Clinical context and objective

Post-traumatic temporomandibular joint (TMJ) ankylosis induces severe functional deficits requiring complex surgical intervention. This clinical case documents the management of a 47-year-old patient presenting with bilateral bony ankylosis, with mouth opening reduced to 6 mm, following condylar fractures initially treated conservatively. The specificity of the case lay in the patient's prior enucleation of the right eye; absolute preservation of the left facial nerve and the remaining visual function was therefore paramount.

The objective of this report is to demonstrate the benefits of asymmetrical and individualized surgical planning. The authors tested the hypothesis that a dual differentiated approach — extra-oral (Al-Kayat-Bramley) with a temporal flap on the right for optimal visibility, and intra-oral with a buccal fat pad flap on the left to minimize neurological risks — would allow for effective joint release. This strategy aimed to balance the necessity of radical bone resection via Gap Arthroplasty with the anatomical constraints and functional safety imperatives specific to the patient.

Therapeutic protocol and surgical approach

This case report documents the surgical management of a 47-year-old patient presenting with post-traumatic bilateral bony ankylosis of the temporomandibular joint (TMJ), with a mouth opening reduced to 6 mm. The surgical design was individualised to address a major constraint: as the patient had an ocular prosthesis on the right side, the absolute preservation of visual function and the facial nerve on the left side was a priority.

The procedure, performed under general anesthesia, combined two distinct strategies using gap arthroplasty:

• Right side (Extra-oral approach): Use of an Al-Kayat-Bramley approach to create a 10 mm space. A temporalis muscle flap was interposed to prevent recurrence. Operative time: 74 minutes.
• Left side (Intra-oral approach): Conservative osteotomy creating an 8 mm gap via intra-oral access. A buccal fat pad flap was used as interposition material. Operative time: 94 minutes.

To release residual restrictions on mandibular movement, a bilateral coronoidectomy was performed. Bone excision was carried out using an ultrasonic cutting device to secure the surrounding soft tissues. Postoperative follow-up included early functional rehabilitation and imaging evaluations (dental panoramic and 3D CBCT reconstruction) over a 3.5-year period.

Results: Functional efficiency and long-term stability

The surgical procedure allowed for an immediate restoration of mandibular function, maintained over a 3.5-year follow-up period. The operative parameters and clinical outcomes highlight the specificities of each approach used.

From a functional perspective, the evolution of the mouth opening (inter-incisal distance) shows a major gain:

• Initial state: 6 mm (bilateral bone ankylosis confirmed by CBCT).
• At hospital discharge: 43 mm.
• 3.5-year follow-up: 38 mm, with stable occlusion and no clinical recurrence.

Qualitative observations confirm the success of the surgical strategy:

• Imaging: Postoperative CBCT validated the effective creation of interosseous spaces at the base of the condylar processes and the completion of bilateral coronoidectomies necessary for the release of muscular restrictions.
• Neurological safety: No facial nerve paralysis was observed despite the right-sided extraoral approach. On the left, the intraoral approach did not cause any sensory disturbances of the inferior alveolar or lingual nerves.
• Recovery: The patient regained normal masticatory function and a significant improvement in their quality of life without residual pain.

Note: As this is a single case report, no statistical analysis (p-values) is applicable, but the stability of the result at 42 months highlights the reliability of the Gap Arthroplasty (GA) technique combined with autogenous flap interposition.

Analysis of operative strategies

This asymmetrical approach illustrates the importance of tailor-made planning. The choice of intra-oral access on the left, although technically more demanding — with an operative time of 94 minutes compared to 74 minutes for the extra-oral route — addressed a vital priority: the safety of the facial nerve in a patient already wearing a contralateral ocular prosthesis. Clinically, this study shows that a calibrated bone resection (8 mm on the left), combined with early rehabilitation, achieves stable results without systematically resorting to the traditional wide resections of 10-15 mm.

The results of this procedure are conclusive: the mouth opening increased from 6 mm preoperatively to 43 mm in the immediate postoperative period, stabilizing at 38 mm after 3.5 years of follow-up. The use of an ultrasonic bone-cutting device ensured a secure osteotomy near the soft tissues. Regarding interposition materials, the temporal flap was preferred for wide access, while the buccal fat pad offered a flexible and accessible solution via the intra-oral approach, despite a documented tendency for volume resorption under functional pressure.

The authors point out that the literature shows no significant difference in recurrence between intra- and extra-oral approaches; success depends more on the completeness of the bone excision and the placement of a stable autogenous material. The main limitation of this report remains its unique nature, making statistical generalization impossible, but it validates the viability of the intra-oral approach for cases where extra-oral neurological risks are deemed critical.

Summary of results

Surgical treatment of this bilateral ankylosis via asymmetric arthroplasty achieved an increase in mouth opening from 6 mm to a stable 38 mm at 3.5 years. The extraoral approach (74 min) allowed for a 10 mm resection with a temporal flap, while the more complex intraoral approach (94 min) secured the facial nerve via an 8 mm resection and a Bichat flap. Bilateral coronoidectomies were essential to release persistent mandibular resistance during the procedure.

In practical terms, for the practitioner:

• Modulate the approach according to neurological risk: The intraoral approach is a strategic alternative to protect the facial nerve in patients with specific fragility (e.g., single eye), despite reduced visibility and a longer operative time.
• Perform systematic coronoidectomy: If the opening remains limited after the creation of the condylar gap, the release of muscular constraints via bilateral coronoidectomy is often the decisive step to restore kinematics.
• Systematically interpose autogenous tissue: The use of vascularized flaps (temporal or Bichat's fat pad) in the osteotomy space is crucial to prevent re-adhesions and ensure long-term functional stability.

Technical Lexicon

Gap Arthroplasty (GA): Surgical technique consisting of creating an empty space (gap) between the glenoid fossa and the ascending ramus of the mandible after resection of the ankylosed block, without immediate joint reconstruction.

Al-Kayat-Bramley approach: Modified pre-auricular skin incision allowing broad access to the temporomandibular joint and the temporal area, while protecting the branches of the facial nerve.

Temporalis muscle flap: Pedicled autogenous tissue used as an interposition material in the arthroplasty space to prevent bony re-ankylosis.

Coronoidectomy: Surgical resection of the coronoid process of the mandible, often necessary to release mandibular movements limited by fibrosis or chronic contracture of the temporalis muscle.

Buccal fat pad flap: Use of the Bichat's fat pad (buccal fat body) as a pedicled local flap to fill the joint space created during arthroplasty.

Bony ankylosis: Pathological fusion of the joint's bony components, leading to severe limitation or total loss of mandibular mobility.

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