Maxillary Reconstruction

Maxilla Reconstruction Anatomy

The two maxillae provide support to the midfacial skeletal and function for mastication, speech, and swallowing.

The maxilla consists of the body and its four processes: frontal, zygomatic, palatine, and alveolar. It has several articulating surfaces, which include:

• Superiorly: frontal bone
• Posteriorly: sphenoid bone, palatine and lacrimal bones and ethmoid bone
• Medially with the nasal bone, vomer
• Inferior: nasal concha
• Laterally: with the zygomatic bone.

It can be described as a hexahedrium (geometric structure with six walls) that creates a "maxillary antrum" within the central portion of the maxilla¹.

• Roof: supports the ocular globe.
• Medial wall: a lateral wall of the nasal cavity and part of the lacrimal system
• Floor: anterior portion of the hard palate and alveolar ridge
• Buttresses: 2 horizontal and 3 vertical buttresses provide projection & height
• Other walls: formation of paranasal sinuses

Maxillectomy Indications

Maxilla resections can be indicated in malignant and benign tumours of the:

• Nose
• Paranasal sinuses of the nasal cavity
• Oral cavity tumour extending into the hard palate.

Nasopharyngeal tumours are often treated with chemoradiotherapy and surgery has a more prominent role in recurrent disease.

The most common location of a tumour is the maxillary sinus, followed by the nasal cavity.  The most common malignancy is squamous cell carcinoma. Other types of tumours include:

• Epithelial: adenocarcinoma, neuroblastoma, melanoma, adenoid cystic
• Sarcoma: osteosarcoma, chondrosarcoma. rhabdomyosarcoma
• "Benign": inverted papilloma, juvenile angiofibroma, osteoma, encephalocele (soft, blue, compressible neural tube defect).

A juvenile angiofibroma typically presents in males during their 2nd decade of life. This locally invasive benign tumour can cause life-threatening epistaxis. Treatment can be ligation or embolisation of the sphenopalatine artery, but not the anterior or posterior ethmoidal arteries (as these supply the retina!).

Maxillectomy Classifications

A range of maxillary defect classification systems has been described, often within a broader category of complex midfacial defects^2-4.

Cordeiro Classification

The Cordeiro classification describes a systematic approach for the reconstruction of the complex maxillectomy/midfacial defect¹. This classifies four types of resection defects:

1. Type I Limited maxillectomy: one or two maxillary walls, excluding palate.
2. Type II Subtotal maxillectomy: maxillary arch, palate, anterior & lateral walls (lower five walls), with preservation of the orbital floor.
3. Type III Total maxillectomy: all six walls of the maxilla with orbital content preservation (IIIa) or exenteration (IIIb)
4. Type IV Orbitomaxillectomy: orbital contents, upper five maxillary walls and preservation of the palate.

This classification system is used as a communication tool, for research and for guiding maxillary reconstruction algorithms.

Brown's Classifications

Brown et al. ⁴ published a modified classification system in 2000 to help guide treatment.

1. Type I: maxillectomy not causing oronasal fistula
2. Type II: not involving the orbit
3. Type III: involving orbital adnexa with orbital retention
4. Type IV: with orbital enucleation or exenteration
5. Type V: orbitomaxillary defect
6. Type VI: nasomaxillary defect

Maxillectomy Reconstruction

Key Principles

The goal of maxillary reconstruction is to provide volume, soft tissue cover, support and return of function. This can be achieved by following key reconstructive principles:

1. Reconstruct the type of defect (skin, soft tissue, palate, orbital floor, and bony structural deficits) and its volume and surface area.
2. Obliterate dead space in the reconstructed maxillary walls with soft tissue (muscle/fat).
3. Resurface intraoral cheek, palatal, nasal lining, or external resurfacing with skin paddles. Not all surfaces are necessarily relined.
4. Rebuild required support structures, such as the maxillary arch and orbital floor, with vascularized bone or bone grafts.
5. Build walls between to recreate orbital and oropharyngeal cavities and separate the aerodigestive tract from intracranial space

Reconstruction Options

Maxillary defects are most commonly reconstructed by a flap. Free flaps should have enough pedicle length to reach the neck without vein grafting and composition to reconstruct the three-dimensional shape of the defect.

Flap reconstructive options include:

• Rectus abdominis myocutaneous: large volume with medium to large sur- face-area defects. It can be combined with a dental prosthesis. It can provide skin to reline the maxillary sinus and repair the palatal defect.
• Radial forearm flap: Large surface area with small to medium volume defects. These can be fasciocutaneous or osteocutaneous.
• Pedicle temporalis muscle: can be transposed into the mouth, usually in older patients with contraindications for free flap surgery, not used for palatal reconstruction. It has a short arc of rotation.
• Free fibula: can be used to close the palatal defect to prevent nasal regurgitation, can also accept osseointegrated implants due to the good quality of bone stock associated with this flap.
• DCIA Flap: allows for dental rehabilitation.

Some patients require additional procedures in addition to the free flap, such as:

• Non-vascularised bone grafts from split ribs, split calvarium, iliac crest.
• Local flaps, for example, a lip switch flap if a lip resection is also performed.
• Prostheses can be used for obturation but are preferred for smaller defects.

Palatal obturators can adequately restore missing maxillary dentition as well as prevent oronasal leakage of air, liquids, and foods. They have the advantage of being removable, which permits visualization of the maxillary cavity for tumour surveillance. Prosthetic retention can be difficult or impossible in sizable defects, particularly when there are few teeth to stabilize the prosthesis.

Based on Defect Classification

Type I Limited Maxillectomy:

• Small volume, large surface-area defect
• Consider nonvascularized bone grafts & radial artery forearm flap.

Type II Subtotal Maxillectomy:

• Medium volume, large surface-area defects
• Consider radial artery forearm flap (can reline palatal mucosal surface and nasal floor when folded over)

Type IIIA Total Maxillectomy with Sparing of Orbital Contents

• Medium-large volume and medium-large surface-area defects
• Require orbital floor reconstruction (bone grafts) and palatal reconstruction (the cutaneous aspect of a flap or obturator)

Type IIIB Total Maxillectomy with Orbital Exenteration

• Large volume and large surface-area defects
• Requires reconstruction of nasal lining (medial maxilla wall) & external defect with multiple skin islands  
• If the external skin is intact, a rectus-free flap with a skin island is used to close the palate, a second skin island to restore the lateral nasal wall, third skin island can be used to provide closure of the external skin deficit if necessary.

Type IV Defects: Orbitomaxillectomy

• Large volume and surface-area defects with an intact palate
• Consider rectus abdominis flap to obliterate dead space and provide external skin resurfacing if needed.

Maxilla Reconstruction Algorithm

Flashcards