Scalp Reconstruction

The scalp delineates the superior margin of the body, a position that is commonly exposed to considerable insults from the surrounding environment. Its exposed location, which is generally devoid of clothing coverage, makes the scalp susceptible to burns and other trauma that can produce extensive scarring and disfigurement. Additionally, the scalp is subject to a staggering variety of benign and malignant neoplasms, often as the result of years of sun exposure. Today, many scalp defects encountered prior to reconstruction are the product of ablative surgery, often Mohs micrographic surgery.[1]

Tissues that are traumatized, irradiated, or infected surround many of these defects. Patients are frequently elderly with multiple medical problems that may limit their ability to tolerate certain procedures. Thus, the repair of a scalp defect can involve treatments ranging from the simplicity of a few sutures to a multi-month, multi-procedure reconstruction.

The decision-making process behind a successful outcome requires a solid knowledge of anatomy, a clear evaluation of the defect, the recognition of relevant patient attributes, and the knowledge of a variety of reconstruction options. Preoperative planning is imperative. Preoperative plans must be specifically tailored to the individual problem because no single solution is available for reconstructing the scalp.

An image depicting scalp anatomy can be seen below.

The surgeon should clearly understand the elements of scalp anatomy before attempting reconstructive procedures. The scalp is defined as the anatomic area overlying the skull between the superior orbital rims anteriorly and the superior nuchal line posteriorly. This anatomic space is divided into hair-bearing and non–hair-bearing (ie, forehead) segments. The forehead further is divided into 5 subunits: the central, the left and right temporal, and the left and right brow subunits.

The soft tissue within this region is commonly divided into 5 layers: skin, subcutaneous tissue, aponeurosis (galea), loose areolar tissue, and pericranium. These layers easily are remembered using the mnemonic "SCALP" (see the image below). An external layer of thick skin is fixed to the underlying subcutaneous layer of fat. This subcutaneous layer is richly vascularized and provides a fibrous bridge to keep the skin tightly fixed to the galea aponeurosis (ie, epicranium) beneath. The galea aponeurosis is essentially the membranous tendon extension connecting the frontalis and occipitalis muscles, and it is the superficial musculoaponeurotic system (SMAS) layer of the scalp.

The galea aponeurosis becomes an important layer clinically, especially with coronal defects through the galea, because the antagonistic forces of the frontalis and occipitalis muscles widely separate the wound edges. However, if the aponeurosis remains intact, skin retraction is much more limited. When reconstructing scalp defects, limiting separation of the galea from the overlying skin is important to avoid devascularizing the skin. Laterally, the galea becomes contiguous with the temporoparietal fascia (ie, superficial temporal fascia). The temporoparietal fascia is a richly vascularized layer that envelopes several key structures, notably the frontal branches of the facial nerve, the auriculotemporal nerve, and the superficial temporal artery and vein.

Below the galea is a layer of loose connective or areolar tissue. This layer provides for relatively free movement between the aponeurosis and the deepest layer, the pericranium. It also creates a point of separation during traumatic scalping injuries. The pericranium is composed of dense connective tissue tightly affixed to calvarial bone by Sharpey fibers. In general, these fibers are easy to strip off the underlying bone, although they may be strongly adherent along the cranial sutures. As the pericranium approaches the superficial temporal line laterally, it divides to form 2 layers, the temporalis muscle fascia (deep temporal fascia) and the pericranium of the temporal bone. These 2 layers together invest the body of the temporalis muscle. Inferior to the temporalis muscle, the temporalis fascia splits to invest the superficial temporal fat pad, and then it inserts into the zygomatic arch.

Although a rich network of anastomotic connections is present, the blood supply to the scalp is primarily derived from 5 pairs of arteries (see the image below). Arising from the ophthalmic artery and thus from the internal carotid artery, the supratrochlear and supraorbital arteries supply the forehead and anterior scalp. The external carotid gives rise to 3 pairs of arteries, the superficial temporal, postauricular, and occipital. These vessels are found in the subcutaneous layer immediately superficial to the galea with only minimal contributions to the deep pericranial layer. The pericranium is nourished via the middle meningeal and intracranial circulation to the calvarial bone. As a result, disruption of blood supply to the scalp does not result in calvarial bone necrosis. Venous drainage parallels the arterial system and eventually drains into the internal and external jugular veins.

Interestingly, sensory innervation of the anterior scalp is derived from all 3 branches of the trigeminal nerve via the supraorbital and supratrochlear nerves (V1), the zygomaticotemporal nerve (V2), and the auriculotemporal nerve (V3). The posterior scalp receives sensory innervation from cervical sensory branches through the greater (C2) and lesser (C2, C3) occipital nerves.

Motor innervation to the forehead derives from the facial nerve. The frontal branch of the facial nerve exits the parotid gland running in an oblique line lateral to the lateral orbital rim to supply the frontalis, corrugator supercilii, and procerus muscles. A posterior auricular branch of the facial nerve provides function to the occipitalis muscle. Motor branches, which are the deep temporal branches of the mandibular nerve (V3), innervate the temporalis muscle.

Lymphatic drainage of the scalp runs primarily into the ring of lymph nodes located along the junction of the head with the neck. These are the submental, submandibular, parotid/preauricular, retroauricular/mastoid, and suboccipital nodes. These groups of lymph nodes eventually drain into the deep cervical chains of lymph nodes.

No specific contraindications exist for scalp reconstruction. However, if the patient's underlying medical condition(s) prevent general anesthesia, this may limit the scope of the planned reconstruction. In rare patients, significant medical risk factors may prevent even the most limited reconstructions, including procedures that can be performed with the patient under local anesthesia. In these patients, strong consideration should be given to allowing the wound to heal by secondary intent. The surgeon's role in these situations is not so much to reconstruct the scalp but to coach it through the healing process with good wound care and conservative debridement of nonvital tissues when necessary.

The surgeon must consider several factors when selecting the appropriate method of reconstruction.[2] Identification of the anatomic elements involved in the defect is of primary importance. Repairing a defect that crosses anatomic and aesthetic subunits of the scalp requires careful reconstruction so that structures such as the eyebrows or hairline are not distorted once the wounds have healed. Larger defects are more difficult to close than smaller defects and may require elevation of multiple flaps or use of complex techniques.

Next, the surgeon should assess depth of injury. The manner of reconstruction varies dramatically depending on the involvement of galea, pericranium, and/or calvarial bone. If bone is exposed, immediate skin grafting may not be an option. If bone loss is significant, bone grafting or reconstruction with prosthetic material may become necessary. If the defect extends into the dura or brain, reconstruction may involve a combined procedure in association with neurosurgical colleagues.

Certain local flaps may be impossible to use if key arterial units have been disrupted. Similarly, resection or loss of temporalis muscle, galea, or pericranium can prohibit the use of certain local flaps. Early recognition of division or loss of the temporalis muscle and its blood supply is important because temporal wasting, which alters the final outcome, may develop over time.

Finally, assess the tissues around the defect. Shotgun wounds or other blast-effect injuries often exhibit considerable delays before viable tissues can be differentiated from nonviable tissues. Other traumatic injuries may leave the surrounding tissues contaminated with dirt, gravel, or glass. Oncologic resections need to be reconstructed in a manner that easily allows future evaluation for recurrent tumor of the wound bed. A history of irradiation or severe solar damage leaves tissues with decreased elasticity and poor wound healing characteristics. Earlier operative procedures or trauma creates scarring that can drastically affect mobilization of local flaps.

Medical conditions (eg, diabetes mellitus, collagen vascular diseases, chronic steroid use, immunosuppression) alter rates of wound healing and increase the likelihood of wound infections. Smoldering calvarial osteomyelitis can convert healthy local flaps into flap failures if undetected. Complications are more likely when a history of radiation, smoking, chemotherapy, cerebrospinal fluid leak, or an anterior location of the ablative defect exists. Anterior defects may be more prone to complications since the scalp is thinner here and the frontal sinus may act as a source of contamination.

However, a retrospective study by Yu et al indicated that in free flap scalp reconstruction, perioperative radiotherapy is not a significant risk factor for major complications. Nor were flap type, previous scalp surgery, and recipient vessel selection determined to be significant risk factors. The study did find that cardiovascular disease is a risk factor for major complications; these occurred in 36.7% of free flap patients with cardiovascular disease but in only 12.1% of those without a cardiovascular disorder.[3]

A wide variety of techniques has been used to close scalp defects.

Primary closure

For small defects, primary closure may be the best option. Typically, defects less than 3 cm in diameter can be closed primarily, but this varies depending on location. If primary closure is selected, any defect in the galea should be closed first with buried resorbable sutures, and skin edges should be reapproximated using suture or staples.

Because the scalp tends to be limited in its ability to stretch for closure of defects beyond 3 cm, several techniques can be helpful. Simple undermining beneath the galea may release enough tension to help close some small defects, but, generally, this measure does not significantly improve closure of larger defects. Stretching neighboring scalp has been demonstrated to create some extra scalp length. This technique relies on the "creep and stress" properties of skin. After a period of constant tension (ie, ≥5 min) with skin hooks, the biomechanical properties of the scalp allow for some degree of permanent stretching, although most of the immediate gains are probably lost.

Adequate advancement of tissue can occasionally be achieved using releasing incisions or galeatomies. The surgeon should take care to place these incisions parallel to the surrounding blood supply. Recommendations on how to space these incisions vary, with some authors suggesting 1- to 2-cm intervals and others recommending 0.5- to 1-cm intervals. In either case, the principle is the same: release of the tough fibrous structure of the galea should allow for some limited stretching of the overlying skin.

All these techniques for primary closure are of limited help when closing any defect of substantial size. Thus, they commonly lead to poor outcome by ultimately creating wounds with excessive tension or undermined tenuous blood supply.[4]

Vacuum-assisted closure

A vacuum-assisted closure device works by applying uniform subatmospheric pressure to the wound, allowing it to develop a better blood supply, decrease bacterial counts, and develop robust granulation tissue. This technique has been used successfully in patients with moderate-to-large defects involving the scalp and forehead.[5] Success was also noted when bare bone devoid of periosteum was involved. The device is used for several weeks, and results in granulation tissue formation, wound contracture, and reepithelialization.

Replantation

Total scalp avulsions are devastating injuries that are often caused by long hair getting caught in machinery. The best treatment for scalp avulsion is immediate replantation of the avulsed tissue using microsurgical techniques. First, the scalp hair should be shaved and rinsed thoroughly in running tap water. Next, scalp vessels are identified in both temporal areas. The galea is incised for 2-3 cm to mobilize the vessels. If identified, the supraorbital, supratrochlear, and postauricular vessels are tagged. The entire posterior margin of the scalp segment then undergoes bipolar cautery.[6]

Next, the patient is anesthetized, the scalp dressing is removed, and bleeding vessels are controlled with micro clamps. The scalp is anchored to the head with quilting sutures. All available vessels in the frontal and temporal areas are re-anastomosed. At least one artery and two veins are repaired. Vein grafts are usually not necessary. Nerve repair is not performed, since spontaneous re-innervation occurs.

Skin grafting

Placing split-thickness skin grafts can provide a quick and effective means of defect closure. The grafts are technically easy to harvest and involve only limited donor site morbidity. Skin grafting may suffice for closure in many situations, most notably in elderly patients whose overall medical condition prohibits more extensive procedures or in patients who require close observation of the wound bed for recurrence of tumor (see the image below). Tumor surveillance is a key concern following resection of certain tumors (eg, melanoma, recurrent sclerosing basal cell carcinoma, dermatofibrosarcoma protuberans, malignant fibrous histiocytoma). Grafts can also be used as coverage for either local or free flap transfer of muscle to close extensive scalp and/or bone defects.

Skin grafts require an adequately vascularized wound bed and are not successful if applied directly to exposed bone. Intact pericranium is typically sufficient to support a skin graft. Fully débride any necrotic tissue prior to application. Recipient beds should also be hemostatic to prevent development of hematoma beneath the graft, which can compromise success. Grafts applied to the scalp are not commonly meshed in an attempt to produce a more cosmetically appealing result with greater resistance to shearing forces. Meshing is an excellent option, however, if one anticipates removing the skin graft later (as in the case of serial excision or tissue expansion). Skin graft take is also possible over bone after burring of the outer cortex.

Skin grafts inevitably produce a final result with poor cosmetic match for skin color, thickness, and texture. Poor cosmesis is even more evident in hair-bearing portions of the scalp. For many, use of a wig or a hairpiece is a totally acceptable alternative. Closure of defects with local flaps almost always results in a better overall cosmetic result than a primary split-thickness skin graft.

Local flaps

The trend for treating defects of the forehead and scalp is one of conservatism. Appropriate wound care usually results in granulation tissue formation and reduction of the defect size over several weeks. This is especially true of forehead defects. Local flaps are probably best indicated for secondary reconstruction after excision of scars or primary skin grafts.

Local flaps may consist of skin, subcutaneous tissue, and galea, although occasionally small superficial defects may be adequately reconstructed using a flap elevated in the subcutaneous plane. Any local flap is best raised over a named arterial system.

• Rotational flaps: Rotational flaps may be unilateral or bilateral, and they are extremely useful for closing defects of the hair-bearing scalp (see the image below). Bilateral flaps allow wound tension to be spread over a wider surface area than unilateral flaps. Surgeons using rotational flaps should plan incisions that are 4-6 times the diameter of the defect. Rotational flaps can also be used on the forehead, where they produce a respectable appearance but usually denervate the adjacent skin. While the flap is raised, take care that the incisions are not carried across major vessels, especially the occipital vessels when raising posterior flaps in the hair-bearing scalp.

  Rotation flaps. A: Large basal cell carcinoma of the forehead. B: The resulting Mohs defect. C: Closure with 2 superiorly based rotation flaps. D: Appearance at 6 months.

• A-to-T flap: Using the A-to-T flap is an effective method for closing defects along the temporal and central forehead at the hairline (see the image below). This flap is essentially a combined rotation and advancement flap that requires incisions along either side of the defect. The procedure produces a T-shaped scar that is easily camouflaged at the hairline.

  An example of an A-to-T flap closure.

   

• Advancement flaps: Defects located within the central forehead can be closed using either unilateral or bilateral advancement flaps (see the image below).[7]  These flaps create parallel scars that are readily placed into the natural skin creases of the forehead. Small cones or Burow triangles need to be excised from the base of each advancement flap; however, the cones can often be placed into a brow or hairline.

  Advancement flaps. A: Mohs defect over the scalp vertex from a squamous cell carcinoma. B: Closure with bipedicled advancement flaps based on the right superficial temporal and left postauricular artery. C: Defect resulting from paramedian forehead flap. D: Closure with bilateral horizontal advancement flaps. E: Result at 6 months.

• Transposition flaps: Transposition flaps are commonly used to close lesions of the forehead, temporal, or glabellar regions. For small defects, a single transposition flap with primary closure of the donor site is often adequate. However, when using larger flaps, primarily closure of the donor site may become impossible. In this situation, the closure is usually better planned as either a bilobed transposition flap (see the image below) or a multilobed rhomboid style flap. Multiple flaps have been purported to spread the tension of the incision. However, rhomboid flaps, especially multiple rhomboid flaps, tend to create a complicated scar pattern that can be difficult to hide in skin tension lines.

  Transposition flaps. A: Large defect of the left anterior scalp. B: Design of transposition flap based on the superficial temporal artery. C: The flap is in place. The donor site will be skin grafted, and excess flap will be replaced in its original position in 3-4 weeks. D: Mohs defect of the anterior scalp. E: Inset of bilobed flap. F: Final result.

• Island flaps: Defects within the suprabrow pose a difficult reconstructive problem. Any repair undertaken must not alter the alignment of the eyebrows, or notable asymmetry results. Simple island flaps may be sufficient to replace suprabrow tissue with similar tissue from the superior forehead while allowing the suprabrow to close without distorting either the eyebrow or eyelid. The surgeon must take care to create a generous tunnel for a tension-free pedicle. Island flaps have also been used to reconstruct defects along the hairline by rotating in hair-bearing scalp from the vertex.

• Hatchet flaps: Hatchet flaps, or V-Y flaps, are another option for reconstruction of the suprabrow and forehead.[8] For these flaps, bilateral triangles are raised on subcutaneous pedicles and skin pedicles and are rotated medially into the wound. Closure then proceeds in a V-Y fashion. Multiple incisions and the inherent risk of ischemia from a tenuous blood supply often complicate these flaps.

Serial excision

Serial excision involves the staged removal of non–hair-bearing tissue over a period of several months. By only removing a portion of the tissue at a time, one ensures that the scar will not widen inordinately and that the wound edges will not separate or necrose. Serial excision is most appropriate for areas of alopecia less than 50 cm2 in the vertex or occiput.[9]

Scalp extender surgery

Scalp extension is a technique in which a stretchable device consisting of a Dacron-reinforced elastic silicone sheet with multiple hooks is implanted.[9] To be effective, the patient's scalp scar should have moderate-to-good flexibility and be located on the vertex.

Hair transplants

These are effective in limited areas with adequate blood supply and subcutaneous tissue. In the case of exposed periosteum, the site may be grafted first with a dermal regeneration template followed by a split-thickness skin graft several weeks later.[10] The site may then be implanted with micrografts to recreate hair density.[11]

Tissue expansion

Skin grafts are commonly used as a temporizing measure, often to allow time for expansion of neighboring tissue.[12] Tissue expansion usually provides ample tissue with preservation of scalp sensation, color, thickness, and hair; however, it ultimately requires a minimum of 2 operative procedures. Patients should understand beforehand that this requires a commitment of at least 1-2 months (see the image below).[13]

Although expansion does not alter the growth of hair follicles, it also does not stimulate new follicle growth. Thus, the density of hair follicles falls during expansion. This is typically not of major concern because reduction in hair density is not readily noticeable until follicle density has decreased by 50% or more. Thinning, thus, does not become a concern until the skin has expanded by at least 2-fold.

The surgeon should place expanders in a subgaleal plane through access incisions situated as far from the area of tissue to be expanded as feasible. When used with skin grafts, the expander should be positioned away from the interface between normal and grafted tissue to avoid wound dehiscence. Expanders should not be placed beneath scarred or previously radiated tissue. Baker suggests selecting an expander or combination of expanders with a basal surface area 2.5 times the surface area of the defect to be reconstructed.[14] He feels that rectangular or crescent expanders work better than round expanders and that use of multiple expanders surrounding the defect allows for more rapid expansion while minimizing visible deformity than use of single large-volume tissue expanders.

Filling of the expander is conducted on a weekly basis, usually in volumes of 35-50 mL/wk. Typically, the bladder is filled to the point at which the patient reports a sensation of tightness or mild discomfort. Signs of blanching or discoloration of the overlying skin should be taken as warnings that too much normal saline has been injected. Within 8-10 weeks, the scalp usually expands sufficiently to allow for closure.

Once the necessary expanded scalp is available, the second stage of reconstruction may begin. First, the tissue expander is removed from its fibrous capsule. Baker states, "No attempts should be made to remove the capsule," and Azzolini advocates leaving the capsule in place to avoid damaging hair follicles.[14, 15] The scalp is then mobilized from the pericranium and rotated as necessary into position, where it is closed over a suction drain. If a defect remains, reexpansion may be an option, but it should be delayed a minimum of 3 months to allow for complete wound healing.

Considerable concern has been expressed in the literature regarding the effects of prolonged scalp expansion on calvarial bone, especially in the pediatric population, with multiple authors reporting cases of bony erosion secondary to tissue expanders. In a study using neonatal pigs, Moelleken found that tissue expanders caused erosion of the outer table of bone but no changes in the inner table. Additionally, researchers found that after the implant was removed, reparative bone remodeling began within 5 days, and near-complete healing of cranial defects occurred within 2 months. Calobrace described similar clinical findings in a 5-year-old boy who developed profound outer table deformity followed by near complete remodeling with minimal visual deformity 6 months after expander removal.[16]

Other disadvantages of tissue expansion include added time for reconstruction, visual deformity of the expanded site, risk of infection or extrusion of expanders, hematomas, and necrosis of the overlying skin from overzealous expansion.

Coverage of exposed bone

Before skin grafts are placed, exposed, bare bone requires coverage with some type of vascularized soft tissue. Rotation of temporoparietal or galeal flaps provides an excellent option for coverage. These flaps are usually based off of 1 or both of the superficial temporal arteries. Potentially, they can be based off of any of the 5 pairs of scalp arteries. These flaps require elevation of the overlying skin in a subfollicular plane, which can result in alopecia, scalp anesthesia, and injury to the frontal branch of the facial nerve. In general, these flaps provide good conformity to the underlying bone, appropriate thickness, excellent blood supply (with good subsequent skin graft take), and a wide arc of rotation with minimal donor site scar or deformity.

Pericranial flaps are commonly used for frontal bone coverage when based off of the supraorbital and supratrochlear arteries. These flaps are raised off the calvarial bone and then dissected free from the scalp in the loose areolar plane. They are quite mobile and can be used in a turnover pattern, in which the flap is rotated in a 180° arc around its pedicle, also referred to as the subgaleal-periosteal turnover flap. Additionally, osteoplastic flaps incorporating pericranium and calvarial bone can be raised, typically off of the temporal pedicle using parietal bone. These flaps are generally harvested with intact overlying galea to preserve blood supply. A split-thickness skin graft completes closure. The advantage of these flaps is that they do not require dissection in the subcutaneous plane.

Skin grafts can be placed onto a bed of calvarial bone after portions of at least part of the outer table are removed. Traditionally, this has required drilling multiple burr holes into the outer table of bone and then waiting for granulation tissue to grow out of the burr holes. After a period of several weeks, the wound bed generally develops enough vascular ingrowth to support skin grafts.

The Punjab region of India contains a large population of Sikh men whose religion prohibits them from cutting their hair. Not surprisingly, a high number of scalp injuries occur in the area, usually as a result of hair becoming entangled in farming machinery. Working in India, Feierabend and Bindra developed a single-stage technique for laying skin grafts onto exposed bone.[17] Rather than drilling the outer table, it is chiseled down to the point at which it begins to bleed, removing only the avascular portion of bone. This leaves most of the outer table intact. Once active bleeding has been controlled, split-thickness skin grafts are placed into position. The authors believe that immediate application prevents drying and thrombosis of the exposed vessels. Use of their technique has dramatically reduced lengths of hospitalization and number of operative procedures.

Other authors have evaluated the ability of exposed calvarial bone to heal by secondary intent. This may be a viable option for patients with aggressive or recurrent tumors requiring close local observation. In a retrospective review of 91 patients with exposed scalp or facial bones, Snow et al found a secondary intention wound-healing rate of 95%, with no cases of osteomyelitis.[18] They estimate that bone wounds granulate at a rate of 2 weeks for each centimeter of exposed bone diameter, while soft tissue defects epithelialize at a rate of approximately 3 weeks for each centimeter of wound diameter.

In situations involving frank bone loss, several techniques are available. Alloplastic materials (eg, acrylic, methylmethacrylate, titanium mesh) have been used with success. Infection and extrusion rates are less favorable than with autogenous reconstruction. Autogenous reconstruction typically uses either free or vascularized bone harvested from rib, calvaria, or ileum. Calvarial grafts tend to resorb less mass when compared to rib or ilium. Another intermediate option is hydroxyapatite, which can be applied directly or in combination with titanium mesh.

Closure of large scalp defects

Before the advent of free-tissue transfers, closure of scalp defects covering more than 15-20% of the scalp was essentially impossible with a single procedure. Even smaller wounds can be difficult to close when irradiated, infected, or traumatized tissue beds or cerebrospinal fluid leaks exist. Free flap techniques have allowed for reliable wound closure in such situations while providing a variety of reconstructive options.

Initially, free omentum was used with a split-thickness skin graft for coverage. This method has been mostly abandoned because of its reliance on an intra-abdominal procedure. However, since then, a variety of free flaps have been used to cover the scalp, including omentum, iliac crest, parascapular, gracilis, groin, and inferior epigastric flaps, as well as free-tissue transfer of existing scalp and even scalp from an identical twin. However, a few flaps deserve discussion in greater detail because they are commonly used.

• Radial forearm flap: The radial forearm flap provides an excellent choice for coverage of smaller defects in which osseous reconstruction is not needed. This flap is easily raised with a consistently long reliable pedicle with large-caliber vessels. The match between scalp and forearm tissue is quite good, and the skin provides good durability. The forearm flap is especially good for forehead unit replacement. The flap is limited to only 250 cm2 of total coverage, which can be inadequate for large defects. This limitation has been overcome in the past through the use of preimplanted tissue expanders. Additional disadvantages of the radial forearm free flap are its requirement for skin grafting the donor site and the small but real potential for tendon exposure.

• Anterolateral thigh flap: The anterolateral thigh flap is also an excellent choice for coverage of defects in which osseous reconstruction is not needed. This flap is also easily raised with a consistently long reliable pedicle with large-caliber vessels. The flap is suitable for large defects, ranging in length up to 27 cm and 18 cm in width. Donor site morbidity is minimal, and many donor sites may be closed primarily.

• Latissimus dorsi free flap: The free latissimus flap is probably ideal since it has a long dominant pedicle based on the thoracodorsal vessels and is large and pliable.[19] Composite flaps have been shown to function better than muscle-only flaps.

• Serratus anterior flap: Serratus anterior flaps can be used alone or in conjunction with latissimus dorsi flaps (see the image below). This combination allows for coverage of enormous defects, with the potential for skin paddles up to 26 by 12 cm. Furthermore, harvest of the sixth, seventh, or eighth ribs based off intercostal perforators permits reconstruction of bone defects. Together, the latissimus-serratus unit provides the potential to use large amounts of skin, muscle, or bone in a fashion easily tailored to the reconstructive need.

  Latissimus dorsi flaps. A: A latissimus dorsi free flap has been placed over the posterior aspect of the skull to reconstruct a defect resulting from removal of a large arteriovenous malformation. B: Tissue expanders have been inserted through zigzag incisions. C: Following expander removal, the skin of the free flap is excised, and hair-bearing scalp is advanced into the defect.

• Rectus flap: The rectus abdominis flap has also been used extensively, with or without a skin paddle. Unlike with the serratus or latissimus flap, the patient does not need to be repositioned.[20] The vascular supply is reliable and supplies abundant tissue for coverage of up to half of the scalp. When harvested as a musculocutaneous flap, it carries considerable bulk, potentially too much bulk for the scalp. However, free rectus muscle using skin grafts for coverage provides good contour and bulk.[21] A possible disadvantage of the rectus free flap is the potential for abdominal wall hernia at the donor site.

• Free flaps: These provide for single-procedure closure of large defects or complicated wounds involving scalp and bone. They can also provide improved wound healing in the setting of radiation or infection. However, they are time-consuming and expensive, and they all involve at least some donor site morbidity. Therefore, they should be reserved for appropriate situations when local flaps, skin grafting, or healing by secondary intent are not options.

 A literature review by Sosin et al indicated that older age is not associated with an increased prevalence of mortality or of catastrophic flap complications in patients who undergo microvascular free-flap reconstruction of complex scalp defects. The study, which included a total of 112 patients (from 45 reports) aged 65 years or older, found an overall periprocedural mortality rate of 0.9%, with flap failures occurring in 1.8% of cases (2 patients).[22]

A surgeon who has mastered scalp reconstruction is akin to a chef with a lifetime of recipes and a fine knowledge of ingredients. The perfect reconstruction for all defects simply does not exist; therefore, the perfect reconstruction for the individual defect must be tailored to each patient. Understanding anatomy, the individual patient, and the reconstructive options available is the beginning, but, like that of a great chef, the surgeon's success requires the creativity to bring each of these elements together to create a satisfied and healed patient.

A retrospective study by Janus et al indicated that in patients undergoing scalp reconstruction following oncologic resection, wound complications are more likely to occur in cases of larger, deeper defects and in patients who have undergone preoperative radiotherapy or immunosuppression. The investigators suggested that such defects are best managed with more advanced reconstructive procedures (eg, free tissue transfer). The study involved 139 patients and had a mean follow-up period of 2.4 years.[23]

The use of stem cell technology holds promise for scalp reconstruction, as does the possibility of hair follicle cloning. Until these become a reality, the trend seems to be for conservative primary treatment of scalp defects followed by selective implementation of flaps, expanders, and grafts.