When a pressure injury fails to improve after weeks or even months of treatment, it is often labeled a non-healing wound. Certainly, many factors can prevent a wound from healing, including poor circulation, diabetes, malnutrition, infection, medications, advanced age, improper dressing use, and underlying medical conditions, and these should always be evaluated as part of a comprehensive wound assessment. But there is another question worth asking: what if the wound is actually healing, only to be repeatedly damaged before the healing process can be completed? Understanding this possibility may change how clinicians, caregivers, and individuals evaluate both the patient and the support surface beneath them.

The Invisible Tug-of-War: How Wounds Try to Heal and Get Damaged Again

Pressure injury healing is not simply a matter of applying dressings and waiting for tissue to close. The body is constantly trying to repair damaged tissue by creating new blood vessels, producing collagen, and forming delicate granulation tissue, while mechanical forces continue acting on the wound every minute the individual remains in bed or seated. Healing can be thought of as a balance:

• When tissue repair exceeds ongoing damage, the wound progresses toward closure.
• When repair and damage occur at roughly the same rate, the wound appears stalled.
• When damage exceeds repair, the wound deteriorates.

A wound that appears "non-healing" may actually be caught in this mechanical tug-of-war.

What Is Pressure Redistribution, and Why Does the Right Mattress Matter?

One of the primary goals of a therapeutic support surface is to reduce prolonged mechanical forces such as pressure. Sustained pressure compresses tiny blood vessels, limiting oxygen and nutrient delivery to tissue; without adequate blood flow, cells become deprived of oxygen, waste products accumulate, and tissue begins to break down.^[7]

Alternating pressure mattresses are designed to interrupt this cycle by periodically redistributing pressure across different areas of the body, allowing blood flow to return and reducing prolonged tissue compression and cellular deformation. It is worth noting that clinical trial evidence comparing alternating pressure surfaces to other advanced static surfaces, such as high-specification foam, has been mixed, and no single surface type is clearly superior for every individual.^[4][5] For many individuals, pressure redistribution alone may be enough to support healing, but pressure is only part of the mechanical equation.

The Hidden Danger of Shear: How Sliding in Bed Tears Fragile Skin

Pressure injuries rarely develop from pressure alone. As individuals slide down in bed, are repositioned, transferred, or spend extended periods with the head of the bed elevated, tissues are exposed to shear forces. Unlike pressure, which acts perpendicular to the skin, shear causes layers of tissue to move in opposite directions: the skin may stay relatively stationary against the mattress while deeper muscle and tissue shift beneath it.

Two types of shear are relevant here: shear between the body and the support surface, and shear between the skeleton and the layers of muscle, fat, and connective tissue that lie above it, which is the mechanism behind deep tissue injury (DTI).^[1] This stretching and distortion can damage small blood vessels, increase tissue deformation, and place significant stress on fragile healing tissue, often while the wound looks unchanged on the surface.^[2]

Is the Pressure Wound Stuck in a Reinjury Cycle?

A healing pressure injury develops fragile new capillaries, collagen fibers, and granulation tissue, and during the early stages of repair this tissue is extremely vulnerable.^[6] If excessive pressure, tissue deformation, or shear continues, portions of this newly formed tissue may be damaged before they mature. The body responds by restarting the repair process, only for another episode of mechanical stress to cause another small setback. The cycle repeats.

Rather than labeling the wound "non-healing," it may be more accurate to describe it as repeatedly healing and being mechanically reinjured: the individual is making progress, but that progress is continually interrupted. Over time, a wound repeatedly reinjured this way can become stuck rather than ever advancing to closure.^[6]

Why Changing the Support Surface Is a Critical Step

A therapeutic support surface should help create an environment that minimizes the mechanical forces acting on vulnerable tissue.^[3] Important questions to ask include whether the surface effectively redistributes pressure, allows adequate immersion and envelopment, reduces tissue deformation, helps minimize the effects of shear, provides appropriate microclimate management, and is appropriate for the individual's mobility, positioning needs, and level of risk.

Even the most advanced support surface cannot eliminate all mechanical forces. Proper positioning, scheduled repositioning, transfer techniques, and individualized care remain essential components of successful wound management.

Healing Requires More Than Just a Good Mattress

Support surfaces should never be viewed as a standalone treatment. Successful pressure injury management requires addressing the entire clinical picture: nutrition and hydration, blood flow and vascular status, infection control, moisture management, repositioning schedules, seating and wheelchair support, transfer techniques, and any medical conditions affecting healing. Every factor that contributes to tissue injury should be evaluated alongside every factor that promotes tissue repair.

What Is Stopping the Pressure Injury From Staying Closed?

Perhaps the better question is not "why isn't this wound healing?" but "what forces are preventing this wound from healing and remaining closed?" That subtle shift moves the focus from simply treating the wound to identifying and eliminating the ongoing mechanical stresses that may be disrupting the body's natural healing process. For individuals at low risk, improving pressure redistribution may be enough; for others, reducing tissue deformation, minimizing shear, optimizing positioning, or selecting a support surface that better addresses their specific clinical needs may provide the missing piece.

The body's ability to heal is remarkable. Sometimes the challenge is not that healing has stopped, it is that healing is continually being interrupted. Recognizing that possibility may lead to more effective support surface selection, better clinical decision-making, and ultimately, improved outcomes for individuals living with pressure injuries.

Because so many individual factors, medical history, mobility, caregiving capacity, and the home or facility environment, affect which support surface and positioning approach will actually help, this is not a decision to work through alone or by comparing product features online. If a wound is not progressing as expected, talk with a support surface expert. A specialist who understands the full range of surface technologies can evaluate the individual's specific situation and work alongside the wound care team to identify the solutions best suited to their needs.

Frequently Asked Questions About Pressure Sore Healing

Can a pressure injury be healing and still look unchanged on the surface?

Yes. Deep tissue injury forms at the bone-muscle interface and can remain hidden under intact-looking skin for days while damage progresses underneath, so a wound can be actively cycling through repair and reinjury without visible surface change.

What is the difference between pressure and shear in pressure injuries?

Pressure acts perpendicular to the skin and compresses blood vessels directly beneath the load. Shear is a parallel, diagonal force created when skin stays relatively fixed against a surface while deeper tissue and bone shift beneath it, distorting and stretching tissue layers against each other.

What is a deep tissue injury (DTI)?

A deep tissue injury is damage that begins at the bone-muscle interface from combined pressure and shear, presenting as intact or non-intact skin with persistent, non-blanchable deep red, maroon, or purple discoloration. It is dangerous because the visible surface often understates how advanced the underlying damage is.

Does raising the head of the bed increase shear risk at the tailbone?

Yes. When the head of the bed is elevated, gravity pulls the skeleton toward the foot of the bed while skin stays anchored by friction against the sheet, concentrating shear over the sacrum and coccyx. Limiting head-of-bed elevation and duration is a standard part of pressure injury prevention, though the appropriate angle should always be individualized with a clinician given other medical needs, such as feeding tubes or aspiration risk.

When should a support surface expert be consulted for a non-healing wound?

When a pressure injury is not progressing as expected despite appropriate wound care, involving a support surface specialist alongside the wound care team can help identify whether ongoing pressure, shear, deformation, or microclimate issues from the current surface or positioning routine are interrupting healing.

References

1. Edsberg LE, Black JM, Goldberg M, McNichol L, Moore L, Sieggreen M. Revised National Pressure Ulcer Advisory Panel Pressure Injury Staging System. Journal of Wound, Ostomy and Continence Nursing, 2016.
2. Gefen A. The Effects of Pressure and Shear on Capillary Closure in the Microstructure of Skeletal Muscles. Annals of Biomedical Engineering, 2008.
3. National Pressure Injury Advisory Panel, Support Surface Standards Initiative (S3I). Terms and Definitions Related to Support Surfaces, 2024.
4. Nixon J, et al. Pressure Relieving Support Surfaces for Pressure Ulcer Prevention (PRESSURE 2): Clinical and Health Economic Results of a Randomised Controlled Trial. eClinicalMedicine, 2019.
5. Shi C, Dumville JC, Cullum N, et al. Alternating Pressure (Active) Air Surfaces for Preventing Pressure Ulcers. Cochrane Database of Systematic Reviews, 2021.
6. New Insights into the Role of Cellular Senescence and Chronic Wounds. Frontiers in Endocrinology, 2024.
7. Pressure Ulcer. StatPearls, NCBI Bookshelf, National Library of Medicine (updated periodically).