How to Use Delayed Closure for Limb Wound Management

1. Introduction

Veterinarians have several options for management of traumatic limb wounds in horses.^1,2  Primary closure describes wound closure with sutures within a few hours of injury. Healing in such cases, termed primary (first intention) wound healing, provides optimal cosmetic and functional outcome as well as the most rapid return to work. A wound that is left open (i.e., not closed with sutures) heals by a combination of wound contraction and epithelization known as secondary (second intention) healing. Contraction is modest in limb wounds that have lost skin, hence the predominant method of closure in such wounds is by migration of epithelial cells from the wound margins. This is a notoriously slow process, ultimately resulting in an unaesthetic hairless scar of poor mechanical durability. Delayed closure, a third option for management of traumatic limb wounds, may be highly effective in selected cases.^1–3  In this technique, the wound is originally left open, normally to reduce the risk of infection, and then closed at a later date. If the wound is closed before granulation tissue is visibly evident (normally 4–5 days), the procedure is termed “delayed primary closure,” and the outcome is considered primary healing (the same healing as occurs in a wound sutured primarily).⁴  If closed after granulation tissue is evident, the procedure is secondary closure and results in tertiary (third intention) healing. 

Delayed closure of limb wounds is indicated in traumatic wounds that have had little or no loss of tissue but, for some reason, were not sutured primarily.^1-3 Failure to close a wound primarily may be elected if a wound is seen shortly after injury but is considered to be highly contaminated with bacteria and foreign material and/or has severe local trauma, resulting in impaired local tissue defenses. Closure of such wounds primarily leads to a high risk of wound infection and dehiscence. If such wounds are left open for a few days before closure, the risk of infection is dramatically reduced with an outcome still considered primary wound healing. There is no substantial fibroplasia in a wound before 4 to 5 days after injury, so closure anytime before this point has minimal effect on gain of tensile strength. In other cases, failure to present the case until considerable time has elapsed allows substantial tissue edema and bacterial colonization of tissues, eliminating primary closure as a treatment option. These wounds have missed the “window” for primary closure but may be still be good candidates for delayed primary closure. Secondary closure (after granulation tissue has formed in the wound) is an option for older wounds that were not sutured earlier or underwent dehiscence after primary closure. Delayed closure techniques can be used on wounds of the upper limbs or trunk, but these areas normally contract so well that this is unnecessary.

This report describes use of delayed closure techniques for limb wounds in horses.
 

2. Materials and Methods

Fresh wounds are candidates for delayed closure if there is little or no tissue loss, but there is a high risk of wound infection and dehiscence with primary closure. In such cases, wound preparation mirrors that used in wounds undergoing primary closure. The procedure is normally done with the horse standing under appropriate sedation and wound anesthesia (regional block or local infiltration). The skin around the wound is clipped and surgically prepped. The wound bed is ideally prepared by complete wound excision (en bloc debridement), the sharp removal of superficial tissues covering the entire surface of the wound (Figs. 1 and 2). This is the most effective technique for removing bacteria and particulate foreign material from the wound and for eliminating severely damaged tissues. Less aggressive (simple) debridement will be required in areas of wounds when vital structures such as tendons, nerves, or major vessels are exposed. In this case, grossly visible foreign material and devitalized tissues are removed. The wound should be copiously lavaged, using balanced electrolyte solution at a low pressure (gravity flow, syringe spray, squeeze bottle). High-pressure lavage such as that delivered by a pulsatile unit should be avoided because it may waterlog tissues. Dry gauze sponges are placed over the wound, and a pressure wrap is applied. The bandage is changed every 1 to 2 days, and the wound is gently cleansed by wiping with dry gauze sponges and sharp debridement as needed. Concurrent therapy includes regional limb perfusion with antibiotics (in cases with severe trauma or contamination or involving synovial spaces), systemic antibiotics, nonsteroidal anti-inflammatory agents, and tetanus prophylaxis. [...]