Residency · Residency · Plastic Surgery

Scalp and Calvarium Reconstruction

Introduction

Scalp and calvarium reconstruction addresses defects from trauma, tumor excision, radiation necrosis, infection, and congenital anomalies. The scalp has a rich vascular supply but limited laxity, making reconstruction of large defects challenging. Defect classification considers involvement of skin, galea, pericranium, bone, and dura. Reconstruction must achieve watertight dural closure, durable soft tissue coverage, and acceptable cosmesis. A systematic approach from local tissue rearrangement to free tissue transfer guides surgical planning.

Anatomy

Scalp Layers (SCALP Mnemonic)

Skin: thick (3-8 mm), hair-bearing; contains dense follicular units (highest density frontally). Connective tissue (subcutaneous): fibrous septa tethering skin to galea; contains major blood vessels and nerves. Aponeurosis (galea aponeurotica): tough fibrous layer continuous with frontalis anteriorly and occipitalis posteriorly; laterally continuous with temporoparietal fascia. Loose areolar tissue: avascular plane allowing scalp mobility; surgical dissection plane for scalp flap elevation. Pericranium (periosteum): adherent to calvarium; provides a thin but vascularized tissue layer for grafting.

Vascular Supply

Five paired arteries provide redundant blood supply, allowing flap design based on any single vessel: Supratrochlear artery: terminal branch of ophthalmic artery; exits 1.7-2.2 cm lateral to midline. Supraorbital artery: exits the supraorbital foramen/notch; supplies anterior scalp. Superficial temporal artery (STA): terminal branch of external carotid; supplies temporal and parietal scalp.

Posterior auricular artery: branch of external carotid; supplies mastoid and posterior scalp. Occipital artery: branch of external carotid; supplies posterior scalp. Extensive anastomotic network between these vessels allows large rotation flaps with single-pedicle blood supply.

Calvarium Anatomy

Three layers: outer table (cortical), diploic space (cancellous/marrow), inner table (cortical). Total thickness: 6-10 mm in adults; thickest at the occipital and frontal bones. Dura mater adherent to inner table; dural defects require repair to prevent CSF leak and meningitis.

<image>Cross-sectional anatomical illustration of the scalp showing all five layers (SCALP mnemonic) with labeled structures, the underlying calvarium with outer table, diploe, and inner table, and the dura mater beneath, with the five arterial supply systems marked at the periphery</image>

Defect Classification and Assessment

Tissue Depth Classification

Type I: skin and subcutaneous tissue only; pericranium intact. Type II: full-thickness scalp including pericranium; intact calvarium. Type III: scalp and calvarium defect; intact dura. Type IV: composite defect including scalp, calvarium, and dura (with or without brain exposure).

Key Assessment Parameters

Defect size and location: anterior defects more cosmetically significant; temporal defects near facial nerve. Etiology: tumor defects may require surveillance (avoid bulky reconstruction over potential recurrence sites); radiation-damaged tissue has poor healing capacity. Intact pericranium: critical determinant; its presence allows skin grafting; its absence necessitates flap coverage. Exposed hardware, dura, or brain: requires vascularized tissue coverage. Patient factors: prior radiation, smoking, immunosuppression, anticoagulation.

Reconstructive Options

Skin Grafts

Split-thickness skin graft (STSG): applicable only when a vascularized bed exists (intact pericranium or healthy granulation tissue). Not suitable over bare cortical bone, exposed dura, or irradiated tissue. Integra dermal regeneration template: can be placed over calvarium with outer table removal (exposing diploic bleeding); followed by delayed STSG at 3-4 weeks.

Local Flaps

Primary closure: possible for defects <3 cm due to limited scalp laxity; wide undermining in the subgaleal plane increases closure potential. Galeal scoring: parallel incisions through the galea at 1 cm intervals perpendicular to the line of closure increase scalp flap extensibility by 1-2 cm per score. Rotation flaps: Orticochea three-flap technique for larger defects; the length of the rotation arc should be 4-6 times the defect diameter. Advancement flaps: bilateral advancement (H-plasty) for midline defects; back-cuts and Burrow's triangles facilitate advancement. Transposition flaps: for defects adjacent to non-hair-bearing skin; maintains hair-bearing coverage.

Regional Flaps

Temporoparietal fascia (TPF) flap: thin, well-vascularized fascia based on superficial temporal artery; excellent for coverage of exposed bone or hardware; covered with STSG. Pericranial flap: based anteriorly on supratrochlear/supraorbital vessels or posteriorly on occipital vessels; provides thin vascularized coverage for small to moderate cranial defects. Trapezius myocutaneous flap: pedicled on transverse cervical artery; reaches occipital and posterior scalp defects.

Free Flaps

Indicated for large defects (>100 cm²), irradiated tissue, or when local options are exhausted. Latissimus dorsi free flap: large muscle coverage (up to 20 x 40 cm); reliable pedicle (thoracodorsal artery); covered with STSG; most commonly used free flap for scalp reconstruction. Anterolateral thigh (ALT) free flap: versatile; can be thinned; provides moderate surface area coverage. Radial forearm free flap: thin, pliable; good for smaller defects requiring thin coverage.

Omentum free flap: conforms to irregular cranial contours; covered with STSG; useful for infected or irradiated fields. Recipient vessels: superficial temporal artery (most common), occipital artery, or facial artery (with vein grafts if necessary).

<image>Surgical planning illustration showing multiple reconstructive options for scalp defects of increasing size: primary closure with galeal scoring for small defects, large rotation flap for medium defects, and latissimus dorsi free flap with split-thickness skin graft for extensive defects</image>

Calvarium Reconstruction

Bone Reconstruction Options

Split calvarial bone graft: gold standard for autologous cranial bone reconstruction; harvested from parietal bone (opposite side); provides outer table graft with native contour. Titanium mesh: prefabricated or custom; lightweight; allows postoperative imaging; risk of exposure through thin soft tissue. PEEK (polyether ether ketone) implants: custom-fabricated from CT data; excellent contour matching; bioinert; expensive. Polymethylmethacrylate (PMMA): inexpensive; moldable intraoperatively; exothermic setting reaction requires irrigation to prevent thermal injury. Hydroxyapatite cement: osteoconductive; biocompatible; limited structural strength for large defects.

Dural Repair

Primary dural closure when possible; watertight closure essential to prevent CSF leak. Dural substitutes: autologous pericranium, fascia lata, or alloplastic materials (bovine pericardium, synthetic dural grafts). Lumbar drain placement for 3-5 days postoperatively reduces CSF pressure at repair site. Collaboration with neurosurgery is mandatory for defects involving the dura or brain parenchyma.

Complications

Hematoma: subgaleal hematoma most common; drain placement and compressive dressings reduce risk. Infection: risk increased with alloplastic materials, radiation, and CSF leak; Staphylococcus aureus most common pathogen. CSF leak: from inadequate dural repair; may present as rhinorrhea, wound drainage, or meningitis. Flap necrosis: partial or complete; more common with local flaps in irradiated tissue.

Hardware exposure: titanium mesh or PEEK implants through thin soft tissue; may require flap coverage. Alopecia: at donor sites for rotation flaps; along suture lines; may require tissue expansion or hair transplantation for cosmetic revision.

<image>Intraoperative photograph sequence showing calvarium reconstruction: (A) full-thickness cranial defect after tumor removal with exposed dura, (B) dural repair with pericranial graft, (C) titanium mesh cranioplasty secured to calvarium edges, (D) latissimus dorsi free flap providing soft tissue coverage over the construct</image>

Key Clinical Pearls

Always assess the depth of the defect systematically: intact pericranium allows skin grafting; absent pericranium requires flap coverage. Galeal scoring is a simple technique that significantly increases the reach of local scalp flaps. The rich anastomotic blood supply of the scalp allows large rotation flaps based on single named vessels. Free tissue transfer (latissimus dorsi) is the workhorse for large, irradiated, or composite scalp defects. Neurosurgical collaboration is essential for any defect involving the calvarium and dura; watertight dural closure with CSF diversion prevents devastating infectious complications.

References

1. Leedy JE, Janis JE, Rohrich RJ. Reconstruction of acquired scalp defects: an algorithmic approach. Plast Reconstr Surg. 2005;116(4):54e-72e.
2. Desai SC, Sand JP, Sharon JD, Branham G, Nussenbaum B. Scalp reconstruction: an algorithmic approach and systematic review. JAMA Facial Plast Surg. 2015;17(1):56-66.
3. Afifi AM, Djohan RS, Hammert W, Papay FA, Barnett AE, Zins JE. Lessons learned reconstructing complex scalp defects using free flaps and a cranioplasty in one stage. J Craniofac Surg. 2010;21(4):1205-1209.
4. Chao AH, Yu P, Skoracki RJ, Demonte F, Hanasono MM. Microsurgical reconstruction of composite scalp and calvarial defects in patients with cancer: a 10-year experience. Head Neck. 2012;34(12):1759-1764.

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