Midface reconstruction is a complex surgical field dedicated to repairing defects in the central part of the face, primarily involving the maxilla. This comprehensive guide will delve into the various types of midface defects and the specialized techniques surgeons employ to restore both function and aesthetic appearance, offering a clear overview for students and those new to the topic.

Understanding Midface Reconstruction: Defects and Techniques

The midface, centered around the maxilla, is a critical area for facial structure and function. The maxilla itself can be conceptualized as a six-walled geometric box, encompassing the orbital floor (roof), the hard palate and alveolar ridge (floor), and the medial walls forming the nasal passages. This central bone houses the maxillary antrum, supports the cranial base, and features horizontal and vertical buttresses that define facial width, height, and projection. Overlying soft tissues, including muscles of facial expression and mastication, also attach to the maxilla, contributing to individual appearance and essential functions.

Goals of Midface Reconstruction

The primary goals of midface reconstruction are both functional and aesthetic, aiming to significantly improve a patient's quality of life. Key objectives include:

Wound closure: Ensuring complete and secure covering of the defect.
Barrier restoration: Creating a strong separation between the sinonasal cavity and the anterior cranial fossa to prevent complications.
Oral and sinonasal separation: Maintaining distinct environments for eating/speaking and breathing.
Orbital support: Sustaining the orbital contents and maintaining the correct position of the ocular globe.
Oral continence: The ability to retain food and liquids in the mouth.
Speech and mastication: Restoring clear communication and effective chewing.
Eyelid position: Avoiding complications like ectropion (eversion of the eyelid).
Nasal airway patency: Ensuring an unobstructed breathing passage.
Facial appearance: Achieving symmetry, natural contour, minimizing scars, and proper eyelid positioning.

Why Midface Reconstruction is Necessary

Midface defects most commonly arise from oncologic surgery, particularly after the removal of squamous cell carcinoma of the oral cavity or sinonasal mucosa. Other tumors, such as minor salivary gland tumors and adenocarcinoma, can also necessitate extensive resections. Beyond cancer treatment, high-energy trauma is another significant cause, often requiring concurrent reconstruction of other craniofacial injuries. Over the years, advancements like rigid internal fixation and osteocutaneous free tissue transfer have greatly improved reconstructive outcomes.

Classifying Maxillectomy Defects: A Guide for Students

To effectively reconstruct the midface, a clear understanding of the defect's extent is crucial. An established classification system, based on the amount of maxillary bone resected, guides surgical decisions. This approach ensures consistent and reliable results, even for very large and complex defects.

Type I: Limited Maxillectomy Defects

Characteristics:

Involve one or two walls of the maxilla, typically the anterior and medial walls.
Crucially, both the palate and orbital floor remain intact.
Resection may include overlying soft tissue, skin of the cheek, and sometimes parts of the lips, nose, or eyelids.
Occasionally, the orbital rim might be resected, requiring bone grafts.
These are small-volume deficiencies with large surface area requirements.

Reconstruction Technique:

The radial forearm free flap is often the preferred choice.
Provides excellent external skin coverage and minimal bulk.
Allows for multiple skin islands that can be de-epithelialized for contour improvement, wrapping around bone grafts, or lining the nasal cavity.

Type II: Subtotal Maxillectomy Defects

These defects involve more significant resections while still preserving the orbital floor. They are classified further based on palatal involvement.

Type IIA Defects:

Involve resection of the lower five walls of the maxilla, including the palate.
Orbital floor remains intact.
Palatal defect is less than 50% of the transverse palate.
Moderate-volume deficiencies with large surface area requirements, usually needing one skin island.

Reconstruction Technique for Type IIA:

Can be reconstructed with a microvascular free flap or a skin graft and obturator (depending on patient/surgeon preference).
If a free flap is chosen to avoid the inconvenience of an obturator, the radial forearm fasciocutaneous free flap is favored.
Careful skin inset is vital, with the paddle equal to or smaller than the original defect to maintain a taut soft palate and recreate the buccal sulcus.

Type IIB Defects:

Involve resection of the lower five walls of the maxilla, including the palate.
Orbital floor remains intact.
Palatal defect is greater than 50% of the transverse palate, and/or involves the anterior arch of the maxilla.
Moderate-volume deficiencies with large surface area requirements, usually needing one skin island.
Require bone for structural support, as a prosthesis is inadequate for upper lip support.

Reconstruction Technique for Type IIB:

An osteocutaneous free flap is essential due to the need for bony support.
The radial forearm osteocutaneous “sandwich” flap is the flap of choice.
The bone segment reconstructs the maxillary alveolar arch and supports the upper lip.
Thin, pliable skin wraps around the bone to replace palatal and nasal lining.
Adequate bone harvest can also allow for osseointegrated dental implants or conventional dentures.

Type III: Total Maxillectomy Defects

These defects involve the resection of all six walls of the maxilla and are further subdivided based on orbital contents preservation.

Type IIIA Defects:

Involve resection of all six walls of the maxilla, including the palate and orbital floor.
Orbital contents are preserved.
Moderate-to-large-volume deficiencies with large surface area requirements, needing at least one skin island.

Reconstructive Goals for Type IIIA:

Support the globe.
Obliterate any communication between the orbit and nasopharynx.
Reconstruct the palatal surface.

Reconstruction Technique for Type IIIA:

A bone graft (e.g., split calvarium, iliac crest, split ribs) is needed for orbital floor reconstruction and maxillary prominence.
For mucosal and skin lining, the rectus abdominis myocutaneous flap is preferred.
This flap can be wrapped around the bone graft to separate orbital contents from the oral cavity and provide bulk to fill dead space, creating a watertight palatal closure.
In patients unsuitable for free tissue transfer, a temporalis flap can cover the bone graft and provide some volume, though it requires a simultaneous palatal obturator.

Type IIIB Defects:

Known as an extended maxillectomy, involving resection of the entire maxilla, including the orbital contents.
The dura and brain may be exposed; the palate is usually left intact.

Reconstructive Goals for Type IIIB:

Close the palate.
Restore nasal lining.
Reconstruct eyelids, cheek, and lip as needed.
Cover the exposed brain if the anterior cranial base is involved.

Reconstruction Technique for Type IIIB:

The rectus abdominis myocutaneous free flap with one or more skin islands is the flap of choice.
It is used to recreate the palate, lateral nasal wall, and address any cutaneous deficits.
The latissimus dorsi flap can also provide adequate soft tissue bulk and pedicle length, but is less versatile for multiple skin islands.

Type IV: Orbitomaxillectomy Defects

Characteristics:

Involve resection of the upper five walls of the maxilla.
Usually include resection of the orbital contents, leaving the dura and brain exposed.
The palate is typically left intact.
These are large-volume defects with large surface area requirements.

Reconstruction Technique for Type IV:

The rectus abdominis flap is the flap of choice.
One or more skin islands are used for external skin coverage and/or nasal lining.

Outcomes of Midface Reconstruction

Successful midface reconstruction aims for optimal functional and aesthetic results. A study of 100 patients demonstrated varied outcomes across different defect types:

Speech: 50% achieved normal speech, with 34.1% near normal. Only a small percentage faced unintelligible speech.
Diet: 52% of patients could eat an unrestricted diet, and 42% managed a soft diet.
Globe Position and Function: Among patients with orbital floor resection and preserved orbital contents, most maintained vision. Mild dystopia, diplopia, and enophthalmos occurred in a small number of cases. Ectropion was noted in 47.6% but generally mild to moderate.
Oral Competence: 91.7% of patients who underwent oral commissure reconstruction achieved good to excellent oral competence.
Aesthetic Results: 58.6% of patients had excellent aesthetic results, and 35.7% good. Achieving positive aesthetic outcomes was most challenging in cases involving skin, eyelid, or lip resections.

In conclusion, free-tissue transfer, particularly using radial forearm fasciocutaneous or osteocutaneous flaps for small to medium defects, and rectus abdominis free flaps for larger defects, consistently provides the best aesthetic and functional results for complex maxillectomy defects. This algorithmic approach, rooted in a precise anatomical classification, leads to highly effective and reliable midface reconstruction outcomes.

Frequently Asked Questions (FAQ) about Midface Reconstruction

What is the primary purpose of classifying midfacial defects?

The primary purpose of classifying midfacial defects is to provide a clear, standardized algorithm for reconstruction. This allows surgeons to assess the extent of maxillary bone resection and plan the most appropriate and effective surgical techniques, ensuring consistent and reliable functional and aesthetic results for patients.

What are the main types of free flaps used in midface reconstruction?

The main types of free flaps include the radial forearm free flap (fasciocutaneous or osteocutaneous “sandwich” versions) for smaller to medium-volume defects, and the rectus abdominis myocutaneous free flap for larger volume defects. The choice depends on the specific requirements for skin, soft tissue, and bone in the defect.

Can teeth be reconstructed after a maxillectomy?

Yes, in cases where adequate teeth or bone stock remain, conventional dentures or osseointegrated dental implants may be used to reconstruct teeth. This is particularly possible with osteocutaneous flaps that provide sufficient bone for implant support, such as the radial forearm osteocutaneous “sandwich” flap used for Type IIB defects.

What are some of the historical advancements in midface reconstruction?

Significant advancements include the introduction of biocompatible, rigid internal fixation hardware in the 1980s, which replaced older wire fixation methods. In the 1990s, improvements in osteocutaneous free tissue transfer allowed surgeons to transplant well-vascularized composite tissue. More recently, prosthodontists have enhanced the role of obturators as an adjunct or alternative for palatomaxillary defects.

What are the most common causes of midface defects requiring reconstruction?

The most common causes are related to oncologic surgery, primarily the removal of squamous cell carcinoma of the oral cavity or sinonasal mucosa, as well as minor salivary tumors and adenocarcinoma. Another significant cause is high-energy trauma, often requiring complex reconstruction alongside other craniofacial injuries.

Midface Reconstruction: Defects and Techniques