed with TMJ Concepts customized joint prostheses. The prosthetic components were designed to restore major defects in the zygomatic arch and the mandibular ramus and body, including one case in which the mandibular component was used to restore total mandibular continuity. The prosthetic components used in these cases provided excellent anatomical reconstruction, and were a viable treatment option in cases in which the pathological process made autogenous grafts unsuitable. The prostheses have been functioning for up to 6 years. In one case a revision operation was required because the lack of a pterygomasseteric sling resulted in the condyle dropping out of the fossa. The authors’ clinical experience with these cases suggests that a customized prosthesis combined with TMJ reconstruction can be a reliable treatment alternative for bridging complex, major maxillo-mandibular defects.
Most cases of temporomandibular joint (TMJ) reconstruction require replacement of the joint, but there are occasions when the reconstructive surgeon must also consider the reconstruction of significant associated mandibular defects. Faced with this situation, the surgeon has to choose between autogenous, or alloplastic (prosthetic) reconstruction, or a combination of these techniques. Autogenous options include free costochondral grafts , and vascularized bone grafts . Prosthetic TMJ reconstruction in cases with major mandibular defects or other abnormal anatomy usually require custom-made devices. A number of options are available, including TMJC (TMJ Concepts Inc., Ventura, CA, USA), Biomet, Biomet Microfixation, Jacksonville, FL, USA, and TMJ Implants, Golden, CO, USA. The TMJC TMJ reconstruction device is a computer-assisted designed and manufactured (CAD CAM) prosthesis constructed on a stereolithic three-dimensional (3D) model fabricated from the patient’s computed tomography (CT) scan data. The fossa component consists of an ultra-high molecular weight polyethylene (UHMWPE) articulating surface attached to a commercially pure titanium mesh base. The mandibular component is made of machined alloyed titanium with a condylar head of chrome–cobalt–molybdenum (Cr–Co–Mb) alloy. For a detailed description of the construction method see M ercuri . The fossa component is attached to bone at the root of the zygomatic arch using titanium screws, while the mandibular component is similarily attached to the lateral aspect of the ramus/body of the mandible. TMJC TMJ reconstruction prostheses have been in use for over 15 years and have demonstrated satisfactory long-term reliability with no evidence of foreign body reactions or material breakdown .
Most TMJC devices that have been installed over this period have been straightforward local TMJ reconstructions. More recently, they have been used to bridge increasingly large mandibular defects, for example in a case with hemifacial microsomia .
The authors present 4 cases in which the TMJ was constructed, or re-constructed, in combination with simultaneous bridging of large mandibular defects.
Case 1
A 21-year-old woman presented who had suffered from an osteomyelitis of the right mandibular ramus and angle since the age of 6 years. Previous treatment modalities had been ineffective with persistent, ongoing intermittent pain and swelling of the cheek. Eventual TMJ ankylosis required surgical intervention. Autologous bone reconstruction was rejected, in view of the underlying pathologic process affecting much of the native mandible. It was decided to release the ankylosed TMJ and replace it with a joint prosthesis in combination with much of the hemimandible. The radiologic examination suggested that resection from the joint area to the mental region would be required to clear the diseased bone. This resection was planned on the patient’s 3D model, and a TMJC prosthesis was designed to bridge the significant mandibular defect ( Fig. 1 a) .
The teeth posterior to the planned resection line were extracted 3 months prior to alloplastic reconstruction in order to secure intact oral mucosa over the eventual prosthesis.
Resection of the body and ramus of the mandible was carried out through three small incisions: preauricular, subangular, and submental. Following subperiosteal dissection, release of the ankylosed joint and cutting the anterior bone, the pathologic bone was delivered through the submental incision ( Fig. 1 b). The fossa component was installed through the preauricular incision, and the condylar-mandibular component through the submental exposure ( Fig. 2 ).
The patient was discharged after 48 h, and was allowed immediate jaw-function with no postoperative complications. The prosthesis has functioned well with an interincisal opening of 38 mm and excellent occlusion. There has been no evidence of any persisting inflammatory process ( Fig. 3 ).
Case 2
A 33-year-old woman with Goldenhar syndrome required reconstruction of missing skeletal components and facial soft tissue on the right side. Previous orthognathic surgery had been ineffective in correcting the deformity ( Fig. 4 ). A further bimaxillary osteotomy was performed, and a new CT scan obtained. From this a 3D model of the facial skeleton was produced and a TMJC prosthesis was made that incorporated the missing zygomatic arch as part of the titanium base of the fossa component. The mandibular component was fabricated as a mirror image of the left side ( Fig. 5 ).
Simultaneous soft tissue transfer was carried out in conjunction with the TMJC insertion. An extended preauricular incision was used to explore the facial nerve in a centripedal direction from the peripheral branches proximally to beyond the distorted auricle. The TMJC components were installed with a perfect fit to the underlying bony surfaces. Soft tissue to cover the prosthesis was provided by a deep inferior epigastric perforator (DIEP) free vascularized flap. A temporary traction paresis of the lower branches of the facial nerve resolved within 6 weeks. Following primary healing, the DIEP flap was reduced and refashioned on three occasions before a satisfactory final appearance was achieved.
The patient has functioned with her TMJC prosthesis for 4 years with an interincisal opening of 30 mm ( Fig. 6 ).
Case 2
A 33-year-old woman with Goldenhar syndrome required reconstruction of missing skeletal components and facial soft tissue on the right side. Previous orthognathic surgery had been ineffective in correcting the deformity ( Fig. 4 ). A further bimaxillary osteotomy was performed, and a new CT scan obtained. From this a 3D model of the facial skeleton was produced and a TMJC prosthesis was made that incorporated the missing zygomatic arch as part of the titanium base of the fossa component. The mandibular component was fabricated as a mirror image of the left side ( Fig. 5 ).
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