Image Gallery: Surgical Tension Lines
Susanna Hinkle Schwartz, DVM, DACVS, MedVet Medical and Cancer Center for Pets, Cincinnati, Ohio
Leah Miller, DVM, MedVet Medical and Cancer Center for Pets, Cincinnati, Ohio
An awareness of skin tension lines is essential when excising masses or closing wounds. Failure to identify tension lines can result in incision dehiscence, skin necrosis, or even creation of a biological tourniquet on a limb.
Skin in different regions of the body has varying pliability, thickness, and attachments to underlying fascia. Age, concurrent metabolic disease, and breed type can affect skin characteristics. Tension in the skin is determined by the pull of collagen and elastin in the dermal and hypodermal layers. Maps of Langer lines that can help novice surgeons determine accurate lines of tension are described in the literature (see Suggested Reading).
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In general, closure of the wound parallel to tension lines is the easiest technique. Parallel closure results in less tension on sutures and fewer dog ears (ie, unsightly skin puckering), while avoiding damage to underlying vasculature on a limb. In attempts to close an incision or wound, the skin edges should be gently manipulated in several directions to ensure the closure does not exceed tension limits. Closure should be continued only if the skin can bear minimal tension. Placement of towel clamps or skin hooks can be useful in determining where tension is the greatest, in addition to holding the skin in apposition to facilitate suturing. When the incision is subjected to too much tension, tension-relieving techniques should be considered. The simplest technique is undermining the tissue underneath the panniculus (where present) while avoiding the vascular supply. Other techniques include:
Tension-relieving suture patterns
Vertical mattress
Far-near-near-far
Horizontal mattress through rubber stents
Releasing incisions
Z-plasty or V-Y plasty
Stretching techniques.
Figure 1 A 2-cm mass showing 2-cm margins as drawn
An elliptical incision drawn around the margins to result in aesthetic closure. The owner should always be warned about the length (and appearance) of the incision in relation to the size of the mass. The rules of an elliptical incision are also applicable to circular wounds.