Chapter 13. Lacerations to the Leg and Foot

The mechanism of the injury determines the likelihood of disruption to underlying tissue, the risk of a retained foreign body, and the degree of potential contamination. The following circumstances are associated with specific pathogens: (a) farming accidents (Clostridium perfringens), (b) wading in a freshwater stream (Aeromonas hydrophila), and (c) high-pressure water systems used for cleaning surfaces (Acinetobacter calcoaceticus). Evaluation of wounds in general is discussed in Chapter 9. It is important to determine the position of the limb at the time of injury, which will help to uncover occult tendon injuries.

Assessment for associated nerve, vessel, or tendon injury is mandatory. Before anesthetizing the area, inspect the wound for position at rest, and assess sensory neurologic function using light touch and 2-point discrimination testing. Compare one side with the other. Motor function and wound exploration may be better assessed after the wound is anesthetized (Tables 13-1 and 13-2). Move the limb through its full range of motion to exclude tendon injury. Test each tendon function individually and inspect visually to rule out a partial laceration.

Laboratory studies usually are not indicated. Obtain an x-ray if there is a possibility of fracture or a radiopaque foreign body. Ultrasonography may be used to help identify a foreign body, a tendon injury, or bony abnormality. All injuries caused by glass should be radiographed unless physical examination can reliably exclude a foreign body (see Chapter 14).

General Recommendations

1. See Chapter 9 for discussion of wound preparation; thorough irrigation of lower extremity wounds is essential.

2. Wounds on the lower extremities are usually under greater tension than those on the upper limb. Consequently, a layered closure with 4-0 absorbable material to the fascia and interrupted 4-0 nonabsorbable sutures to the skin are preferred. The foot is an exception to this guideline.

3. Avoid deep sutures in diabetics and patients with stasis changes because of the increased risk of infection.

4. Always ask about tetanus immunization status. The elderly are at particular risk for being nonimmunized.

5. Cyanoacrylate glue is usually not used on the lower extremities because of greater wound tension.

6. Splint lacerations involving the joint or tendons in a position of function.

Knee Injuries

1. Examine knee wounds throughout the range of movement.

2. Evaluate the joint for possible penetration of the joint capsule and laceration of the patellar and quadriceps tendons. An x-ray may show air in the joint.

3. An alternative approach to diagnose joint penetration is to inject 60 mL of sterile saline, with or without a few drops of sterile fluorescein, into the joint by using a standard joint aspiration technique at a site separate from the laceration. Leakage of the solution from the wound indicates joint capsule injury.

4. The popliteal artery, the popliteal nerve, and the tibial nerve are at risk around the knee: always ascertain their integrity.

5. After closure, splint the knee to prevent excessive tension on the wound edges.

Ankle Injuries

1. Move the ankle through its full range of motion and directly inspect the wound to ensure there are no tendon injuries. Particularly at risk are the Achilles tendon, the tibialis anterior, and the extensor hallucis longus.

2. If any of these tendons are injured, they should be formally repaired.

3. The Achilles tendon can rupture without a penetrating injury when a tensed gastrocnemius is suddenly contracted. The Thompson test can be used to assess the Achilles tendon. While kneeling on a chair, or while the patient is supine with feet extending beyond the stretcher (see Fig. 13-1), the patient's calf is gently squeezed at the midpoint. Absent plantar flexion of the foot indicates complete Achilles tendon laceration (a partial injury may yield plantar flexion).

Foot Injures

1. Explore lacerations of the sole of the foot to ensure the absence of tendon injury and the absence of foreign bodies. Place the patient in a prone position, with the foot supported on a pillow or overhanging the bed.

2. Regional anesthesia is often best for exploration and repair of lacerations in this area.

3. Some wounds older than 6 hours and less than 12 hours at presentation can be repaired primarily. Each wound must be evaluated individually.

4. Large needles are required to penetrate the thick dermis of the sole. Use nonabsorbable 3-0 or 4-0 material for the sole and 4-0 or 5-0 nonabsorbable sutures for the dorsum.

5. Lacerations between the toes can be difficult to repair. The presence of an assistant who holds the toes apart can be a great help. An interrupted mattress suture often is required to ensure adequate skin apposition.

6. Crutches and a walking boot may be required after repair of any laceration on the foot.

7. Lawn mowers and bicycle spokes may cause extensive soft tissue injury, in addition to underlying fractures and tendon lacerations. These severe injuries require the services of an orthopedic specialist.

8. Consider antibiotic prophylaxis for patients at risk by history or injury mechanism.

9. Wounds caused while wading in fresh water are prone to infection with Aeromonas. Prescribe a fluoroquinolone such as ciprofloxacin 500 milligrams bid. In children, use trimethoprim/sulfamethoxazole, 5 mL suspension per 10 kilograms up to 20 mL bid. Aeromonas should be considered in any rapidly progressive case of cellulitis in the foot after an injury.

Hair Tourniquet Syndrome

1. Hair tourniquet syndrome is an unusual type of injury seen in infants. A strand or strands of hair wrap around one of the toes, producing vascular compromise.

2. The hair must be completely cut to avoid compromising the neurovascular bundle to the toe.

3. This is best accomplished by making an incision perpendicular to the hair on the extensor surface of the toe down to the extensor ligament.

1. Instruct patients to keep wounds clean and dry.

2. Remove sutures in 10 to 14 days for the lower limb and in 14 days for lacerations over joints.

3. Provide routine wound care instructions. Elevation of the affected limb will reduce edema and aid healing.

4. Recheck wounds after 48 hours if they were heavily contaminated or if a complex repair was required.

5. Crutches can be used for 7 to 10 days, as needed, to prevent additional tension on the wound.