How to perform an archetypal Z-plasty
The Z-plasty is a surgical technique often used for burn contractures on mobile parts of the body that uses local flaps.
In a Z-plasty, a Z-shaped incision creates two convergent, triangular-shaped transposition flaps, which subsequently swap positions.
This exchange recruits adjacent tissue, increasing the length of tissue in the direction of the contracture. The angles and limb lengths of the Z-plasty determine its result and can be tailored to its intended effect, making the Z-plasty very versatile.
The asymmetrical Z-plasty is also known as a ‘banner flap’, as the triangle of healthy tissue resembles a ‘banner’.
You can use a Z-plasty to reposition misaligned tissues, redistribute tension and lengthen scars. Z-plasties are often used for burn contractures on all mobile parts of the body (the neck, axilla, elbow crease, hands, groin, knees, ankles etc.).
Scar contractures can vary from a single strand to a large three-dimensional area. This variation calls for different approaches. Symmetrical Z-plasties in burn contracture treatment are often very effective for single-strand contractures.
Example of a contracture of the axilla
You should always assess tissue slack when designing a Z-plasty, as it determines the maximum angle and length of the Z-plasty limbs.
The larger the angle and the longer the limbs, the greater the lengthening. But this requires more dissection, and more slack has to be available.
In a classical linear band contracture with an equal amount of non-affected skin on both sides, a symmetrical Z-plasty with angles between 50° and 70° provides the best results.
A 60° Z-plasty provides a length increase of approximately 75% of the central limb, though this increase in length is only possible if there is sufficient tissue slack available in the direction perpendicular to the contracture. This means that the sides of the triangles should not be designed longer than the amount of this tissue slack + 33% of the slack.
For example, to design a 60° Z-plasty with limbs of 4cm, you will need 3cm slack in the direction perpendicular to the central limb.
In practice, the real length gained by a Z-plasty is often less than the theoretical gain indicated by geometry. The elasticity of the skin plays an important role here: the better the elasticity of the adjacent skin, the greater the amount of length gained.
Lengthening effect in a Z-plasty
In addition to the direct lengthening effect, even more lengthening may be gained over time, for up to 1-2 years after the procedure.
In cases where there is little tissue slack and a relatively long contracture, multiple Z-plasties are indicated. A singular large Z-plasty often provides a greater increase in length than multiple, smaller Z-plasties of the same total length. This means that if there is adequate slack, one larger plasty is better.
Avoid angles less than 30° and greater than 75°:
<30˚ will compromise vascularity of the flap tips.
>75˚ will create standing cutaneous deformities (dog ears) that require excision at a later stage. This is because the tetrahedral effect of the Z-plasty becomes more evident with increasing angles.
The three-dimensional characteristics of a Z-plasty
A Z-plasty has a natural tendency to provide depth in addition to length – this is its tetrahedral effect. A tetrahedron, also known as a triangular pyramid, is a shape characterized by four triangular surfaces, four corners, and six edges.
The tetrahedral effect is most evident when conducting a Z-plasty on non-elastic materials such as neoprene or paper. When conducting a Z-plasty on an elastic cutaneous surface, this depth is witnessed less clearly because the skin stretches and shapes itself to follow the body contours.
However, in specific areas such as an axillary or interdigital fold, you can put the tetrahedral effect to use by adding depth to the flexor crease over the affected joint when performing a release of a burn contracture.
Due to the three-dimensional tetrahedral effect of the Z-plasty, the tissue does not fit into a two- dimensional plane. This means closing a Z-plasty in a flat, two-dimensional configuration gives rise to dog ear deformities – a characteristic bunching of excess tissue above the surface of the skin at the end of a scar after wound closure.
This guidance covers the Z-plasty procedure from preparation, including the surgical instruments you need, to post-operative care and the management of complications.
Preparing for a Z-plasty
|Surgical Pen||Use a good quality water resistant marker. Making a preoperative drawing is an essential part of the procedure.|
|Ruler||Measures the slack and the length of the limbs of the Z-plasty to make sure they are the same length; a protractor can be useful but most surgeons can estimate the angles adequately by eye.|
|Scalpel||Usually with a #10 or #15 blade, depending on the size of the Z-plasty.|
|Dissecting forceps||Such as Adson or other fine tissue forceps.|
|Handheld retractors||Such as small single toothed skin hooks for small Z-plasties, or Senn retractors for larger Z-plasties.|
|Scissors||Such as Metzenbaum or Iris.|
|Mono or bi-polar electrocautery||This equipment is not always essential when using jungle juice, but it can be helpful if available.|
|Needle holders||Any standard needle holder.|
|Sutures||A non-absorbable, monofilament suture will usually suffice, though larger Z-plasties under a lot of tension may require an absorbable suture in the dermal plane.|
Marking the flap design
Before marking the flap, it is essential to determine the line of maximum tension (the direction of the contracture). You can do this by extending the affected joint or body part, then determining the direction and amount of slack using the pinch test.
After assessing the affected area, mark the design of the Z-plasty. The archetypal Z-plasty consists of a central limb, typically in line with the scar (shown as a-b in the figure) and two peripheral limbs of equal size at an angle of 60° (a-c and b-d in the figure).
You can perform a Z-plasty under local, regional, or general anesthesia, depending on the location of the contracture, the estimated size and extent of the surgery, and patient characteristics.
For example, WALANT (Wide Awake Local Anesthesia No Tourniquet) is suitable for a small Z-plasty to release a webspace contracture in an adult, while you should use general anesthesia for multiple Z-plasties on a major burn contracture in a child.
When using local anesthetic, anesthetize first, then disinfect and drape. This ensures that the anesthetic has sufficient time to work properly.
Even if the procedure is performed under general or regional anesthesia, infiltrate the operative site with local anesthetic and adrenaline/epinephrine. This will greatly reduce the bleeding during the operation, make the dissection easier, and provide postoperative pain relief. Allow 30 minutes for the adrenaline/epinephrine to have the optimal effect and use a long-lasting local anesthetic agent for optimal postoperative pain relief.
The positioning of the patient depends on the location of the burn contracture.
Sterilization and dressings
Make sure that the entire site is disinfected and that the sterile drapes do not restrict movement, so that the affected body part can move freely during the procedure. This can help improve exposure and enables you to assess the effect of the contracture release immediately.
- Start with the central limb incision (the incision in the direction of the contracture).
- Make the incision that gives the maximal release (one of the peripheral limbs) through all the fibrotic tissue, into the subcutaneous fat down to the level of the fascia. Elevate the triangular flap between the two incisions. The depth of the dissection can be within the subcutis, or in a suprafascial plane. A subfascial plane is often not recommended because it limits the mobility and elasticity of the flap. Maintaining adequate blood supply to the flap while achieving the required mobility are also important factors to consider.
- You can now transpose the flap and determine the adequacy of the rest of the design. If the design is still adequate, continue with the next incision; if not, adjust the design.
- Once you have made all the incisions, dissect the second triangular flap so that you can transpose the flaps easily. In a well-designed Z-plasty, the flaps will almost fall into place by themselves. Make sure that the flaps are the same thickness all over, or that they become thicker at the base.
- Check for active bleeding and coagulate if necessary. Be cautious when coagulating on the skin flaps as this could damage the vascularization.
- Suture the flaps. It is best to start by putting the tips of the triangular flaps in their new position. If the flaps include a thick layer of subcutis, you can use subcutaneous sutures to minimize tension on the skin. Continue to suture one limb of the Z-plasty. You may often need to cut a small piece of (one) of the flaps to ensure that the size of flap matches the size of the defect.
- Ideally, use monofilament sutures to close the skin. In small children or difficult anatomical locations, absorbable sutures can be convenient and avoid the need for removal.
- Place a small drain, depending on the size and location.
How a contracture of the left axilla is released with a z-plasty, step-by-step.
After surgery, change the dressing after 3-5 days, or earlier if there is a risk of infection. Remove sutures after 2-3 weeks if they are non-absorbable.
If you used K-wires, remove them after 3-4 weeks due to the risk of infection. You can continue splinting for a longer period, until there is no further risk of the contracture recurring.
If the affected joint is not fixed for long enough in the position opposing the contracture, there is a high risk of the contracture recurring.
The patient should start active movement and exercises as soon as wound healing permits to maintain the range of motion (ROM) they have gained.
The availability of physical therapy makes a big difference. If physical therapy is not available, emphasize the importance of exercises to the patient and provide adequate instructions.
Continue splinting between exercises and during the night. Splinting during the night is sometimes continued for months, even after the wounds have healed fully and the affected limb has returned to normal use. Splinting works well when the skin quality is good, but it is less effective in stretching remaining scar tissue. In these cases, additional surgery to add extra tissue where needed may be more effective, followed again by appropriate positioning after the additional procedure.
Evaluation of results
Patients should continue to visit a doctor until the wound is completely healed. Measure and document the ROM preoperatively, and monitor the development of ROM postoperatively. Explain to the patient that the ROM will continue to improve for months, provided that they do their exercises. One year post-procedure, you can take the final measurement and evaluate the result together with the patient.
Management of complications
As burn scars are very fibrotic and therefore often poorly vascularized, complications in wound healing are common. Wound breakdown, necrosis, and infection are the most common complications. This is particularly true when wounds are closed under tension. If a local flap such as a Z-plasty does not provide enough tissue to close the wound without tension, we advise either adding a skin graft or accepting that the joint cannot be fully extended (yet).
You can start antibiotic treatment when indicated for infection. Treat small areas of necrosis and minor wound breakdown conservatively by cleaning the wound and applying antibacterial dressings. The small defects will heal by secondary intention and the end result will often still be adequate in terms of contracture release, so no further treatment will be required.
Surgically debride larger breakdowns with extended necrosis. If the defects are substantial (for instance a complete triangle of the Z-plasty has become necrotic), treat the area with a skin graft as soon as the wound bed allows. Without this secondary surgery, these cases will very likely end with a recurrence of their contracture.