Background
The scapular/parascapular system of flaps is a unique system of flaps available for free tissue transfer based on the subscapular artery and its branches. In 1978, Saijo was the first to describe the scapular fasciocutaneous flap anatomy based on the circumflex scapular artery (CSA). [1] In the 1980s, dos Santos extensively studied the vascular supply of the free scapular flap in cadavers, contributing to the acceptance and use of free scapular flaps. [2, 3]
In a 1981 article, Teot et al identified the lateral border of the scapula bone as a potential source of vascularized bone based on periosteal branches of the circumflex scapular artery (CSA). [4] In 1986, Swartz et al popularized this particular flap in head and neck reconstruction. [5] In 1991, Coleman and Sultan identified the angular artery as the reliable blood supply to the scapular tip, allowing for 2 separate segments of bone to be harvested and improving the reliability of the scapular tip when harvested as a single segment. [6]
In 1984, Batchelor and Sully were the first to describe the incorporation of the latissimus dorsi muscle with the scapular/parascapular flap for reconstruction of a scalp defect. [7] Now, different combinations of the skin, muscle, and bone can be harvested to fit the reconstructive needs.
Presentation
Evaluation of the patient for consideration of a scapular/parascapular donor site includes an examination of the back and shoulder to rule out significant shoulder morbidity, scarring of the skin in the region, and any signs of vascular insufficiency. Previous axillary lymph node dissection calls into question the viability of the vascular supply to this flap and would preclude the use of this donor site.
Indications
The scapular/parascapular flap is the donor site of choice for complex 3-dimensional defects of the head and neck given the amount and variability of tissue types available for harvest. [8, 9] It is excellent for through-and-through oromandibular defects, which require tissue for intraoral and external skin lining, as well as bone. The scapular/parascapular flap is also ideal for defects that require a significant volume or bulk replacement. Up to 14 cm of bone can be harvested from the lateral border of the scapula bone. According to a 1993 report by Frodel et al and a 1994 report by Moscoso et al, the bone stock can be sufficient for the placement of osseointegrated implants and subsequent dental restoration, particularly in male patients. [10, 11] This donor site should also be considered when a fibula free flap is contraindicated because of inadequate collateral circulation, vascular insufficiency, or pitting edema to the lower extremity.
The scapular/parascapular system of flaps is also useful in reconstructing complex midface defects, which require skin or muscle for intraoral lining, external soft tissue coverage, or sinus cavity obliteration, as well as bone for alveolar reconstruction and globe support. [12, 13, 14, 15] Scalp defects can be reconstructed using fasciocutaneous scapular/parascapular flaps of the dorsal thoracic fascia with a split-thickness skin graft. Moreover, complex defects that involve the skull base, orbit, and midface can be restored with a single composite flap that provides bone for the maxilla or orbit, skin for an external cutaneous defect, and latissimus dorsi/ serratus anterior muscle for the skull base defect to provide support for the brain and separation of the dura from the nasal cavity and pharynx. [16, 17]
In addition, Fairbanks and Hallock (2002) reported on using the medial border of the scapula bone along with the lateral border for more complex oromandibular and maxillofacial reconstruction. [18] The lateral border and angle of the scapula was based on the angular artery and the medial border on the distal branches of the circumflex scapular artery (CSA).
Relevant Anatomy
The scapular/parascapular system of flaps is based on the subscapular artery and vein, branches of the third part of the axillary vessels. The advantage of this donor site is the various tissue types available for harvest, allowing tissue to be tailored to complex defects of the head and neck. Moreover, the vessels of the trunk are less commonly involved by atherosclerotic changes. A number of different flaps can be harvested on a single pedicle, and any combination of these flaps may be harvested, depending on the needs of the defect.
Flaps based on the subscapular arterial system include the following:
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Scapular/parascapular fasciocutaneous flap
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Scapular/parascapular osteocutaneous flap
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Latissimus dorsi muscle flap
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Latissimus dorsi musculocutaneous flap
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Serratus anterior muscle flap
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Serratus anterior musculocutaneous flap
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Dorsal thoracic fascia flap
The subscapular artery has a number of branches that are critical to the understanding of this system of flaps. The 2 major branches of the subscapular artery include the circumflex scapular artery (CSA) and the thoracodorsal artery (TDA). The circumflex scapular artery (CSA) runs through the muscular triangular space and branches into transverse and descending cutaneous branches, which form the basis of the scapular and parascapular fasciocutaneous flaps. [19, 20]
The circumflex scapular artery (CSA) also has periosteal branches, which supply the lateral aspect of the scapular bone except the tip of the scapula. The scapular tip can be supplied by either the circumflex scapular artery (CSA) or the angular branch of the TDA or serratus anterior branch. Two venae comitantes accompany the circumflex scapular artery (CSA) and drain into the thoracodorsal vein; however, the venous anatomy is variable. The TDA runs deep to the teres major and has a number of critical branches that are important in the understanding of this donor site. The angular branch that supplies the tip of the scapular bone is important and must be preserved in order to successfully transfer this portion of bone. [6] The branch to the serratus anterior also arises from the TDA. The distal portion of the TDA terminates into vertical and transverse branches, which supply the latissimus muscle and overlying skin.
The lateral aspect of the scapula bone is available for harvest based on the periosteal branches of the circumflex scapular artery (CSA). Approximately 10 cm of bone is available for harvest in females, and 14 cm of bone is available in males. [5] The tip of the scapular bone is supplied by the angular artery, which has a variable branching pattern. [6, 21] It usually arises as a branch of the TDA or as a branch of the main serratus collateral. [21] This allows the harvest of 2 separate segments of bone from the lateral aspect of the scapula.
Contraindications
Positioning patients who are obese for flap harvest may prove difficult and preclude the use of this donor site. Also, previous axillary lymph node dissection calls into question the viability of the vascular supply to this flap and would preclude the use of this donor site. Moreover, if simultaneous neck dissection is performed, further postoperative shoulder dysfunction needs to be considered.
The only possible limiting factor in the use of this versatile flap may be the length of harvestable bone. Reconstructing the entire mandible is not feasible; neither is angle-to-angle reconstruction. This may also be related to the number of osteotomies that can be made safely on the bone to contour to the native mandible. Also, some concerns have been raised over the potential implantability of these bones, especially in female patients.
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Composite defect that involves the mandible and oral tongue.
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Design of the scapula osteocutaneous free flap. An external Doppler was used to mark the horizontal and vertical segments of the vessel.
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The circumflex scapular and thoracodorsal vascular system.
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Scapular bone and skin harvested.
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Reconstruction of the composite defect with scapular osteocutaneous flap.
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Large through-and-through defect of the mandible, oral mucosa, and external skin.
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Insetting of the tissue.
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Defect reconstructed with the scapular free flap.
