Types and Causes of Blunt Force Trauma
Blunt force trauma happens when a part of the body strikes, or is struck by, a blunt object. Generally speaking, blunt objects that cause injury have much greater surface area relative to sharp objects that cause injury. With sharp-force trauma (detailed blog post is in the works) the cutting edge only needs a small surface area to cause injury. Common objects causing blunt force trauma include vehicles, fists, sidewalks, roads, baseball bats, and hammers. Common blunt-force injuries include abrasions, avulsions, contusions, & lacerations.
Abrasions occur when a part of the body scrapes across another surface, generating enough friction to disrupt skin integrity. Sometimes the skin and the surface causing the abrasion come into contact briefly (think of the accidentally scraping your upper arm against a brick wall, or falling onto your outstretched hand) and other times the contact with the surface can be prolonged (such as that of a body being dragged underneath a car and scraping against the road).
Abrasions can happen due to the skin having contact with either a hard or a soft surface, although obviously more force would be needed to cause an abrasion with a soft surface. The examples above describe the contact of skin with a hard surface. An example of a soft surface causing an abrasion would be ligature marks on the wrists of someone restrained with a shoelace.
The direction in which the force was applied can be determined by which part of the wound margin demonstrates more skin “beading.” The last part of the wound to have contact with the offending surface will show more skin beading that the rest. In the photo, the skin beading visible on the left-most aspect of the wound margin (red arrow) indicates that the direction of force likely followed the direction of the black arrows. Beaded skin sloughs off soon after injury so early photos of injuries are key.
Matter embedded in an abrasion or laceration can also help determine mechanism of injury. For example tiny, cube-shaped fragments of glass in an abrasion following a motor vehicle accident indicate the glass was from a side-window (made of tempered glass) rather than a windshield (made of laminated glass, which shatters into longer, flatter shards). This can help determine an individual is being truthful about their position in the vehicle during a motor vehicle accident case.
Images below this box show wounds, which may be disturbing to some readers.
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If a fracture is a split in a bone an avulsion is its counterpart in soft tissue (the are also types of bone fractures called avulsion fractures, but we won’t get into that now). Avulsions are splits in the soft tissue, which can occur with or without lacerations to the skin. They are typically due to shearing forces. Shear isn’t just friction but the combination of friction with pressure resulting in tissue being forcefully torn away from where is supposed to be. They range from simple skin tears in the elderly (PHOTO) to traumatic avulsions involving subcutaneous tissue and even underlying muscle and bone (not shown). Pattens of injury with avulsions can also help establish directionality.
Both abrasions and avulsions can happen before or after death. Abrasions caused prior to death are usually brown or red due to subsequent blood flow to the area. Post mortem abrasions are usually yellow. However, this is not always the case in lividity-dependent areas (area where blood pools within the body post-mortem).
Contusions are bruises caused when the soft tissue and blood vessels under the skin are torn and cause bleeding beneath the skin. True contusions & hematomas only occur while the victim is living, however if the victim is dead lividity in dependent areas can make things hard to distinguish. Contusions and hematomas are generally distinguished by severity but there is overlap. Simple contusions are caused by the breaking of smaller blood vessels releasing blood diffusely into the skin whereas a hematoma is a pooling of blood outside of a blood vessel (in skin, subcutaneous tissue, body cavities).
There is a tendency to want to “date” bruises by their coloring and if there are multiple bruises in various stages of healing its reasonable to assume that some are older in comparison to others, but to accurately date injured tissue histopathology is necessary. This would involve microscopic examination of the injured tissue. Contusions and hematomas can appear differently based on many factors including skin color. They can also change in appearance after death.
Many people associate lacerations with sharp-force injuries. Health care providers even sometimes describe injuries caused by sharp objects as lacerations but in reality there are differences in appearance between lacerations and injuries caused by sharp objects. Lacerations can be caused by blows to the skin, stretching of the skin, and crushing of the skin. Lacerations have irregular margins and usually there are pieces of tissue or blood vessels within the wound that are still connected.
If your case requires you to demonstrate whether or not an injury could have been caused by a certain object or you need medical research to support your case, reach out to us today for a cogent medical opinion from a Legal Nurse Consultant.
Want to learn how to identify problems and deficiencies with your case's medical records? Check out these posts:
Missing and Altered Medical Records: the Value of a Clinical Eye on Deficiencies in Medical Records
Why Do Parts of the Medical Record "Go Missing"?
What's an Attorney to do Regarding Missing Medical Records?
What's an Attorney to do When Confronted with the Possibility of Altered Medical Records?
I'm Jennifer Pettigrew and, true story, I first became interested in Legal Nurse Consulting after my auto insurance company was sued following a car accident in which I was found to be at fault. I wasn't sued until after the statute of limitations was up but an exception was made and the plaintiff alleged that because of being rear-ended he was on pain medications chronically which caused him to develop diabetes and become blind. As a nurse I knew that Diabetic retinopathy cannot develop over the course of just a few years but rather is a complication that develops after several years of untreated or poorly treated diabetes. The case was settled by the insurance company before ever going to court for several million dollars, but from that point on I have been interested in the difference medical professionals could make in legal proceedings.