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Specific Lacerations
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General considerations

The injury: The mechanism of injury is important in assessing the degree of risk of complications of a given wound. For example, the farmer who pierces his foot with a manure-laden pitchfork is at high risk for gas gangrene and sepsis. Management would include extensive local wound care and possible admission to hospital for intravenous antibiotics. Mammalian bites present another risk situation for infection. Is there likely to be a foreign body present in the wound? Does the force of injury suggest there is likely to be extensive trauma to deeper tissues?

The patient: Consider complicating medical conditions such as diabetes, other immunosuppressed states including diabetes or other major organ dysfunction (such as renal or hepatic failure) and peripheral vascular disease. These all may affect both resistance to infection and wound healing itself.

Time of injury: The age of the wound is important in deciding the timing of closure, if at all.

Laceration
Age / Condition
Treatment
Extremity
< 12 hours and “clean”
suture primarily
Extremity
>12 hours older or “dirty”
Older or obviously contaminated or infected lacerations are best left alone for healing by secondary intention or tertiary intention (closure a few days later). Saline soaks and antibiotics usually will be required. If cosmetic or other functional considerations apply, then referral to a plastic surgeon is necessary.
Face
< 24 hours
suture primarily unless obviously infected (rare)


These times are based on common medical practice in Canada. A study of forearm and hand lacerations found that closure within 4 hours had a lower infection rate than more than 6 hours from injury.1

Consultation: Emergency physicians may consider early referral of certain lacerations to an appropriate surgeon. Indications for referral could include:

  • Deep lacerations that involve nerve, tendon (often flexor tendon injuries of the fingers) or bone,
  • Complex or extensive lacerations that may be challenging to repair or are located in difficult anatomical areas.



Assessment of function and the importance of wound exploration

Assess wounds under optimal lighting with minimal bleeding. Important structures underlying any laceration or contusion should be assumed divided until proven otherwise. Motor, sensory and vascular function must always be assessed.

The physician, however, cannot rely only on tests of motor or sensory function to rule out injuries to tendon or nerve. Only a small portion of a tendon in the finger, for example, needs to remain intact to maintain function. However, if the patient is sent home with such a partial tendon injury, total rupture may occur when the tendon is stressed.

Note that there is no reliable test for isolating a particular wrist flexor or extensor, because more than one muscle performs the same function.

Therefore, wounds in the vicinity of important structures should be gently explored. If visualisation is difficult or the anatomy complex, then an appropriate surgeon should be consulted.

Tendon, nerve or vascular injuries are all too easy to miss unless due care is taken.

Finger Injuries

Injuries to the fingers and hands account for the majority of such cases. Tendon and nerve injuries of the fingers will now be reviewed, followed by a brief discussion of vascular injuries.

Tendon, nerve or vascular injuries are all too easy to miss unless due care is taken. In addition for testing function, these wounds should be gently explored. Injuries to the fingers and hands account for the majority of such cases.

A tendon is visualized through the open wound margin of this wound of the hand.

Finger Injuries

Tendon and nerve injuries of the fingers will now be reviewed, followed by a brief discussion of vascular injuries.

  1. Extensor Tendon Injuries of Fingers: The anatomy of the extensor aponeurosis is depicted in the diagram below. Extension is accomplished through the action of the extrinsic digital extensors, and the interosseous and lumbrical muscles.

    Transection or avulsion of the central extensor slip from the base of the middle phalanx may allow the lateral band to slip in a volar direction and assume a PIP flexor action. This produces the classical “boutonniere deformity”. The patient may initially exhibit a full range of motion, including extension.



 

  1. Flexor tendon injuries of fingers: A missed flexor injury of the finger may result in long term disability. The anatomy is depicted in the accompanying diagram. The profundus runs the entire length of the finger and inserts into the distal phalanx. If intact, the finger can move normally, even if the superficialis is divided.

    Profundus tendon testing of
    long finger D3
    Superficialis tendon testing of
    long finger D3

    The testing of these tendons – both the profundus and the superficialis is shown
    above. The test of the superfialis tendon can only be accomplished with all of the other digits being restrained in extension. Moreover, it is not reliable for the index finger. These tests do NOT replace exploration and visualization of the tendons in the wound.



 

  1. Digital nerve injuries: The digital nerves exit the hand in the region of the volar web spaces, tracking along the medial or lateral aspects of the fingers.

    The digital nerves run immediately adjacent to the flexor tendons.

    Numbness or complete loss of feeling is not necessarily noted by the patient immediately even if there is complete transection of the nerve. A peculiar or unusual sensation in the territory of the nerve may be the only subjective description.

    If there is digital arterial bleeding, then the digital nerve is likely to be injured.

    Sensory testing is best done using two-point discrimination.

    If the history or physical findings suggest the possibility of a digital nerve injury, then exploration to visualise the digital nerve is necessary. A referral to a plastic surgeon is necessary. However, digital nerve injuries beyond the level of the DIP joint are not repaired and do not require referral.





 

  1. Vascular Injuries
    Most arterial and venous injuries occur within the traumatised limbs. Early diagnosis is important.

    Consider the proximity of the wound to arterial structures. A history of bright red blood spurting from a wound indicates an arterial injury. Often, by the time of evaluation within the Emergency Department, this bleeding has stopped because of vasospasm (or uncommonly because of hypovolemic shock).

    The presence of a bruit or thrill frequently indicates a significant vascular lesion. Look for the classic six “P’s” in the distal extremity:

    pain
    pallor
    pulselessness
    paresthesia
    paresis
    poikilothermia

    Pulses may or may not be absent depending on the degree of injury.

    Venous injuries that are significant may be difficult to diagnose. These usually co-exist with arterial or nerve injuries. Arteriovenous fistula may occur.

    Compartment syndrome:
    Look out for
    1. Passive stretch pain of the muscles within the compartment
    2. Compartment swelling

The involved compartment needs to be released immediately.



 
©2003 Department of Emergency Medicine, University of Ottawa

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