Key points
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Comorbid temporomandibular joint (TMJ) arthropathies and dentofacial anomalies pose complex diagnostic and treatment planning dilemmas.
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Surgical goals of combined reconstruction include: symptomatic and functional relief of an end-stage TMJ arthropathy, functional occlusion, and esthetic facial harmony.
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Simultaneous correction of concomitant TMJ arthropathies and dentofacial anomalies requires diligent presurgical sequencing and planning, to achieve planned surgical movements.
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Planned surgical movements are limited by the patient’s soft tissue envelope and must consider the arc of rotation necessary for mandibular opening.
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Use of patient-specific TMJ alloplasts requires precision during alignment and fixation, as intraoperative modifications are not possible. Orthognathic movements may need to be altered, requiring intraoperative hand-bending of stock hardware.
Abbreviations
| IOS | intraoral scan |
| PSI | patient-specific implant |
| TJR | total alloplastic joint replacement |
| TMJ | temporomandibular joint |
| TMJA-DFAM | TMJ arthropathies and dentofacial anomalies with malocclusion |
Introduction: Nature of the problem
Patients may present with unilateral or bilateral temporomandibular joint (TMJ) arthropathies and concomitant dentofacial anomalies, severely impacting: mastication, speech, respiration, and deglutination. TMJ arthropathies are characterized by mandibular dysfunction (ie, hypomobility, hypermobility, and instability) and may or may not present with pain.
Patients typically present in 1 of 3 ways
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Patient presents with predominant chief complaint of a TMJ arthropathy, and is unaware of the impact of the co-existing dentofacial anomaly.
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Patient presents with predominant chief complaint of a dentofacial anomaly with dental malocclusion and is unaware or asymptomatic at degenerated TMJ.
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Patient is symptomatic at dysfunctional TMJ and is aware and bothered by coexisting dentofacial anomaly with malocclusion.
Patient education and understanding of the complexities associated with concomitant TMJ arthropathies and dentofacial anomalies with malocclusion is paramount, as extensive surgical reconstruction, including TMJ total alloplastic joint replacement (TJR) with simultaneous orthognathic surgery, may be indicated in effort to achieve asymptomatic, stable functional mandibular movements that end in repeatable, balanced occlusion. ,
Surgical technique
Preoperative planning
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Initial questions to consider in patients planned for combined TJR and orthognathic surgery. The following questions determine subsequent presurgical timeline and surgical planning sequence:
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Is a unilateral or bilateral TJR indicated?
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If unilateral, a contralateral sagittal split osteotomy (vs vertical ramus osteotomy) may be indicated.
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Is a single-stage or 2-stage TJR planned?
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Single-stage TJR is defined as simultaneous condylectomy, fossa osteoplasty, and insertion of TJR prostheses
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Two-stage TJR refers to 2 separate procedures:
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Gap arthroplasty, including condylectomy, is performed. Obtain postprocedural CT (or cone-beam computed tomography [CBCT]) to be used for fabrication of TMJ prostheses
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More than 3 months later: Return to operating room for necessary osteoplasty and insertion of TJR prostheses performed
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If 2-stage, open arthroplasty and condylectomy completion date will determine timeline for obtaining final CT scan to be used for fabrication of alloplast(s).
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Are presurgical orthodontic movements ongoing?
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When is the anticipated end to active presurgical movements?
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Recommend orthodontic-latency of ∼4–6 weeks before obtaining CT and intraoral scan (IOS) to be used for fabrication of alloplast(s).
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Presurgical virtual surgical planning of both the TJR and orthognathic movements will be completed at the same time. ,,, When planning bilateral TMJ TJR, planning starts in the maxilla, achieving the ideal, optimized maxillary position before establishing occlusion. The mandibular prostheses’ positions are determined by the maxillary position and occlusion.
Manufacturer’s lead time for fabrication of the TMJ alloplast(s) determine surgical scheduling. Contemporary lead time is 12–16 weeks. Patient-specific implants (PSIs) for Le Fort and/or genioplasty have a shorter lead time and can be fabricated from updated IOS 3–4 weeks before surgery.
Prep and patient positioning
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The TJR component of the procedure is sterile and should follow aseptic technique
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Recommend use of adhesive coverings and drapes to seal off the oral cavity.
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Prep with betadine, emphasis to cleaning external auditory canal
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While the preauricular and submandibular incisions are open: any time the oral cavity is accessed, a sterile drape should be placed on top of all sterile instruments, and effort should be made to prevent saliva from contaminating the extraoral incisions.
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The orthognathic component of the procedure is clean contaminated
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Prep of the oral cavity with betadine and/or chlorohexidine are recommended.
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Surgical approach
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Preauricular and (modified) submandibular incisions are recommended for adequate access for insertion and fixation of glenoid fossa alloplast and the condylar component of the alloplast
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Surgeon-dependent preference on which incision to perform first
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Surgeon-dependent selection of modifications to preauricular incision, including endaural incision, temporal extension, and modified endaural ( invisicion )
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Traditional vestibular incisions are used to access the maxilla, mandible, and genial region.
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Care is taken to avoid subperiosteal dissection that directly communicates with the TMJ alloplast(s).
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Surgical procedure steps listed
Surgical steps for bilateral temporomandibular joint total joint replacement and Le Fort osteotomy ± genioplasty
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Prepping and sterile draping is performed, isolating the field. See Fig. 1 A, B .
Fig. 1 ( A , B ) Photo of prepped and draped patient. Note the adhesive seal over nose and mouth.
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The selected preauricular incision (or modification) and submandibular incisions are marked.
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Administration of dilute epinephrine subcuticularly to help with hemostasis and hydro-dissection.
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See Clayton M Davis’s article, “ Autogenous and Alloplastic Reconstruction of the Temporomandibular Joint ,” in this issue.
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Completion of condylectomies, fossa osteoplasty, coronoidectomies, and fixation of glenoid fossa prosthesis components. See Figs. 2–15 .
Fig. 2 ( A ) Modified submandibular exposure. ( B ) Closer view of right ramus exposure via submandibular incision.
Fig. 3 ( A ) External view of cutting and fixation guide, sitting flush along the entire lateral aspect of the mandibular ramus ( B ) Endoscopic confirmation of adequate adaptation of the right condylar cutting and fixation guide, at the level of the sigmoid notch.
Fig. 4 Visual confirmation of appropriate adaptation of condylar cutting guide along the right mandibular angle.
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