A flap is used when simpler closure techniques, such as secondary intention, primary closure, or skin grafts, will produce a result that is functionally or cosmetically unacceptable. Flaps can reduce and redirect tension, making them an indispensable tool in wound closures. By using the nearby tissue, flaps allow for excellent skin color, texture, and thickness to match the recipient site. A skin flap uses a reservoir of tissue laxity to close a surgical defect known as the primary defect. The operative wound created by the flap is known as the secondary defect. Flaps, unlike grafts, remain attached to a vascular supply known as a pedicle. Blood supply classifies flaps. Axial flaps are supplied by a named artery, whereas random pattern flaps are supplied by the dermal plexus or unnamed musculocutaneous arteries.
It is common for flaps to be classified base on the primary motion of the flap. There are 3 basic types of tissue movement: transposition, advancement, and rotation. Transposition flaps incorporate noncontiguous skin into a primary defect by lifting the flap over normal skin into a defect. Advancement flaps recruit adjacent tissue to close a defect in a linear direction. Rotation flaps pivot adjacent tissue around an axis to close a primary defect, essentially rotating skin into the defect.
Rotation flaps should be used when other simpler types of closure fail to provide adequate functional and cosmetic result. Rotation flaps, despite their length and arc, can be used in many locations. Rotation flaps are most commonly used for lesions on the lateral face, cheeks, chin, and scalp. Rotation flaps are particularly useful for redirecting tension around a free margin to prevent distortion. Examples of this would include rotation flaps used for the eyebrows or lips. There are also several named rotation flaps that are useful in specific situations that will be discussed below.
In addition to the indications for a rotation flap, it is essential that the surgeon consider the contraindications for a rotation flap. Flaps are contraindicated if the malignancy is not completely cleared. Failure to achieve clear margins before performing a flap may have disastrous outcomes. Persistent tumors may grow unrecognized beneath the flap for years. The tumor can spread along the plane of undermining, which can further add to the morbidity of the malignancy. For this reason, most flaps are performed following Mohs micrographic surgery as this modality is highly effective in obtaining clear margins. Additionally, the patient should be evaluated for any signs of malignancy within or near the flap for the same reasons as above. Surgeons should be cognizant that future closure options for nearby malignancies can be severely limited due to the placement of a flap and should adjust their closure techniques accordingly.
Proper patient selection is essential in assuring quality outcomes. The patient’s functional status or access to care may obligate the use of different closure techniques depending on the situation. Vascular supply and durability of a flap can also be very patient specific. For example, a pedicle taken from within a scar or area of radiotherapy may have an impaired vascular supply, and therefore other reconstructive options should be considered.
Relative contraindications include the risk of hemorrhage and smoking status. Smokers, in general, are at increased risk for complications following surgery. Specifically, they are at increased risk of flap necrosis, which means that other closure modalities may be preferable due to this risk. Smokers should be advised to stop smoking at least 2 weeks before and 1 week afterward to help maximize flap survival. Patients on anticoagulant therapy are at increased risk of perioperative and postoperative bleeding, which can impair flap viability. Current recommendations are to continue prescribed anticoagulant therapy for cutaneous procedures. Surgeons should be mindful of these risks in planning wound closure as well as intraoperatively to help mitigate this risk.
Rotation flaps are created by using an arcuate or curvilinear incision. Although they are referred to as rotation flaps, in practice, these flaps combine both advancement and rotation to pivot a flap into place (see Figure 1). Due to their arcuate shape, solitary rotation flaps are ideal for closing triangular defects. Closures using multiple rotation flaps, in contrast, do not need to be enlarged into a triangle. Given a circular defect being closed with a single rotation flap, the defect must be enlarged into an isosceles triangle along the arc of the tissue movement. The apex of the triangle must point to the center of the arc, and the base of the triangle must be continuous with the arc of the flap. The isosceles triangle should ideally have a length 2 times the base of the triangle.
Rotational flaps are unique in that they are subject to a tethering effect known as pivotal restraint. Therefore, the rotation flaps can fall short by not completely covering the most distal edge of the primary defect. The point of pivotal restraint, located at the end of the incision, should be undermined widely to enhance the primary motion of the flap. Wide undermining may be all that is required to close the wound with minimal tension. Undermining is typically performed in the subcutaneous plane, with several exceptions. Some notable exceptions include: the nose should be undermined in the submuscular plane; the scalp should be undermined in the subgaleal plane; the periorbital area should be undermined above the orbicularis oculi, and the ear should be undermined just above the perichondrium. Caution must be used in undermining since excessive undermining can separate the pedicle from the perforating arteries supplying the pedicle base.
Pivotal restraint should be considered in the planning stages of the flap. Pivotal restraint is addressed by making the radius of the arc greater than the length of the defect. Some authors suggest the radius should range from 1 to 2 times the length of the defect. This increase in radius makes the arc taller than the defect and effectively compensates for the loss of length as the flap is rotated. Another option would be to add more of an advancement component to the flap. However, this increases the tension on the tip of the wound, which can impair the vascular supply to the tip of the flap. Lastly, adding a back cut to the far end of the incision brings the pivot point closer to the primary defect and is an effective solution to pivotal restraint. However, a back cut will decrease the width of the pedicle, which can compromise the vascular supply of the flap. The degree of tissue movement is proportional to the size of the back cut, so the surgeon must balance the need for additional movement with the size of the pedicle. A rule of thumb for facial flaps is to keep the ratio of length to width of the pedicle to less than 4:1. The face is a vascularly privileged site and therefore can support flaps of this length. However, flaps located on the body should have a length to width ratios of less than 2:1. This is not a common issue since rotation flaps tend to be shorter flaps, but this should be considered when making a back cut.
The length of the arc should be greater than 90 degrees to properly distribute tension. Extension beyond 90 degrees has minimal effect on tension but does allow for a smaller standing cutaneous deformity. Ideally, the arc of a rotation flap should be between 90 to 180 degrees in length. Rotation flaps with arcs less than 90 are subject to higher tension. An arc of greater than 180 degrees changes the vector of tension in a counter-productive manner, usually adding tension in a vector parallel to primary wound closure. The vector of tension for a rotation flap is directed perpendicularly along the arc of the incision, which, in a classic rotation flap, is perpendicular to the tension vector for primary wound closure. Like most flaps, the area of greatest tension is at the closure of the secondary defect. For a pure rotation flap, the area of maximal tension is directed perpendicular to the arc of rotation between 90 to 135 degrees away from the defect. If there is an advancement component to the flap, the point of maximal tension will be at the tip of the rotation flap. The length and curve of the incision may run perpendicular to relaxed skin tension lines or cross into other cosmetic units, which can be limiting factor in using this type of flap. However, the length of the incision may be used advantageously to recruit distant tissue reservoirs or to hide standing cone deformities in less prominent locations.
Due to the primary motion of the flap, a standing cutaneous deformity may be produced on the end of the arc, meaning a dog ear may form along the arc on the opposite side of the primary defecting. A common way to address this is to take a burrow’s triangle at some point along the outside of the arc. In some instances, especially with longer incisions, the defect can be serially halved using sutures to compress and distribute the excess tissue over the length of the wound. If a back cut is necessary, it can be combined with a burrow’s triangle to create a Z-plasty at the end of the arc.
Double Rotation Flaps
Double rotations flaps are commonly used for defects that are too large to close with a single rotation flap. Typically, these flaps are used on the scalp or around free margins. These flaps produce a combination of both advancement and rotation which can make categorization confusing. The design of a double rotation flap starts with a single point on the defect with an arc forming in opposite directions forming a semicircle with a defect in the apex of the arc (See figure). Each flap is mobilized and rotated in opposite directions. One flap moves clockwise and the other moves counterclockwise. An analogy for this type of movement would be closing a book, where both sides are moving equally to meet in the middle. It is important to note that this defect is enlarged into a triangular defect, unlike the other double rotation flaps discussed below.
O to Z Flap
The O to Z flap is a double rotation flap, commonly used on the central scalp or large lesions on the trunk. Defects on the lateral scalp are typically closed with larger solitary rotation flaps. Scalp tissue can be very inelastic, which may necessitate the use of very large flaps and long incisions. The scalp is an ideal location for this flap because the patient’s hair can provide excellent camouflage for these incisions. The flaps start at opposite ends of the defect with both incisions taking off in the same manner, either clockwise or counterclockwise. Because the incisions are at opposite sides of the defect, the curve of the arcs are in different directions (see figure). Each flap will rotate to cover half of the lesion with minimal enlargement of the primary defect needed. In fact, the tip of each flap will need to be trimmed to inset the flaps properly. Typically, each arc is 180 degrees and rotates tissue in the same direction, meaning both flaps will either rotate in a clockwise or counter-clockwise fashion. The final wound assumes an “S” like configuration. A variation of on O to Z flap uses three or more rotation flaps. As in the O to Z flap, all of the flaps are rotated in the same direction. Due to the configuration of the closure, this flap is called a pinwheel flap. Both the O to Z and the pinwheel flap can incorporate a variable amount of rotation and advancement. For example, the pinwheel flap when it incorporates mostly advancement will appear similar to a Mercedes logo. (needs rewording) The pinwheel flap is also useful for scalp and truncal defects.
Modified Peng Flap
The Peng flap is used for medium to large nasal tip defects. The original Peng flap was primarily an advancement flap, but the Peng flap can be modified to add more of a rotational component. This is essentially a double rotation flap where the pivot point is located along the midline at the nasal root. Rotation flaps are taken from each nasal sidewall and rotated toward the midline to cover the defect. Some pitfalls to this flap include distortion of the symmetry of the nose if the defect is not centrally located. It can also lead to the lifting of the nasal tip or ala. Depending the degree of cheek advancement, tenting may be noted at the base of the ala, which can be corrected with an incision along the alar groove. This flap may be used as a single stage alternative for defects requiring a paramedian forehead flap.
Unique Rotation Flaps
Dorsal Nasal Rotation Flap
Rieger first proposed the dorsal nasal rotation flap in 1967. This flap is used for larger defects less than 2 to 3 cm in size on the distal nose. This flap recruits a reservoir of tissue in the glabella and rotates this tissue along with the nasal dorsum inferiorly to cover the primary defect. The arc of this flap runs along the alar crease superiorly along the nasal sidewall and into the glabella. If the further rotation is required, a back cut can be made along the contralateral side, but should not extend beyond the level of the medial canthus. Marchac et al. described an axial pattern flap using perforators from the angular artery. The vascular supply for this pedicle comes from the medial canthus. Thus back cuts beyond the level of the medial canthus should be avoided as this can impair the vascular supply of the flap. Patient selection is important in this flap as some patients may not have the tissue laxity necessary to execute the flap. It can cause a loss of nasal symmetry, lifting of the nasal tip and ala, and distortion of the ala, if it is not properly designed.
The Mustarde flap is used for defects of the lower eyelid and cheek. This flap disperses tension in a horizontal plane and is used to prevent excessive tension on the lower eyelid and subsequent ectropion. The defect is enlarged into a triangular shape, but if the lesion is more than half the cosmetic subunit, it may be advisable to remove the entire subunit, using the flap to recreate the subunit. The incision is directed laterally from the defect, along with the lower eyelid. The arc after the lateral canthus is directed superolaterally in the temple region. This exaggerated superior movement is made to counteract the increase in tension induced by pivotal restraint due to the primary motion of the flap. The incision then descends along the preauricular skin. This is a large flap, and despite planning for pivotal restraint, may still induce ectropion due to the weight of the flap. Tacking sutures are a frequently used option to offset the weight of the flap. Tacking sutures can be placed into the periosteum along the lateral border of the orbit. The primary motion of the flap can rotate the beard and sideburns onto the cheek making this closure less preferable in male patients.
A similar design, known as the Tenzel flap, is a myocutaneous rotation flap used for defects of the lower eyelid. This is a smaller flap compared to a Mustarde flap which incorporates some of the orbicularis oculi into the flap. The incision is carried along the lower eyelid and proceeds superiorly past the lateral canthus, in a similar fashion to a Mustarde flap. However, the Tenzel flap does not extend as far as the Mustarde flap. This flap relies on the rotation of the temporal skin and usually requires lysis of the lateral canthal tendon. Since this flap is smaller in size compared to a Mustarde flap, it will not need tacking sutures.
The spiral flap has several proposed uses, including defects on the lower eyelid and ventral fingertip. However, the original indication for a spiral flap was for deep defects along the alar groove measuring up to 1.5 cm in size. This flap is useful for the ala because it has the potential to preserve the alar groove or sulcus. The flap is incised similarly to a classic rotation flap. However, because of the spiral shape, there are additional variables to consider including the curvature of the spiral. Defects involving the alar groove should use a spiral where the width of each level of the spiral is the same. This will produce a prominent inward bend that will recreate the groove. Defects along the alar crease will require a shallower depression and should use an algorithmic spiral where each level of the spiral becomes progressively larger. The first arm of the spiral is responsible for the recreation of the alar crease or groove. To properly align this, the first arm of the spiral must have a width equal to the distance from the inferior aspect of the defect to the desired location of the alar groove. This arm will be sutured to rest of flap, thus initiating the spiral. The reservoir for this flap can be taken from the nasal sidewall or an incision directed along the alar groove. The flap will move anteriorly and superiorly or inferiorly depending on the location of the tissue reservoir. The take-off point of the incision is along the inferior aspect of the defect with the arc extending anteriorly. As mentioned above, the first arm of the spiral is sutured to the flap to initiate the spiral and recreate the alar crease or groove. The second stitch anchors the flap to the point of maximal tension along the inferior aspect of the defect.
The cervicofacial flap is used for very large defects of the cheek. The flap is created similarly to a Mustarde flap with the incision carried further onto the neck. The incision runs from the superior aspect of the defect superolaterally to the preauricular cheek. The incision is then extended crossing under the ear and inferiorly along the lateral neck. The arterial supply is from perforators of the facial and submental arteries. The cervical skin is an excellent source of redundant tissue and allows for proper tissue matching compared to a graft. As in the Mustarde flap, cervicofacial flaps can rotate facial hair from the beard and sideburns onto the cheek. This is also a very large flap which may necessitate the use of tacking sutures.
There are a number of complications that can occur following a rotation flap. Most complications can be avoided with cautious planning and sound technique. Excessive tension or wound contracture can result in distortion of surrounding tissue. Rotation flaps that do not properly disperse tension vectors can distort sensitive structures such as the mouth and eyelid, producing an ectropion or eclabium.
If a flap is not properly sized compared to the defect, the flap can result in a trapdoor deformity or pincushioning. A trapdoor deformity makes the healed flap appear as a depressed area compared to the surrounding tissue. This is due to a lack of supporting tissue under the flap or from excessive thinning of the flap. Pincushioning, on the other hand, presents with a noticeably raised flap compared to the surrounding tissue. Pincushioning is due to excessive tissue. This can be from a flap that is comparatively too thick or with an oversized flap that was not adequately trimmed to fit into the defect.
Flap necrosis results from ischemia of the distal end of the flap as a result of impaired blood flow. Blood flow within a flap can be compromised by; making the pedicle too small to the support the flap, making the flap too thin which disrupts the dermal plexus, or by excessive undermining which disrupts perforating vessels feeding the pedicle. Flap necrosis can present as sloughing of the epidermis or as an eschar. It is difficult to assess how much of the flap is viable when an eschar is present, but it is imperative to avoid debriding the area until the wound has healed. It is possible that only the epidermal portion of the flap necrosed and debriding the flap can disrupt viable tissue. Even in cases where the flap has necrosed, the eschar over the wound will act as a biologic dressing that will allow the wound to heal by secondary intent.
As with any surgery, wound infection is a potential complication. If a surgical site infection is suspected, the wound should be cultured, and the patient should be started on an antibiotic with staphylococcal coverage until a culture and sensitivity are available. If there is a significant amount of purulent drainage, the wound may need to be opened, cleaned, and all foreign material, such as sutures, removed.
Dehiscence can occur as a result of excessive tension or from an infection. If a wound dehisces within 24 hours after surgery another closure can be attempted, however closures after this time may increase the risk of infection. Typically dehisced wounds are allowed to heal by secondary intent with revision considered after the wound has healed.
Bleeding is another potential complication. However, most cases can be controlled with firm continuous pressure. In some instances, it may be necessary to reopen the wound to stop the bleeding. Bleeding can also result in hematoma formation. Stable hematomas can be drained or allowed to reabsorb over time. Hematomas may act as a nidus for infection, so antibiotic prophylaxis should be considered. Active hematomas, those that continue to grow, should be treated by reopening the wound to evacuated the hematoma and stop any bleeding.
With proper planning and execution, rotation flaps provide a versatile technique that can be used in a number of situations to produce excellent functional and cosmetic outcomes.