# Wound Management: Lacerations, Bite Wounds, and Closure Techniques

## Introduction

Wound management is among the most common tasks in emergency medicine, accounting for approximately 12 million ED visits annually in the United States. Proper technique in wound evaluation, irrigation, closure, and aftercare directly impacts cosmetic outcomes, infection rates, and patient satisfaction. This lecture covers laceration repair, bite wound management, and the spectrum of closure techniques.

## Initial Assessment

The history should establish the mechanism of injury, time since injury, tetanus immunization status, allergies (especially to local anesthetics and latex), medications (anticoagulants, immunosuppressants), and relevant comorbidities (diabetes, peripheral vascular disease, immunocompromise). Wound examination determines the location, depth, length, degree of contamination, and involvement of underlying structures including tendons, nerves, vessels, joints, and bone. A neurovascular assessment should test two-point discrimination (normal is less than 5 mm on fingertips), capillary refill, and motor function distal to the wound before anesthesia is administered. Tendon evaluation requires examining active range of motion against resistance, recognizing that partial tendon lacerations may preserve full range of motion but produce pain with resistance. Foreign body assessment involves direct wound exploration, with plain radiographs obtained when glass, metal, or gravel contamination is suspected.

## Anesthesia

Topical anesthesia with LET gel (lidocaine 4 percent, epinephrine 0.1 percent, tetracaine 0.5 percent) is first-line for pediatric facial and scalp lacerations and should be applied for 20 to 30 minutes. Local infiltration with 1 percent lidocaine (maximum dose 4.5 mg/kg) or 1 percent lidocaine with epinephrine (maximum dose 7 mg/kg) is the standard for most wounds. Buffering lidocaine with sodium bicarbonate in a 9:1 ratio significantly reduces injection pain. Digital nerve blocks are used for finger and toe lacerations; while lidocaine without epinephrine was the traditional teaching, modern evidence supports the safe use of epinephrine in digital blocks. Regional nerve blocks, including infraorbital, supraorbital, mental, and auricular blocks, reduce the total volume of anesthetic needed for facial wounds.

## Wound Preparation

Irrigation is the single most important step in reducing wound infection. Normal saline or tap water (which has equivalent infection rates in multiple randomized controlled trials) is delivered at a pressure of 5 to 8 psi, achieved with a 30 to 60 mL syringe and an 18-gauge angiocatheter. For contaminated wounds, at least 200 mL per centimeter of wound length should be used. Devitalized tissue and wound edges should be debrided with sharp excision to create clean, well-perfused margins. Hair should be clipped rather than shaved, as shaving increases infection rates. Eyebrow hair should never be removed because it may not regrow correctly. Antiseptics such as chlorhexidine or povidone-iodine are used for perilesional skin preparation but should not be irrigated directly into the wound, as they are cytotoxic to fibroblasts.

<image>Wound irrigation technique showing a clinician using a 60 mL syringe attached to an 18-gauge angiocatheter delivering high-pressure normal saline irrigation to a laceration on the forearm, with a splash guard in place</image>

## Closure Techniques

### Primary Closure (Sutures)

Simple interrupted sutures are the most versatile technique, allowing precise wound edge alignment and serving as the standard for most ED lacerations. Horizontal mattress sutures evert wound edges in areas of skin tension and are useful for thin skin on the extremities. Vertical mattress sutures provide both deep and superficial closure in a single suture, achieving excellent wound edge eversion. Deep (dermal) sutures use absorbable material placed in the dermis to reduce dead space and wound tension before skin closure. Running sutures provide faster closure with even distribution of tension and are ideal for long linear lacerations with well-aligned edges. Corner (half-buried mattress) sutures preserve blood supply to flap tips by entering the dermis of the flap without penetrating the surface.

### Suture Material Selection

Non-absorbable sutures such as nylon (Ethilon) or polypropylene (Prolene) are used for skin closure and produce minimal tissue reactivity. Absorbable sutures including polyglactin (Vicryl) or poliglecaprone (Monocryl) are used for deep and dermal sutures. Vicryl Rapide or fast-absorbing gut is useful for pediatric facial repairs because no removal is needed. Suture size is selected based on location: 6-0 for the face, 4-0 or 5-0 for extremities and trunk, and 3-0 or 4-0 for the scalp.

### Tissue Adhesives

2-octyl cyanoacrylate (Dermabond) produces equivalent cosmetic outcomes to sutures for simple, low-tension lacerations. It is applied in 3 to 4 layers while holding the wound edges together for 30 to 60 seconds. It should not be used on the hands, over joints, on mucosal surfaces, or in high-tension areas, and ointment or moisture should not be applied over the adhesive.

### Staples

Staples are the fastest closure method and are ideal for scalp lacerations and long linear wounds on the trunk or extremities. They produce equivalent infection and cosmetic outcomes to sutures on the scalp but are not appropriate for the face, hands, or feet.

### Hair Apposition Technique

For scalp lacerations, hair from opposite wound edges can be twisted together and secured with tissue adhesive. This technique avoids the need for anesthesia, instruments, or follow-up for removal.

<image>Comparison illustration showing five suture techniques side by side: simple interrupted, horizontal mattress, vertical mattress, deep dermal, and corner (half-buried mattress) sutures, each with cross-sectional diagrams showing needle path through tissue layers</image>

## Bite Wounds

### Dog Bites

Dog bites are the most common mammalian bite. Pasteurella canis is the predominant organism, along with Staphylococcus, Streptococcus, and anaerobes. Copious irrigation is essential. Primary closure is acceptable for most facial dog bites because the cosmetic benefit outweighs the infection risk. Prophylactic antibiotics with amoxicillin-clavulanate 875/125 mg twice daily for 3 to 5 days are indicated for hand bites, deep puncture wounds, crush injuries, immunocompromised patients, and wounds near joints or prostheses.

### Cat Bites

Cat bites produce deep puncture wounds with a high infection rate of 30 to 50 percent because the needle-like teeth inoculate bacteria deep into tissues. Pasteurella multocida is the most common pathogen, and rapid-onset cellulitis within 12 to 24 hours is characteristic. All cat bites warrant prophylactic antibiotics, and puncture wounds should not be closed primarily.

### Human Bites

Clenched-fist injuries ("fight bites") over the MCP joints are surgical emergencies if the joint capsule is violated. The key pathogens include Eikenella corrodens, Staphylococcus, Streptococcus, and oral anaerobes. Hand X-rays should be obtained to evaluate for fracture, foreign body, and joint involvement. Prophylactic antibiotics with amoxicillin-clavulanate are indicated, and hand surgery should be consulted for fight bites with joint involvement.

## Tetanus and Rabies Prophylaxis

Tetanus prophylaxis with Tdap is indicated if the last vaccination was more than 5 years ago for contaminated wounds or more than 10 years for clean minor wounds. Tetanus immune globulin (TIG) should be added if the patient has received fewer than 3 prior vaccinations. Rabies post-exposure prophylaxis should be considered for bites from bats, raccoons, skunks, foxes, and unvaccinated dogs or cats, with rabies immune globulin infiltrated around the wound and a rabies vaccine series initiated.

<image>Clinical photograph-style illustration comparing dog bite laceration on the forearm, cat bite puncture wound on the hand with surrounding erythema, and a clenched-fist injury over the MCP joint with annotation of the underlying extensor tendon and joint capsule</image>

## Suture Removal Timing

| Location | Removal Time | Notes |
|----------|-------------|-------|
| Face | 3–5 days | Replace with adhesive strips |
| Scalp | 7–10 days | Staples also acceptable |
| Trunk | 7–10 days | — |
| Extremities | 10–14 days | — |
| Over joints | 14 days | Immobilize during healing |

Sutures on the face should be removed at 3 to 5 days (replacing with adhesive strips), on the scalp at 7 to 10 days, on the trunk at 7 to 10 days, on the extremities at 10 to 14 days, and over joints at 14 days.

## Clinical Pearls

High-pressure irrigation is the most effective single intervention to reduce wound infection rates. Wounds older than 12 to 18 hours on the body (or 24 hours on the face) can still often be closed primarily if adequately irrigated and debrided. Cat bite puncture wounds should never be closed primarily because of their high infection rate. Cosmetic outcome on the face depends more on wound edge eversion and atraumatic technique than on the choice of suture material. Neurovascular status and tendon function should always be documented before administering anesthesia.

## References

1. Hollander JE, Singer AJ. Laceration management. *Ann Emerg Med*. 1999;34(3):356-367.
2. Dire DJ, Hogan DE, Walker JS. Prophylactic oral antibiotics for low-risk dog bite wounds. *Pediatr Emerg Care*. 1992;8(4):194-199.
3. Quinn JV, Drzewiecki A, Li MM, et al. A randomized, controlled trial comparing a tissue adhesive with suturing in the repair of pediatric facial lacerations. *Ann Emerg Med*. 1993;22(7):1130-1135.
4. Medeiros I, Saconato H. Antibiotic prophylaxis for mammalian bites. *Cochrane Database Syst Rev*. 2001;(2):CD001738.