The Temporoparietal Fascia Free Flap
The temporoparietal fascia (TPF) flap (TPFF) should be used in situations where vascularized, thin, pliable tissue is needed. Because of its high pliability, it can be used to cover irregular surfaces, to fill in concavities, and to wrap around gliding structures such as tendons. As with any axial pattern flap, it will bring in a new blood supply, which will aid with the preservation of exposed structures, such as bones and joint surfaces, and will deliver white blood cells and antibiotics to aid in the eradication of infection.
The ideal candidate has a defect of the hand/wrist requiring thin, pliable tissue.
Typically, defects are on the dorsum of the hand and involve exposed bone and/or joint, exposed tendon, or tendon defects requiring an interposition graft.
More proximal defects with exposed tendons or neurovascular structures may also be well served by this flap.
There are no specific age limitations to use of this flap.
It can be used acutely or electively for limb reconstruction.
Patient who cannot tolerate the length of a free flap procedure
Significant trauma to the lateral head
Deep laceration to temporal scalp
Zygomatic arch fracture
Cervical spine injury, with inability to remove the collar/position the head, or placement of halo screws through the flap or so close to the flap that they impair flap harvest
Temporal baldness (visible donor site scar)
History of temporal arteritis or other vasculitis affecting the scalp
Hemifacial/craniofacial microsomia (see “Relevant Anatomy”)
The superficial temporal artery can be palpated anterior to the root of the helix (the curled ridge on the outer edge of the ear).
The temporal scalp should be examined to confirm that there is no evidence of previous trauma that might have disrupted the flap pedicle or tissue planes.
The course of the temporal artery can be located with a Doppler probe.
If there is any question regarding the presence and quality of the superficial temporal artery, computed tomographic (CT) angiography demonstrates this very well ( Fig. 40.1 ).
The flap size can be up to 12 × 14 cm.
The layers of tissue in the temporal region from superficial to deep consist of:
Hair-bearing skin and subcutaneous tissue (includes auricularis muscles in the subcutaneous tissue)
Temporoparietal fascia with the accompanying superficial temporal artery and vein
A loose areolar plane
The temporoparietal fascia is continuous superiorly with the galea aponeurotica, posteriorly with the occipitalis, anterosuperiorly with the frontalis, and anteroinferiorly with the superficial muscular apo-neurotic system (SMAS) ( Fig. 40.2a ).
Due to the dense adherence of the skin to the underlying flap superiorly, begin the dissection at the pedicle to ensure identification of the appropriate plane for flap dissection.
Mark the projected course of the frontal branch of the facial nerve on the skin; this is helpful to avoid overly aggressive anterior dissection, which could expose the nerve to injury.
Controlling the middle temporal artery is easier to do after the flap has been elevated superiorly to allow better visualization of this branch.
Hirasé and Kojima stress the importance of not placing the side of the flap with the vessels exposed (the superficial surface in the native location) directly against tendons. We have not observed this to be critical to the success of the flap.
When elevating the skin and subcutaneous tissue off of the flap, as dissection proceeds superiorly, avoid excessive cautery, to decrease the risk of alopecia.
The temporalis fascia exists as a single layer over the temporalis muscle and continues superiorly as the periosteum of the tempoparietal bone ( Fig. 40.2b ).
The temporoparietal fascia flap is supplied by the superficial temporal artery (pedicle length 2.5–5.0 cm; diameter 1.5–2.7 mm), a branch of the external carotid artery. It passes superior to the digastric muscle and then between the superficial and deep lobes of the parotid gland deep to the facial nerve.
The artery then emerges from the parotid lateral to the temporomandibular joint, where it gives off the middle temporal artery and the transverse facial artery before entering the temporoparietal fascia at the level of the zygomatic arch.
Superior to the zygomatic arch, the superficial temporal artery runs along the surface of the temporoparietal fascia, dividing into multiple anterior and posterior branches, with variable middle branches.
The middle temporal artery enters the fascia of temporalis muscle slightly superior to the zygomatic arch and is the dominant pedicle for the fascia of temporalis muscle flap ( Fig. 40.2b ).
Inclusion of the middle temporal artery will enable harvest of the superficial fascia of the temporalis muscle, along with the TPF based on the superficial temporal artery pedicle proximally ( Fig. 40.2c ).
If proximal dissection of the superficial temporal artery is performed, the transverse facial artery should be identified prior to ligation.
The superficial temporal vein (pedicle length 2.5–5.0 cm; diameter 2.1–3.3 mm) provides dominant venous out-flow and usually exists anterior to the superficial temporal artery and its branches, although it has been reported up to 3 cm away from the superficial temporal artery.
Additional minor pedicles include the occipital artery (pedicle length 2.7–9.7 cm; diameter 0.6–2.0 mm) and the posterior auricular artery (pedicle length 5.1–7.7 cm; diameter 0.7–1.2 mm). These are relevant only for higher-risk cases where superficial temporal artery hypoplasia or anomalies are likely, such as hemifacial microsomias, Treacher Collins syndrome, and Romberg disease (hemifacial atrophy).
The occipital vein (pedicle length 6 cm; diameter 1.2–2.0 mm) or posterior auricular vein (diameter 2.4 mm) may provide significant outflow in a minority of cases. These veins are frequently friable and of poor quality for anastomosis.
The flap has sensory innervation from the auriculotemporal nerve of the third trigeminal division. The nerve passes posterior to the mandibular condyle and lies deep to the superficial temporal artery at the level of the tragus, but superficial to the superficial temporal artery at the level of the zygomatic arch. It then proceeds along the superficial temporal fascia posterior to the superficial temporal artery and vein.
The zygomaticotemporal nerve supplies sensory innervation to the anterior temporal region; it is not harvested during flap elevation because of its close proximity to the temporal branch of the facial nerve.
The temporal branch of the facial nerve passes over the zygomatic arch 2 cm anterior to the anterior concavity of the external auditory canal. Superior to the zygomatic arch, it runs on the surface of the fascia of the temporalis but parallel to the anterior branch of the superficial temporal artery.
The temporal branch of the facial nerve runs along the anterior extent of the flap dissection. Its topographical course runs from a point 0.5 cm below the tragus to a point 1.5 cm above the lateral eyebrow.
Dissection should not continue anterior to this line because of the risk of facial nerve injury. Injury to the nerve at this level will lead to brow asymmetry and ptosis due to paralysis of the orbicularis oculi, procerus, corrugators, and frontalis.