Treatment of the Temporomandibular Joint Ankylosis with a Customized Prosthesis in a Single Stage: The Use of 3D Cutting Guides and Virtual Surgical Planning

Abstract

Background

Ankylosis of the temporomandibular joint (TMJ) is a debilitating condition and disabling as a result of craniomandibular fusion, which can result in trismus, pain and a poor quality of life. Current management includes interposition arthroplasty, gap arthroplasty, and reconstruction. Traditionally, the joints are reconstructed with pre-made prostheses (in stock), or the procedure is performed in two steps; with a computerized tomography scan, its design is observed between the respective and reconstructive procedures.

Study Design

A technical note about the customization management of ankylosis of the temporomandibular joint.

Objective and Methods

Describe a modification of technique using 3D surgical cutting and positioning guides digitally created to help determine the position and dimensions of the osteotomies as an auxiliary tool in the management of TMJ ankylosis, enabling the installation of personalized prostheses in a single stage.

Conclusion

This technique has the advantage of allowing the installation of customized TMJ prostheses in a single stage, allowing greater predictability, less surgical time and less morbidity, in addition to being relatively simple and can be easily picked up by young surgeons.

Ankylosis of the temporomandibular joint (TMJ) is a condition in which the joint surfaces are fused either by bone or fibrous tissue, causing a debilitating condition that can interfere with speech, chewing, appearance, hygiene, and normal life activities, in addition, it may cause dentofacial deformity and asymmetry [1–4]. The present work aims to present a technical note on how to use a prototyped 3D guide for the treatment of temporomandibular ankylosis.

Computer-Aided Planning

The DICON files from the face computed tomography (CT) were imported into the virtual surgical planning software (Dolphin 3D, Chatsworth, USA), which generated the three-dimensional data in STL file format. Then, in the software Blender 3D (Blender Foundation, Amsterdam, the Netherlands), osteotomies were simulated, and virtual surgical guides were modeled, which were based on the bone surface of the three-dimensional reconstruction.

3D Positioning and Cutting Guides

The digitally modeled cutting and positioning guides were exported for aluminum machining. The cranial guide had the following characteristics: adaptation to the zygomatic arch and the lateral face of the ankylotic block, presenting, in the upper portion, four holes for 1.5 mm screws that coincide with the definitive cranial component of the future articular prosthesis and a lower rod that prevents the rotation of the guide during installation, and offers an intermediate space which will determine the height and extent of the upper limit of the osteotomy (Fig. 1). Likewise, the mandibular guide design allows anatomical adaptation to the lateral face of the mandibular ramus with eight holes for 2.0 mm screws that match the holes in the definitive mandibular component. The upper limit of this guide was determined after the identification of the mandibular foramen, aiming to preserve the lower alveolar nerve (Fig. 2).

Fig. 1.

Cranial surgical guide drawing based on the bone surface of three-dimensional reconstruction. An upper shaft with four 1.5 mm screws (arrow) and a lower shaft (asterisk) guide the height and extent of the osteotomy, which must be completed with a minimum distance of 0.5 mm from the external auditory canal

Fig. 2.

Mandibular surgical guide drawing based on the bone surface of three-dimensional reconstruction of the mandible ramus (arrow). The lower limit of the osteotomy in the ankylotic block (asterisk) should be performed with a minimum distance of 10 mm from the foramen of the mandible. This minimizes the risk of neural damage

Surgical Technique

Prior to the surgical approach, the patient with TMJ ankylosis was submitted to prophylactic embolization of the ipsilateral maxillary artery, as described by Hossameldin et al. [4]. Subsequently, after nasotracheal intubation using nasofibroscopy, the joint was accessed through an endaural and submandibular incision with dissection by planes until exposing the ankylotic block and the mandible ramus[1]. After exposure, the prefabricated cutting guides were installed on the zygomatic arch and the mandibular ramus, and temporarily fixed with screws (Fig. 3). The guided osteotomies were performed with piezoelectric saw, and then the ankylotic block was carefully removed. This was followed by the planing of the mandibular fossa for a correct adaptation of the cranial component of the definitive prosthesis. The definitive components were then placed on the base of the skull and in the mandibular ramus and fixed in the position previously determined by the guides (Fig. 4). There was no need for maxillomandibular block, avoiding transoperative communication with the oral cavity.

Fig. 3.

Intraoperative view of the cutting guides and positioning of the cranial and mandibular components, enabling the reproduction of the planned cuts virtually

Fig. 4.

Intraoperative view and post-operative computed tomography with three-dimensional reconstruction of the customized prosthesis installed in a single phase with the aid of cutting guides

The use of cutting guides and 3D positioning proved to be effective to aid the treatment of temporomandibular joint ankylosis with a total custom prosthesis in a single stage, allowing greater predictability, less surgical time and less morbidity.

Declarations

Conflicts of interest

We have no conflicts of interest.

Ethics Approval

Ethics approval was not required. The patient has permitted the images use.