Avulsion Details

The word avulsion originates from the Latin word avellere. Avellere means "to tear off." The skin is what differentiates avulsion from other types of injury. The skin is completely ripped off in an avulsion, exposing the organs it's supposed to protect, such as muscle, bone, artery, even intestines. Avulsion typically occurs on the road, near a huge manufacturing machine, wild forest, and war zones.

The primary cause is an overwhelming physical force that completely displaces the skin and soft tissue, but not the bone. The source of overwhelming physical force could be vehicle momentum, operation of heavy machinery, strong animal bite, and gunshot impact. The second cause of avulsion is muscle overextension or displacement that results in muscle tissues expanding in the wrong direction, tearing the muscle from the bone and ripping the skin open. Response of avulsion injury can be categorized into three: repair/care, replantation, and amputation.

According to Kay, Werntz, and Wolff's Avulsion Injury Classification, doctors should perform repair/care treatment when the patient has light tissue damage indicated by partial tissue removal, but vessels, muscles, and bones are still largely intact. Doctors should perform replantation when the patient's vessel, nerve, and artery are fully exposed and potentially damaged, but the overall limb structure (including the bone) still largely intact. Doctors should perform complete amputation when the patient's nerves and veins are damaged beyond repair or completely stripped off any skin, muscle, vein, vessel, and nerve, leaving only the bone.

Avulsion Example

Ring avulsion is the most common avulsion injury. Let's examine an example of ring avulsion injury, including its primary cause, damage levels, and treatment types. Three primary main causes are: wearing a ring, working near heavy machinery, and lapses in concentration. Ring avulsion occurs when the ring of a victim is clamped, snagged, or stuck in a piece of machinery with moving contraptions, causing the machinery to pull, crush, or rip the ring with an extreme amount of force and take a part of the victim's finger.

Jack is an experienced machinist working in a big manufacturer. One day, he came to work late and sleepy because his newborn kept crying all night. Due to his sleepiness, the wedding band in his ring finger got caught inside the lathe machine and got forcefully pulled out, ripping off his entire ring finger skin and nails. Jack called for help and immediately got transported to the nearest hospital.

In the hospital, the doctor examined his avulsed ring finger and found four things:

  • Skin is completely ripped off
  • Muscles and tendons are exposed, slightly damaged from halfway to the tip of the finger.
  • Slight nerve and artery damage on the ring finger's very tip
  • Missing fingernail

The injury is classified as Urbaniak Class 1 injury, caused by 80 Newtons of traction force on the patient's ring finger. Blood circulation persists because the injured artery is located at the very tip. As a result, the doctors opted to do standard wound care by irrigating and sterilize the wound first, then addressing the missing skin issue. Because the ring finger skin is completely removed, the doctor performs a skin graft (replantation) operation using commercially available synthetic skin (acellular dermal matrix). Then, the doctor bandages the wound. After a few months, Jack's finger skin grows back normally, but the fingernail is still missing, only a thin sheet of keratin for now, and he can't feel anything on his ring fingertip (as a result of the nerve damage).

Avulsion vs. Hematoma

Hematoma/contusion/bruise is caused by bleeding of internal organs due to excessive physical impact. Physical impact ruptures the blood capillaries inside muscle tissues, tendons, or internal organs such as the brain and liver. The bleeding tissues could form a blood sac under the skin and cause the injured limb to be swollen. The injury also appears red or dark red due to internal bleeding visible from the skin.

The main difference between hematoma and avulsion is the skin. In hematoma, the skin is not torn, only softened, or suffered mild abrasion. The damaged tissues under the skin make the skin appear red. The skin is completely removed in an avulsion injury, exposing the soft underneath (that could also be damaged).

Hematoma injury is less severe than avulsion injury since doctors only need to make sure that the body heals itself without interruption. Meanwhile, patients often need a skin graft and extensive wound care due to exposed soft tissues, veins, and arteries in an avulsion injury. In some cases, avulsion could result in complete dismemberment of a limb, such as the patient's finger's last digit (finger bone). In this case, doctors could perform a replantation procedure to attach the finger back. However, this procedure is extremely difficult and risky.