Custom made zygomatic arch and total alloplastic temporomandibular joint after gun shot injury: A case report

Abstract

Gunshot wounds to the face result in substantial loss of bone and soft tissues, which leads to significant functional and aesthetic deficits. Management of facial gunshot wounds remains controversial, especially the timing of surgical treatment and the reconstructive techniques. We present a case of facial gunshot wound to the left temporomandibular joint (TMJ) region and adjacent structures that was treated by total alloplastic TMJ reconstruction 18 months after the initial injury.

Highlights

  • facial gunshot wounds may result in significant head and neck deformities.

  • Complex reconstruction following these injuries is a huge challenge.

  • Patient -matched prostheses provides optimum reconstruction.

Introduction

Involvement of the craniofacial skeleton, airway compromise, intracranial and vascular systems and psychological issues makes facial gunshot wounds (GSWs) very complex [ ]. Emergency care of these injuries focuses first on basic principles of trauma resuscitation, with priority attention given to the airway status, followed by haemodynamic resuscitation and general patient assessment to exclude concomitant injuries.

In general, surgical management of facial GSWs is generally into 3 stages debridement, fracture stabilization and primary closure; reconstruction of hard tissues (provided soft tissue coverage is adequate) and finally rehabilitation of the oral vestibule, alveolar ridge and secondary correction of residual deformities. Immediate reconstruction of these defects is often complicated by tissue ischaemia, necrosis, compromised soft tissues and infection [ ].

We present a case of facial gunshot wound to the left temporomandibular joint (TMJ) region and adjacent structures that was treated by total alloplastic TMJ reconstruction 18 months after the initial injury.

Case report

A 40-year old male presented to the maxillofacial and oral surgery outpatient clinic of the CHBA (Johannesburg, South Africa) complaining of the inability to open his mouth and chew. He provided a history of having suffered a gunshot wound to his left face 18 months previously. He subsequently had damage control surgery which included neck exploration and ligation of the left external carotid artery. On presentation, the patient was fully conscious and responsive. Examination revealed scarring on the left neck and in the left preauricular region. He also had partial paralysis of the left facial nerve ( Fig. 1 A &B)). He had hearing loss on the left ear and was wearing hearing aids. Patient was unable to open his mouth beyond 5 mm. Intra-oral examination showed deranged occlusion and deviation of the mandible to the left side and few missing teeth ( Fig. 2 ).

Fig. 1
A & B: clinical photos of the patient showing the fall out of the facial nerve and lacerations.

Fig. 2
Intraoral photo shows deranged occlusion, open bite, and deviation.

Conventional and panoramic radiographs showed comminuted fractures and indistinct deformity on the left zygomatic arch and mandibular condylar head region. This was confirmed on CT SCANS: left temporomandibular joint had very comminuted fracture and there was missing bone from the condylar head, fossa, and zygomatic arch ( Fig. 3 ). No intracranial pathology was noted.

Fig. 3
3D reconstruction of the facial bones showing comminuted TMJ fractures and zygomatic arch/temporal bone defects.

The patient went through conservative treatment of the condylar injury by arch bar and elastic to guide the mandible and stabilize the occlusion. It did work for few weeks and then relapsed.

Surgical planning consisted of reconstruction of debridement of the comminuted segments followed by zygomatic arch reconstruction and total joint replacement with Zimmer Biomet Microfixation TMJ Replacement System (Biomet Microfixation, Jacksonville, FL, USA) custom prostheses ( Fig. 4 ). The definitive fossa component was constructed of two materials, titanium alloy for the zygomatic arch/temporal bone defect, and secured to it with titanium screws; The articulating fossa component made from ultra-high molecular weight polyethylene (UHMWPE) polymer, titanium alloy for the ramus component, and Co–Cr–Mb for the articulating condylar head. The planning included a surgical guide and screw lengths labels.

Fig. 4
3 D images showing preoperative image and Virtual Surgical Planning for the custom prostheses.

Arthroplasty was performed via combined preauricular and Risdon incisions. Using the surgical guide, the osteotomy cuts were completed for the ramus, coronoid, remaining condyle, and zygomatic arch edges). The zygomatic arch and fossa component templates were used to check the stability and accuracy of the osteotomy cuts. Fixation screws was drilled in as per the planned length to avoid violation of the air cells posteriorly. The template for the mandibular component was placed and fixated in position. The condyle fossa relation was checked and finalized. Once satisfied, the template of the fossa component removed and the definitive fossa component placed and secured ( Fig. 5 ). The definitive mandibular component was secured in place after removal of the template ( Fig. 6 ). The mouth opening and the occlusion were check in between while maintaining sterility of the surgical field. An intraoperative mouth opening of 40 mm maximum interincisal opening (MIO) was achieved, with repeated optimum occlusion. Post-operatively, he was placed on light elastics, discharged after 48 hours and referred for physiotherapy for 3 months. MIO at 1-year follow-up was 40 mm, occlusion was intact and the patient had optimal function ( Figs. 7 and 8 ). The patients has not complained of any pain or discomfort in the affected joint, and reported to be functioning optimally. Also, no signs of implant failure were noticed on the follow-up, clinically and radiographically ( Fig. 9 ).

Mar 21, 2021 | Posted by in Oral and Maxillofacial Surgery | Comments Off on Custom made zygomatic arch and total alloplastic temporomandibular joint after gun shot injury: A case report
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