Resecting neoplasms involving the infratemporal space has a high risk of damaging critical nerves and vessels, in addition to joint form and function. The purpose of this study was to introduce a novel approach to lesions medial to the condyle, which comprises a condylectomy with anterior displacement of the condyle. The indications evaluated using digital surgical simulation, the critical surgical technique, and the preliminary clinical effects are presented here. Five cases underwent this approach between January 2006 and December 2014. The common characteristics of the five masses were (1) that they were non-malignant neoplasms involving the posterior-medial region of the condyle; (2) the upper and lower borders were between the skull base and the lingula, while the anterior border did not exceed the coronoid process. All masses were resected successfully with no damage to any critical nerves or vessels. The average follow-up period was 29.8 months (range 6–56 months). There was no recurrence, secondary deformity, or facial paralysis. The average mouth opening improved from an original 27 mm to 34 mm after surgery. The condyles were well fixed, with no resorption, as shown on computed tomography scans.
Neoplasms originating in the temporomandibular joint (TMJ) may extend into the infratemporal space, leading to difficulty in determining the boundary and an increased risk of damage to critical nerves and vessels. The resection of neoplasms in this region can cause TMJ dysfunction and secondary dentomaxillofacial deformity. The pre-auricular approach (zygomatic, coronal, or condylar approach), submandibular approach, and anterior approach (intraoral or nasopharyngeal approach) are commonly used to expose the infratemporal space. The latter two approaches have disadvantages including extensive damage, excessive bleeding, limited surgical exposure, and a long operation time.
This study group has previously performed an approach involving rotation of the osteotomized condyle, developed to remove an encapsulated benign tumour in the deep lobe of the parotid that had extended into the infratemporal space. This approach is less invasive, does not involve opening the TMJ capsule or releasing the lateral pterygoid muscle attachment to the condyle, and thus could preserve the TMJ structure and function. However, due to the limitation of the disc, the condyle could only be rotated with little translocation. This approach could not be used to expose relatively large masses, especially those involving the infratemporal space and the skull base. The authors considered that a condylectomy with anterior displacement of the condyle would allow a wider surgical field medially, because the forward movement of the condyle has no bony obstacles.
Computer-assisted design (CAD) has been revolutionary in the performance of precise resection and reconstruction. Is it possible to use digital surgical simulation to select the surgical approach? What is the critical technique of this approach? And will this approach affect TMJ function or lead to dentomaxillofacial deformity? To answer these questions, the cases of five masses treated using this novel approach between January 2006 and December 2014 were reviewed.
Materials and methods
The regional ethics review board of the study hospital in Shanghai, China approved this study, which was performed in accordance with the Declaration of Helsinki on medical protocol and ethics.
This was a retrospective study. Five patients with TMJ masses involving the infratemporal fossa underwent resection via condylectomy with anterior displacement of the condyle. General data for the patients who underwent this approach are listed in Table 1 . The initial diagnosis was made on the basis of clinical characteristics, as well as computed tomography (CT) and magnetic resonance imaging (MRI) examinations.
|No.||Sex||Age, years||Symptoms||MIO||Diagnosis||Follow-up, months||Deformity||Recurrence||Facial paralysis|
|1||F||52||Swelling, noise in the TMJ region||35||42||SC
(30.5 × 19.5 × 17 mm)
|6||No||No||Minimal weakness of the ipsilateral brow movement|
|2||F||24||Swelling, pain, limitation of mouth opening||10||28||Vascular malformation
(40 × 35 × 30 mm)
|3||M||56||Swelling, pain, noise in the TMJ region||30||32||SC
(35 × 24 × 27 mm)
|4||F||47||Swelling, pain, limitation of mouth opening||28||37||PVNS
(25 × 12 × 8 mm)
(47 × 33 × 25 mm)
The five cases included three cases of synovial chondromatosis (SC), one case of pigmented villonodular synovitis (PVNS), and one case of vascular malformation ( Table 1 ). The three cases with SC showed a large number of free bodies located in the superior joint space, with an extension into the infratemporal space. The case of PVNS involved the retrodiscal area, medial capsule, and the articular surface, causing a small perforation of the skull base. In the remaining patient, the vascular malformation was located medial, posterior, and lateral to the condyle, with involvement of a large part of the retrodiscal area and joint capsule. The possibility of malignancy could not be excluded before surgery in the case with vascular malformation.
Computer-assisted surgical design
The CT data of all patients were transferred into Mimics 15.0 software (Materialise, Leuven, Belgium) for three-dimensional (3D) reconstruction before surgery. The size of the neoplasm, its location, and its relationship with the adjacent anatomical structures were evaluated ( Figs 1A and 2A ). Digital surgical simulations were performed, including the design of the surgical approach and the lines of bone osteotomy ( Figs 1B and 2B ).