1 Introduction topenlarge
Single subunit defects (tip or ala) that require only modest skin resurfacing and limited cartilage replacement can be resurfaced with forehead skin transferred in two stages.
However, when a forehead flap in transferred in only two stages, it is not possible to alter the inferior nose, columella, or ala at the time of pedicle transfer without devascularization.
Large deep defects which encompass multiple nasal units and require extensive replacement of cartilage support or nasal lining should be reconstructed with a full thickness forehead flap in three stages.
The forehead is thicker than nasal skin and excessive subcutaneous fat and frontalis muscle must be excised to create a skin flap of a thickness similar to that of the missing skin of the nose. Although the excessive soft tissue can be excised at the time of harvest, in larger more complicated defects it is safer to thin the excess during an intermediate operation prior to pedicle division.
This improves vascular safety and aesthetic results. The intermediate operation allows the surgeon to re-elevate the flap completely and aesthetically contour the inferior nose by soft tissue excision and cartilage modification.
The advantages of a full thickness three stage flap are:
- Maximum vascularity at the time of transfer and at the intermediate second stage operation.
- The ability to create a uniformly thin supple skin flap.
- Staged soft tissue sculpture, primary and delayed primary cartilage grafting.
- The ability to correct previous intraoperative errors of judgments or imperfections of healing prior to pedicle division.
- Modified techniques to provide vascular lining as a folded distal flap extension or as a skin graft.
Principles of reconstruction
Each defect is different but each reconstruction is simplified because the "Normal" never changes so the principles of repair remain the same. The contralateral normal remains as a visible comparison. If the contralateral normal is unavailable, the ideal is used as a guide.
The face can be described in regional units characterized by:
- Skin quality
- Border outline
- 3 dimensional contour
The principles of nasal reconstruction which apply to large deep defect which will be resurfaced with a flap are:
- Recreate nasal subunits, not just fill the defect.
- Alter the wound in site, size and depth to improve the final result
- If appropriate, excise residual normal skin within the subunit to replace missing skin as a unit, rather than as a patch
- bunit principle)
- Use the contralateral Normal or the Ideal as a guide
- Replace missing tissues exactly
- Employ surgical templates
- Build on a stable platform
Subunit principle: If a defect encompasses more than 50 % of a convex subunit – tip or ala - remaining normal skin is excised within the subunit and the entire subunit is resurfaced with a subunit flap. This positions final border scars in the junctions between adjacent subunits and harnesses flap trapdoor contraction and postoperative pin cushioning, and in combination with shaped underlying cartilage support, augments the shape of underlying cartilage support over the entire subunit.
This procedure is performed under general anaesthesia to minimize soft tissue distortion and vasoconstriction associated with local anaesthetic injection.
The fluid volume of local anaesthetic alters the dimension, thickness, and position of both the donor tissues and recipient site. The blanching caused by epinephrine will make intraoperative evaluation of tissue vascularity difficult.
2 Resection topenlarge
If an initial excision is required to treat skin cancer, the tumor is excised utilizing standard excisional margins, verified by frozen section by the operating surgeon or the operating Mohs surgeon.
3 Stage 1a: Flap template topenlarge
The subunits of the nose and regional units of the face are marked with ink.
If intact prior to skin cancer incision, a template of the nasal subunits requiring resurfacing is created using quarter inch adhesive paper tape and collodion.
If significant parts of the nose remain, a template can be made of the remaining contralateral normal nose.
If the nose is missing, a universal pattern can be used to create a template with a basic nasal dimension and outline for the future forehead flap. Prior to use, it is crimped, bent, and trimmed to conform to the defect exactly.
Excision of residual skin
If a subunit excision is planned, residual normal skin within the subunits is excised.
4 Stage 1b: Reconstruction of cartilage support topenlarge
The cartilaginous and bony framework of the nose is enveloped by the external covering skin and internal lining. This framework supports and shapes soft tissues and braces a reconstructed nose against gravity, tension, and scar contraction. If missing, nasal support must be replaced. The dimension, border outline, and shape of these bone and cartilage support grafts will re-establish the normal nasal contour.
The choice of donor material will depend on the needs of the defect:
- Graft size,
- Graft shape
- Graft rigidity
Septal cartilage is straight but of limited length and thickness.
Ear cartilage is relatively soft, curved, but limited in availability.
Rib cartilage is available in large quantity, thickness, has rigidity, and can be shaved into thinner more bendable strips with suture material.
Grafts are fixed with sutures to remaining nasal support structures and fixed to one another to recreate a rigid nasal framework to support and shape the nose.
The volume, dimension, and contour of the tip subunit depend on the underlying cartilage framework.
Parts or all of the normal tip support may be missing. Each component must be reconstructed to support, shape and brace the reconstructed tip postoperatively
Septal, ear, or rib cartilage is used to reconstruct the tip complex to replace the missing medial and lateral crura as needed.
If the underlying tip cartilages are intact, it is useful to improve tip support by fixing a columella strut between the intact medial crura.
If the domes and anterior medial crura are missing, a columella strut is fixed between the remaining medial crura to restore central support.
If the tissue injury is larger, a longer columella graft can be placed and fixed to the nasal spine with a suture to augment central tip support.
Tip shape and support can be restored with a Peck graft to provide tip volume, and projection or with anatomic tip replacements, often combined with alar margin rim grafts to support the soft triangles. (Preparation and insertion of alar margin rim grafts is shown below)
Alternatively, the tip can be rebuilt with anatomically shaped tip grafts – middle and lateral crura replacements of ear or rib cartilage that are bent with sutures to mimic the normal anatomy. (Preparation and insertion of alar margin rim grafts is shown below)
Normally the ala contains no cartilage, but an alar margin batten graft must be placed within a large defect of the ala to support, shape and brace the reconstructed ala postoperatively.
Although septal or rib cartilage can be utilized, conchal cartilage is ideal because of its natural curvature, if rib cartilage is not otherwise needed.
The conchal cartilage is harvested through a postauricular incision.
The alar template is used as a guide to create a nostril margin graft of the correct dimension and border outline.
The dimension of the graft is extended a few mm medially and laterally to allow its fixation in a small subcutaneous pocket created laterally within the soft tissues of the alar base and sutured medially to the tip cartilage remnants or their replacements.
The ear cartilage graft is fixed into the lateral pocket with a percutaneous quilting suture laterally and sutured medially to the tip complex. The graft itself is sutured to the underlying raw lining surface to support it.
When central septal support is intact, onlay cartilage grafts can be placed to augment the height of the nasal bridge and establish the correct width.
These onlay grafts are secured in soft tissue pockets under the remaining nasal skin and fixed with sutures to the underlying dorsum.
If central support is missing, but a significant part of the deeper septum remains intact, the remaining septum can be rotated out of the pyriform aperture as a septal composite flap to restore a basic dorsal platform and a small amount of lining if needed.
Additional onlay grafts are added to create further dorsal height and shape.
More commonly, if the central septal support is missing, especially when the septum is largely absent, a rib graft is positioned as a cantilever graft to project from the remaining radix and nasal bone. This is fixed with one or more screws to the residual nasal bones.
The dorsal graft may also be supported by a reconstruction plate.
When the nasal bones or upper lateral cartilages are missing, a side wall bracing graft is placed to support and shape the lateral nasal wall, maintain the airway, and prevent retraction of the ala superiorly.
The graft extends from the pyriform aperture anteriorly to the central dorsal support and inferiorly to the alar graft. It is fixed with sutures to these support structures.
5 Stage 1c: Transfer of a paramedian forehead flap topenlarge
Outline of paramedian forehead flap
The template is positioned under the hairline directly superiorly to its supratrochlear pedicle, which is located a few mm lateral to the frown crease (verified by doppler).
The outline and the dimension of the flap will be designed to resurface parts or all of the dorsum, tip, and ala depending on the defect.
The paramedian flap is perfused by the supratrochlear vessels and can be based on either side of the forehead. Unilateral defects are more easily resurfaced with the ipsilateral flap because its pedicle is closer to the defect.
Either the right or left pedicle can be chosen for midline defects.
Centered over the supratrochlear vessels, the flap’s pedicle is drawn inferiorly through the medial eyebrow, narrowing to 1.2 to 1.5 cm in width at the pedicle base.
The border of the flap is incised, elevating the flap from distal to proximal over the periosteum to its pedicle base, with the underlying tissues and frontalis muscle, as a full thickness flap without thinning.
This maintains the skin vascularity through the deep dermis, frontalis muscle and axial supratrochlear vessels.
The flaps base is incised through the medial eyebrow separating the corrugator muscle until it can be rotated medially to cover the nasal defect without tension.
Closure of donor site defect
A scalp dog ear is excised and the forehead is widely undermined.
The forehead defect is closed in layers.
If the superior aspect of the defect cannot be closed primarily, it is allowed to heal secondarily over several weeks. The open area is covered with a petrolatum gauze for one week.
The forehead flap is sutured into the recipient site with a single layer of sutures.
A full thickness skin graft harvested from the groin is placed on the raw deep surface of the pedicle for cleanliness.
6 Stage 2: Thinning of the flap topenlarge
One month later the bulky flap has healed to the recipient site. Because of its elevation and rotation it is effectively physiologically delayed, augmenting its blood supply.
The borders of the flap are incised and the flap is completely elevated off the recipient site with 2-3 mm of subcutaneous fat, creating a uniformly thin skin flap for nasal cover.
Underlying excess subcutaneous fat and frontalis muscle are completely exposed and are excised to debulk the nose and sculpt a nasal shape into the previously transferred tissues.
Old cartilage grafts can be removed, reshaped or repositioned as necessary to improve the hard tissue framework. An imperfectly designed or malpositioned graft can be revised.
The thin skin flap is returned to the recipient site fixing its cutaneous surface to the underlying bed using percutaneous quilting sutures and its peripheral borders with single layer skin sutures.
7 Stage 3: Pedicle division topenlarge
One month later the regional units of the nose are marked with ink.
The site of pedicle division is marked, leaving excess tissue that can be trimmed at the time of fine tuning the reconstructed subunit.
The pedicle is divided.
The skin of the nasal inset is elevated with 2-3 mm of subcutaneous fat over the superior aspect of the reconstructed nose.
A forehead flap can be extensively re-elevated towards the nostril margin and the columella inset. Because the operation is performed under general anaesthesia without local anaesthesia, the flap colour and capillary refill can be evaluated.
Underlying subcutaneous fat or excess cartilage over the superior nose are excised to sculpt the sidewall, dorsal contour, and deepen the alar crease.
Excess forehead skin is trimmed and the forehead skin inset with percutaneous quilting sutures and a single layer skin closure.
The inferior part of the forehead scar through the medial eyebrow is reopened.
The skin of the proximal forehead pedicle is elevated with several mm of subcutaneous fat from the underlying excess soft tissue and previous skin graft of the proximal pedicle.
The excess underlying soft tissue bulk is excised.
The skin of the proximal pedicle is trimmed, returning the medial eyebrow to its normal position and inset as a small inverted V whose scars simulate the normal frown crease.
It is fixed in place with a temporary quilting suture and a layered skin closure.
Pre-and postoperative photographs of a large partial thickness defect repaired with a three stage forehead flap.