Abstract
Current techniques in management of end stage pathology of the temporomandibular joint (TMJ) include the use of alloplastic joint reconstruction. A polyethylene glenoid fossa prosthesis is a necessity of this treatment as it provides a stable platform for function of the metal alloy condylar head. Additionally, the fossa prosthesis limits superior and posterior movement of the reconstructed joint which prevents complications such as migration of the condylar prosthesis into the middle cranial fossa and ear, ankylosis, and pain.
When a pathologic process affects the glenoid fossa alone, alloplastic joint reconstruction becomes a less desirable treatment option. Lack of osseous structure along the temporal bone and zygomatic arch can impact the surgeon’s ability to fixate a glenoid fossa prosthesis. Additionally, resection of an uninvolved condylar head in situations where there is no advanced pathology would provide a functional solution, but may be overly aggressive and potentially unnecessary.
The following is our experience with utilizing a pedicled temporal osteomuscular flap to reconstruct an acquired defect of the glenoid fossa in a 42-year-old male with a diffuse-type tenosynovial giant cell tumor. In this case the mandibular condyle was not affected by the pathology.
Highlights
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Management of temporal bone defects with preserved mandibular condyle.
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Non-alloplastic reconstruction of the temporomandibular joint.
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Management of post-ablative defect of the glenoid fossa.
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What to do when an alloplastic temporomandibular joint is not an option.
1
Introduction
Giant cell tumors (GCT’s) of the skull are a rare entity. When diagnosed the temporal bone is the most common location [ , ]. GCT’s of the skull present equally in men and women, with the average patient presenting in the 2nd or 3rd decade of life [ , ]. Various treatment options are reported in the literature which include surgical resection, curettage, subtotal resection with adjuvant radiation therapy, interferon alpha, denosumab, calcitonin, bisphosphonates and intralesional steroids [ ]. The overall recurrence rate for treatment of GCT’s is approximately 17.6%; segmental resection carries the lowest recurrence risk at roughly 4.3% [ ]. Interferon, denosumab, calcitonin, and steroids are treatment options that may minimize morbidity but should be evaluated on a case-by-case basis as they may require some adjuvant surgical treatment for cure [ ]. This patient presented with a GCT affecting the glenoid fossa without involvement of the adjacent condylar head. The goal of treatment was to create a reconstruction that would withstand the load of the mandibular condyle during function, provide a stopping position for the joint, allow for freedom of movement, maintain the patient’s occlusion, minimize pain, and to provide a cosmetically acceptable result. Reconstructive options for this indication are limited but include autogenous bone grafting or custom alloplastic implants. This is our experience managing a post-ablative glenoid fossa defect utilizing a pedicled rotational temporal osteomuscular flap.
2
Case presentation
A 42-year-old male presented to the department of neurosurgery (NGY) with an indurated swelling of the left temporal region, left sided facial numbness, tinnitus, and intermittent headaches. The swelling had been progressing slowly for 5 years.
CT scans were obtained which demonstrated a mixed radiodense/radiolucent lesion with well-defined scalloped borders originating in the left temporal bone ( Fig. 1 A–D). A laboratory workup showed no evidence of hypercalcemia or hyperparathyroidism. Core needle biopsy of the lesion was completed which showed a giant cell rich neoplasm. NGY elected to proceed with subtotal excision of the lesion and Oral & Maxillofacial Surgery (OMS) was consulted for management of the planned ablative defect of the glenoid fossa.
2.1
Surgical plan
Surgical access to the lesion was obtained via a hemicoronal flap with a planned craniotomy for access to the left temporal bone and excision of the giant cell tumor ( Fig. 2 ). This resection was to include complete removal of the glenoid fossa and approximately 50% of the ipsilateral zygomatic arch. The mandibular condyle was not involved by the primary tumor. OMS elected to reconstruct the glenoid fossa and zygomatic arch utilizing a pedicled temporal osteomuscular flap. This required both extension of the planned craniotomy superiorly to harvest the necessary bone and modification of the dissection approach to preserve a portion of the temporalis muscle to maintain flap vitality.
To accurately predict the bone necessary for reconstruction, OMS utilized virtual surgical planning (VSP). The VSP allowed prediction of a harvest site outside tumor margins, a reproducible resection position of the zygomatic arch, and created a surgical guide for the internal surface of the skull to accurately shape a bone flap which would correspond to the planned ablative defect.
2.2
Surgery
After a hemicoronal flap was elevated, intraoperative navigation was utilized to determine the tumor position under the temporalis muscle. A temporal craniotomy was preformed superior to this taking into account the additional bone for glenoid fossa reconstruction.
Once the bone flap was released from the dura, dissection proceeded through the temporalis muscle protecting a portion anteriorly to provide vascular supply. The muscular pedicle was then dissected medially from the skull which allowed for access to the tumor and free movement and rotation of the flap ( Fig. 3 A ). The blood supply was maintained by evidence of bleeding of the bony flap margins.
