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Skin cancer surgery on referral

The introduction of the ROM flap

The reducing opposed multilobed flap repair

Reducing opposed multilobed flap repair: - a new technique for managing medium sized low leg defects following skin cancer surgery.

Abstract:

Following skin cancer excision, skin defects on the low leg between 10 and 35 mm in diameter can be problematic. Direct closure of the wound risks excessive wound tension and wound dehiscence. Skin grafts heal slowly and often remain unsightly. Traditional skin flaps have a limited role.

The Objective was to develop a random pattern skin flap that offers significant advantages over traditional techniques including grafting. The reducing opposed multilobed flap involves a series of semicircular lobes extending both cephalic and caudal from the defect. The technique involves lobes most distant from the primary defect being transposed in turn closer to the defect. The technique does not result in the unnecessary excision of Burrows triangle skin. The reducing opposed multilobed (ROM) flap reduces skin tension concerns, lowers the risk of flap necrosis and allows for quicker and more aesthetic healing.

After 20 cases, we have yet to experience dehiscence, infection or delayed healing. The healing wound is resistant to contraction and invariably produces an acceptable aesthetic outcome.

The ROM flap repair allows the dermatologic surgeon an additional option when faced with a medium sized lower leg defect following skin cancer excision.

 

Introduction:

Surgical defects on the low leg following excision of skin tumors are often problematic. The skin can be tight, especially anteriorly. Skin can be thin and of poor quality. Medical conditions such as peripheral vascular disease and diabetes can further compromise prospects of wound healing.

 

Traditionally small ( < 10mm ) defects on the low calf are closed by direct closure. Larger defects are traditionally closed by split skin graft. 186

 

There has been much attention to defects between 10 and 35 mm in diameter. To avoid the need for a split skin graft, a number of techniques have been popularized for these medium sized defects.

 

We describe a new random pattern flap technique for closing elective intermediate low leg skin defects. The reducing opposed multilobed flap (ROM Flap) addresses many of the shortfalls of previous skin closures of this size in this region. Replacing graft closure with a random-pattern flap repair enables the dermatologic surgeon to handle some low limb skin tumors in their own surgery that might otherwise require hospitalization.

 

Background:

Following excision of a skin tumor from the low calf, the elective defect remaining can be difficult to address. There is often minimal adjacent skin available for closure. Blood supply can be poor. The older populations that often suffer non melanoma skin cancer in this region are even more likely to have skin of poor quality and reduced perfusion.

 

Primary closure is limited on the lower leg to small defects. Even 10 mm diameter defects cannot always be closed directly. Skin tension can remain excessive and wound breakdown is relatively common. In addition, closing such defects with an ellipse means that skin at each of the tapered ends of the ellipse is “wasted”. That is, skin is removed beyond that required for adequate margin clearance of the tumor. In a patient with tight skin and considerable prospects of additional skin tumors elsewhere on the low leg, such skin wastage is not in the patient’s interests.

 

Random pattern flaps have been tried on the lower leg with limited success. Random pattern flaps can minimize skin “wastage”. However, skin tension can remain excessive for optimal healing. Excessive skin tension in closing a skin flap predisposes the flap to partial necrosis, usually to the extremity of the flap.

 

Furthermore, the length to base ratio of most random pattern flaps is such that perfusion to the tip of the flap becomes even more questionable. For example, a rhombic transposition flap has a length to base ratio of 1:1. The distal segment of this popular flap often lacks perfusion in usage on the lower leg, especially if the patient is elderly. A random pattern flap to the low leg needs to have a very favorable length to base ratio to ensure an acceptably low risk of end flap necrosis.

 

Other techniques for managing medium sized low leg defects include allowing the wound to heal by second intention. This approach has a role in some patients, but is invariably slow and involves considerable time with leg elevation. Furthermore, substantial nursing care and attention is required through the wound healing process. Others manage these types of defects with a purse string suture encompassing the entire defect. This often reduces the size of the defect to heal by second intention.

 

Surgical technique:

The diameter of the elective defect is measured. A mark is placed at the most cephalic aspect of the defect. From this point, a semicircle is drawn with a diameter 60 % of the diameter of the defect. A semicircle the same size is then drawn at the caudal end of the defect. The caudal semicircle must be orientated in the opposite direction to the cephalic semicircle. (See Figure 1)

 

Two more semicircles are drawn at the cephalic and caudal aspects of the original semicircles. These semicircles are 60 % of the diameter of the first semicircle. Additional semicircles are repeated, each being 60% the diameter of the preceding semicircle until the diameter of such semicircles measures 5 – 8 mm in diameter. (Figure 2)

 

Incisions are made along the semicircular surgical markings. The skin is then undermined in all directions. (Figure 3).

 

Starting at the extremities of the wound, the smallest semicircular flap is transposed into the adjacent larger semicircular defect. The suture is placed in keeping with the cross markers in Figure 1. The result is demonstrated in Figure 4.

 

The next semicircle flap is then transposed into its adjacent larger defect and sutured as indicated by the star markers in figure 1. Figure 5 demonstrates the closure at the completion of this stage. This process continues until the two largest semicircular flaps are transposed into the primary defect. (Figure 6).

 

This suturing process to this point may require deep anchor sutures at the locations identified in Figure 1. In our experience this is not often necessary. Skin hooks are helpful in positioning the lobes for deep and superficial suturing.

The semicircles transposed into the primary defects are then sutured in place as shown in Figures 6-8.

Additional sutures are then placed in the smaller transposed flaps to ensure wound edges are suitably approximated. (Figure 7 and 8). Figure 9 shows the completed repair. In this case the wound is on the antero-medial aspect of the right low leg and follows resection of an invasive squamous cell carcinoma.

 

Why 60%? We undertook modeling using a spring tension gauge on skin hooks. If the lobes were all reduced by 55%, the tension borne by the centre of the repair was significantly higher than the tension borne at the ends (peripheral tension).

 

With 70% reducing lobes, the peripheral tension was excessive compared with central tension. We attempted to find reducing lobes that enabled tension to be assumed evenly through the wound. Sixty percent produced even tension. Sixty-five percent reducing lobes produced slightly greater peripheral to central tension.

 

This crude modeling with the gauge on skin hooks was then applied to patients and their defects. In clinical application, the 60 % principle held up well. Some additional refinement of this model may produce further improvements in this technique.

 

We also tried models with variable percentage reductions. This increased the complexity of the overall repair without apparent improvement in the distribution of tension through the wound.

 

By way of comparison, primary elliptical closure, by its very nature, involves maximum wound tension centrally with very low wound tension peripherally. This places the centre of a tightly closed ellipse at considerable dehiscence risk.

 

The ROM flap can be applied to defects resulting from Mohs micrographic surgery or from defects based on a clinical margin of normal skin. We recommend that the specimen is marked to indicate its most cephalic point. We prefer use of a suture marker at this point. This allows easy correlation between the specimen and the wound should any revision be required. (Figure 9)

 

Post operative care:

Our patients are generally advised to restrict walking for two days to meet essential needs. From that point onward, we allow a gradual increase in walking capacity. We advise elevation of the leg when seated or lying. We do not require patients to spend lengthy periods with strict elevation. Most patients have returned to full duties by day 4, - except that we continue to ask them to elevate the leg when seated.

 

Figure 10 shows the same wound seven days following repair. Note that the semicircular incision loops have considerably lengthened and now appear as lines with waves either side of the wound centre. This effect is similar to a “Z” plasty effect. The wound is lengthened and subsequent contracture risk is reduced. The “Z” effect also allows tension in the healing to be assumed in multiple planes, reducing the risk of sudden tension in the plane perpendicular to the principle wound axis causing dehiscence.

 

All wounds have an occlusive dressing applied following surgery. We ask patients to leave this dressing intact for at least 4 days. We review the patient after one week and apply a further occlusive dressing. We review patients a week later for removal of sutures. Figure 11 shows the same wound eighteen days following repair. Healing is progressing. Figure 12 shows the wound one month after surgery.

Discussion:

A number of techniques have been tested to allow medium sized low leg defects to be closed satisfactorily without the need for a graft. Blair et al.187 describe how a long established technique involving opposing island pedicle advancement flaps can be applied to this clinical scenario. Delayed healing and wound infection still affected 15% of cases studied. Local subcutaneous flaps without an axial blood supply can produce poor perfusion compared with random pattern flaps. Penington et al86 describe a variation on this technique whereby a single “V”  - “Y” advancement flap is effected rather than two flaps. Delayed healing and partial flap necrosis remain issues with this technique.

 

The risk of partial flap necrosis can be reduced by shortening the distance of the random pattern of vasculature to the end of the flap. The ROM flap involves a very favorable length to base ratio of approximately 0.5:1. (Figure 13)

 

Complex axial flaps have proved successful in numerous lower leg deficits. 188, 189  These flaps involve mobilizing skin and deeper structures on a neurovascular pedicle. In particular, trauma that results in loss of much deep tissue as well as skin can be closed with good results using microvascular flaps, often based on the saphenous or sural systems. Most skin cancer deficits, however, on the lower leg involve only a skin defect along with subcutaneous tissue. Deeper structures are less commonly resected. With muscle planes and structures intact, disrupting same to close a skin defect is rarely appropriate.

 

Bilobed flaps were initially popularized for nasal defects following excision of non melanoma skin cancer. Indeed this technique has considerable advantages for nasal repairs. 150, 190 A bilobed flap allows excess skin around the bridge of the nose to be transposed through two lobes to a lower nasal defect.

 

Bilobed flaps have more recently been used as a means of closure for elective lower leg deficits. Bilobed flaps traditionally involve minimal if any reduction in lobe diameter as the flap is affected. As such, this technique can displace the wound tension when applied to the leg rather than spread the wound tension throughout the repair.

 

The bilobed concept and the axial flap concept have also been combined regarding large lower leg defects 191. This technique is perhaps more relevant to very large defects or defects involving much deeper structures than the medium sized defect resulting from skin cancer excision from the lower calf. “A” – “T” type and “O” – “Z” type flap repairs have also been used to close low leg defects.

 

Motley et al 192 describes an alternate method of adapting an established random pattern flap technique for usage on the lower leg. This involves meshing an advancement flap. This useful technique can result in the unsightly “fish scale” effect that follows skin meshing.

 

Cross leg flaps have also been used to close leg defects1 93. This results in prolonged incapacity and immobilization, and is suggested by the authors as being a consideration when considerable bone is exposed. This technique is not applicable to common leg defects following skin lesion excision from the leg.

 

Conclusion:

Although to date we have only performed this technique on twenty patients, we feel the reducing opposed multilobed flap repair offers another alternative when the dermatologic surgeon is faced with a medium sized defect on the low leg. To date, we have not experienced a patient suffering wound infection, flap necrosis or delayed or non-healing of their wound. Further, the dermatologic surgeon may be able to handle additional low leg cases in the surgery without the need for hospitalization.

 

Table 1 compares the theoretical benefits and disadvantages of the ROM flap with traditional primary closure and split skin graft for low leg defects. A larger trial is needed to compare the ROM flap closure with existing methods of closing medium sized low leg defects. The authors have commenced such a trial.

 

All figures have been deleted for this on line version of the manuscript.

 

Table 1. Comparison of ROM flap to traditional techniques for closure of low leg defects.

Feature

ROM Flap

Primary Closure

Split Skin Graft

Role closing elective medium defect size on low leg

Can often close with acceptable tension, avoiding graft

Closes small defects, medium defects close with considerable skin tension

Can be used even on very large defects

Difficulty of technique

Most difficult

Simplest technique

Intermediate

Donor site required

No

No

Yes

Elevation post op

1 – 4 days

2 – 5 days

Can be weeks

DVT risk through immobilization

Low

Low

High

Dehiscence risk closing medium sized defect

Low

High

Low

Cosmetic outcome

Good

Excellent if heals uneventfully, poor with breakdown or dehiscence

Poor, often depression at graft site, skin quality can be poor. Graft often has poor color and texture match

Return to normal duties

Quick

Slower

Slowest

Possible need for deep anchor sutures

Slight

High

No

Follows natural skin lines of tension

No

Yes

No

Post op care required

Average

Average

Heavy. Numerous dressings to both sites. Significant nursing care.

Wound length

Large for deficit

Shorter

Deficit length (& width)

Skin “wastage”

Ease of identifying site for revision of a margin

Minimal

Easy-if specimen oriented and marked

Can be considerable

Same

Minimal

Same

Wound tension in multiple planes

Semicircular incisions result in tension assumed in multiple planes

No, - All tension in a single plane

Graft assumes the negligible tension in wound

Coping with friction in post operative period

Small movement of negligible concern

Small movement of slight concern

Movement can interfere with graft taking

“Z” effect in repair to achieve wound lengthening and counter future wound contracture

Semicircular incisions lengthen wound in healing phase, - contracture risk greatly reduced

No lengthening possible, wound contraction can be disabling

Graft contracture risk