Maxillary Reconstruction



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Maxillary Reconstruction


  • Maxillectomy defects become more complex when critical structures such as the orbit, globe, and cranial base are resected


Anatomy

  • The maxilla can be described as a geometric structure with six walls (hexahedrium)

  • The roof of the maxilla supports the ocular globe. The medial wall is the lateral wall of the nasal cavity and is part of the lacrimal system

  • The floor of the maxilla forms the anterior portion of the hard palate and the alveolar ridge

  • Several walls of the maxilla contribute to formation of the paranasal sinuses, and the maxillary antrum is contained within the central portion of the maxilla.

  • two horizontal and three vertical buttresses of the maxilla are responsible for midfacial projection and vertical facial height.

  • most muscles involved with facial expression and mastication are inserted on the maxilla. These muscles, together with the overlying skin and/or intraoral mucosa, constitute the lower eyelid, cheek, upper lip, and oral commissure.




  • maxillary bone is usually included when resecting tumors that arise from the paranasal sinuses, palate, nasal cavity, orbital contents, overlying skin, or intraoral mucosa.


Classification (Cordiero PRS June 2000)

    1. Type I defects (limited maxillectomy)

      • resection of one or two walls of the maxilla, excluding the palate

    2. Type II defects (subtotal maxillectomy)

      • resection of the maxillary arch, palate, anterior and lateral walls (lower five walls), with preservation of the orbital floor

    3. Type III defects (total maxillectomy)

      • resection of all six walls of the maxilla

      • type IIIa, - the orbital contents are preserved

      • type IIIb,- the orbital contents are exenterated

    4. type IV defects (orbitomaxillectomy)

      • resection of the orbital contents and the upper five walls of the maxilla, with preservation of the palate


Reconstruction

  • Free-tissue transfer provides the most effective and reliable form of immediate reconstruction for complex maxillectomy defects.

  • The rectus abdominis and radial forearm flaps in combination with immediate bone grafting or as osteocutaneous flaps reliably provide the best aesthetic and functional results.

  • Bone replacement is essential in the floor of the orbit to maintain position of the ocular globe- otherwise, the orbital contents sink into the cheek, creating a dystopia, diplopia, and essentially nonfunctional eye.

  • It is also useful in the maxillary arch to provide anterior projection of the midface and bone stock for osseointegrated implants

  • Bone grafts can be effectively used in conjunction with soft-tissue flaps (free or pedicled) for reconstruction of the orbital floor, because this area requires minimal supportive strength.

  • Vascularized bone is indicated in the maxillary arch if osseointegration is required.

  • Free flaps generally are indicated when skin islands are necessary for intraoral cheek, palatal, nasal lining, or external resurfacing.

  • The space between the restored anterior, superior, and inferior walls of the maxilla can usually be filled with soft tissue (muscle/fat)

  • nasal lining may or may not be necessarily restored.

  • The temporalis flap covers bone effectively in these types of reconstruction but does not close the palate; this requires subsequent use of an obturator. It is therefore indicated primarily in older patients who are not candidates for free-tissue transfer

  • A superficial tunnel in the face-lift plane allows transfer of vessels; or, if the maxillary tubercle is resected, access can be gained by a parapharyngeal approach medial to the mandible




(Above) Type I (limited maxillectomy) defect. Note resection of anterior and medial walls of maxilla (left). Resected specimen demonstrates skin/soft-tissue resection in combination with bony resection (center, left). This creates a large surface-area/low volume defect. The radial forearm fasciocutaneous flap (donor site depicted in inset) provides multiple large skin surface areas with minimal volume (center, right). (Right) Radial forearm fasciocutaneous flap is shown in place, demonstrating skin islands to resurface anterior cheek and medial nasal lining. (Below) Type II (subtotal maxillectomy) defect. Note resection of lower five walls of maxilla, including the palate, but sparing the orbital floor (roof of maxilla) (left). Resected specimen demonstrates palatal/nasal floor lining and bony resection. This creates a large surface-area/medium volume defect (center, left). The radial forearm osteocutaneous sandwich flap (donor site depicted in inset) provides large skin surface area with vascularized bone and moderate volume (center, right). (Right) Radial forearm osteocutaneous flap is shown in place, demonstrating strut of vascularized bone to reconstruct the anterior maxillary arch deficit sandwiched between two skin islands that replace palatal and nasal lining.


Above) Type IIIa defect. Note resection of all six walls of the maxilla, including the floor of orbit and hard palate. The orbital contents have been preserved (left). Resected specimen demonstrates the orbital floor, vertical maxillary buttresses, and palatal resection (center, left). This creates a medium surface-area/medium volume defect. Cranial or rib bone graft is used to reconstruct floor of orbit and is covered with single-skin-island rectus abdominis myocutaneous flap (center, right). The rectus abdominis myocutaneous flap (donor site depicted in inset) provides medium surface area with medium volume. The bone graft is rigidly fixed to reconstruct the floor of orbit. The rectus abdominis myocutaneous flap is inset with the skin island used to close the roof of the palate, soft tissue to fill in midfacial defect, and muscle to cover bone graft. Note extended length of deep inferior epigastric vessels to neck (right). (Below) Patients who are not free-flap candidates may be reconstructed with split calvarial bone grafts, covered with the temporalis muscle, transposed anteriorly. The zygomatic arch should be osteotomized and removed temporarily to increase excursion of the temporalis muscle.

(Above) Type IIIb defect. Note resection of all six walls of the maxilla, including the floor of the orbit as well as orbital contents (left). Resected specimen demonstrates resection of external eyelid, cheek skin, and orbital contents, in combination with entire maxilla and palate (center, left). This creates a large surface area/large volume defect. A three-skin-island rectus abdominis myocutaneous flap design is shown in the inset. This flap provides multiple large surface areas with large volume of soft tissue and muscle to fill in the defect (center, right). Rectus abdominis myocutaneous flap (inset) demonstrates skin islands to resurface the external skin and palatal defect with muscle and subcutaneous fat used to fill in soft-tissue deficit. If technically feasible, a third skin island can be used to reconstruct the lateral wall of nose (right). (Below) Type IV (orbitomaxillectomy) defect. Note resection of upper five walls of maxilla, including the orbital contents but sparing the palate (left). Resected specimen demonstrates resection of orbital contents, eyelid, and cheek skin, in continuity with bone (center, left). This creates a large surface area/large volume defect. Note design of single-skin-island rectus abdominis myocutaneous flap (depicted in inset). This flap provides large surface area with large volume to reconstruct the defect (center, right). Rectus abdominis myocutaneous flap in place, demonstrating skin island to resurface the external skin defect with muscle and subcutaneous fat used to fill in the soft-tissue deficit (right).




Combined nasal reconstruction

  • Because the nose is not essential from the functional standpoint, reconstructionshould be delayed.

  • When the maxilla is resected in combination with the nose, the resulting defect is massive.

  • Local tissues (septum, nasal lining flaps, nasolabial flaps) that are usually used for reconstruction of the nose are often unavailable.

  • An additional free flap is often necessary to provide adequate tissues for lining and support and often yields marginal aesthetic results.

  • The quality of prostheses is so much better than with reconstructiont using the paucity of local tissues (often irradiated). Most would advocate a prosthesis for these patients. A delayed reconstruction of the nose can then be carefully planned if indicated.


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