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Permobil Blog / May 26, 2016

Wound Care: Understanding Shear

We are making progress in learning about the extrinsic factors that cause wound development. We tackled prolonged pressure but now we have to move onto a nasty thing called SHEAR.

Many people have heard the word however don’t fully understand the DEEP TISSUE DAMAGE resulting from shear, lacking the knowledge on what it really is and how to prevent it. Our unfamiliarity with shear can lead to a very serious wound that is difficult to detect until it is too late.


Shear is commonly misconceived to be friction. However, they are not synonymous. Friction is a part of shear but is not the only factor when discussing shear.

Shear is defined as:

  • A combination of downward pressure AND friction

  • It occurs at the deeper layers of tissue resulting in cell deformation and cell death

  • Shear is one of the major causes of skin breakdown in sitting and occurs during transfers, reaching, weight shifts or repositioning


Why is shear so dangerous?

It is so dangerous because it comes on without warning. I like to call it the “silent” extrinsic factor of wound development due to the fact that:

  • Wounds caused by shear usually go undetected since they occur in the deeper layers of our tissue. We are used to seeing a wound start superficially and only begin to take treatment steps once we see the reddening of the skin

  • However, a wound from shear, forms from the inside and expands outward to the surface of the skin

  • By the time the caregiver sees the wound, it is already at a very advanced stage

Here is a great diagram comparing pressure and shear.
It takes a closer look at what is happening beneath the skin at the cellular level:

Pressure and Shear

Another way to distinguish a wound caused by shear, is from its presentation. A wound caused by shear presents differently than a wound caused by pressure:

  • A wound caused by pressure is more symmetrical and usually is circular or oval in shape with even edges. It is usually under a bony prominence due to the peak pressures

  • A wound caused by shear on the other hand is asymmetrical, ragged and uneven in shape. It usually covers a greater surface area since it spreads as it grows upward and outward, initiating deep down and moving towards the superficial layer of the skin

Understanding shear is only half the battle. Knowledge on how to prevent it, provides you all tools necessary to fully fight against it. Next week, I will discuss caregiver tips on how to prevent shear and introduce you to an amazing product on the market that is specifically designed to fight shear and stop these “silent” wounds from occurring.


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Ana Endsjo-1

Ana Endsjo
Clinical Education Manager LTC Division

Ana Endsjo has worked as an occupational therapist since 2001 in a variety of treatment settings. She has mainly worked with the geriatric population, dedicated to the betterment of the treatment of the elderly in LTC centers. Her focus has been on seating and positioning and contracture management of the nursing home resident. With this experience, her hope is to guide other therapists, rehab directors, nurses, and administrators through educational guides, blogs, webinars, and live courses in her role as Clinical Education Manager for the long term care division.

Categories: Complex Rehab, Long Term Care, Seating and Positioning

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