RECONSTRUCTION AND SALVAGE OF DISTAL LIMB AND PAW WOUNDS Steven F

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RECONSTRUCTION AND SALVAGE OF DISTAL LIMB AND PAW WOUNDS

Steven F. Swaim, D.V.M., M.S.
Professor - Small Animal Surgery
Director - Would Healing/Reconstructive Surgery Program
Scott-Ritchey Research Center and
Dept. of Clinical Sciences
College of Veterinary Medicine
Auburn University, AL, U.S.A.

Three surgical techniques that the author is using to reconstruct and/or salvage traumatized distal limbs will be presented. These include adjustable horizontal mattress sutures, mesh skin grafts and paw pad grafts.

ADJUSTABLE HORIZONTAL MATTRESS SUTURE
Some wounds on the distal limb and paws may have some tissue missing. It may be possible to gradually stretch the surrounding skin to effectively close such wounds and thus avert the use of a skin graft by using an adjustable horizontal mattress suture. The technique should be used on wounds where there is not sufficient skin for initial wound closure. However, there is enough that it can be periodically stretched to gradually pull the skin over the wound. The suture can be placed early in wound management or after the formation of granulation tissue. Using monofilament nylon or polypropylene on a cutting needle, the suture is started at one end of the wound. The suture passes through the skin and is continued the length of the wound as a continuous intradermal horizontal mattress suture. The suture exits the opposite end of the wound. On each end of the wound, a sterile button is placed on the suture. At one end, removable split shot fishing weights are placed against the button. Traction is applied to the opposite end of the suture, the suture slides through the dermis, the wound edges move toward each other and then split shot are placed against the button to hold the skin under tension. The limb is bandaged for 24 hours. At that time, the suture is tightened by pulling on suture material that is beyond the original split shot. After the wound edges are pulled closer together, new split shot are applied near the button. The suture can be tightened at each end. The procedure gradually stretches the skin over the wound.

MESH SKIN GRAFTS
Large skin defects on the dorsum of the paw may be closed by mesh skin grafts. Either a bed of healthy granulation tissue or a clean surface vascular enough to produce granulation tissue is needed for grafting. Meshing a graft allows blood or exudate to drain from under the graft and allows placement of tacking sutures to immobilize the graft. This helps assure graft healing.
Epithelium is removed from the skin edge as needed and a sterile towel-pattern is made of the wound. The pattern is placed over the lower craniolateral thoracic area which has been prepared for surgery. Sterile methylene blue or a skin marking pen is used to trace around the pattern. A scalpel cuts the traced line, and scissors and thumb forceps are used to remove the graft. The donor site is closed using "walking" sutures, subcuticular sutures and skin sutures.
After the graft is fixed to a piece of sterile cardboard, all subcutaneous tissue is removed with scissors and thumb forceps. A number 11 scalpel blade is used to mesh the graft with staggered parallel rows of 1 cm long slits. The graft is placed on the wound and the edges are sutured/stapled to the wound edge. Simple interrupted sutures are placed between strategic mesh holes.
The grafted wound is bandaged with a nonadherent pad that has a thin coat of 0.1% gentamicin sulfate ointment (Garamycin®, Schering Corp.) on it. Absorbent wrap, a splint, and adhesive tape complete the bandage. Generally, the bandage is changed daily for the first postoperative week, every other day the second week, and twice the third week. If the dog molests the graft after bandage removal at week 3, one more week of bandage cover is used.

PAW PAD GRAFTS
Occasionally, paw trauma results in the loss of digital pads and the metacarpal/metatarsal pad. Animal owners may not accept limb amputation and insist on a salvage procedure which entails using pad grafts. After a healthy bed of granulation tissue forms, a mesh graft may be placed on nonweight-bearing tissue. Segmental pad grafts (6 x 8 mm to 1 cm2) can be placed in appropriately sized depressions cut in the granulation tissue on the distal end of the stump. After 5-0 nylon sutures are placed, bandaging is like a mesh graft. A "clam shell" splint is used to prevent the animal from bearing weight on the grafts as they heal. Lightening the bandage over time results in the grafts coalescing, maturing and hardening.
Paws from which grafts were taken are bandaged and the donor sites are bandaged with antibiotic ointment. The wounds are allowed to heal as open wounds.

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