Morphological characteristics of the human skin over posterior aspect of heel in the context of pressure ulcer development

Using ultrasound elastography to monitor human soft tissue behaviour during prolonged loading: A clinical explorative study

“…These empirical findings might be explained by anatomical differences: The dermis is a dense fibrous structure compared to underlying subcutaneous tissues at the sacral and upper back areas. Whereas heel skin is anchored to the bone by thick dense fibrous septa, which ramifies throughout a heel pad and connects the underlying periosteum of the calcaneus, to create a dense cup-like structure [29,30]. The subcutaneous heel tissue is also much stiffer compared to the sacral and upper back areas and shear wave velocities are therefore comparable to the heel skin stiffness.…”

Subepidermal moisture detection of heel pressure injury: The pressure ulcer detection study outcomes

“…Heel PrIs may present as fluid‐filled or blood‐filled blisters or black dry eschar areas that over time re‐epithelialize under the eschar . The severity of a heel PrI does not always reflect the degree of pressure applied . DTIs and stage 3 and 4 full‐thickness PrIs are not necessarily caused by more pressure than superficial lesions (which may also involve friction forces as a contributing factor) …”

“…Several anatomical features make the heels more prone to PrI, and specifically deep tissue injury (DTI) than some other areas of the body. First, when a person is lying supine, the posterior aspect of the heel has limited subcutaneous fat volume and includes the stiff Achilles tendon, making the site susceptible to pressure which, if unrelieved, can result in tissue breakdown and necrosis . Second, the heel consists of skin overlying avascular fat and reticular dermis present in fibrous septa compartments and supplied by blood vessels including the subdermal plexus, periosteal plexus, and connecting vessels between the reticular dermis and the calcaneus bone .…”

“…Third, the contact surface area on the posterior heel is small and there is limited fat tissue available in the posterior heel when pressure is exerted directly on the calcaneous bone. Finally, there is only one muscle in the heel, a thin layer of panniculus carnosus muscle that along with the subcutaneous fat is likely involved in PrI development . As noted, some of the heel tissues are stiffer and less elastic than in other areas of the foot and body .…”

“…Finally, there is only one muscle in the heel, a thin layer of panniculus carnosus muscle that along with the subcutaneous fat is likely involved in PrI development . As noted, some of the heel tissues are stiffer and less elastic than in other areas of the foot and body . There is evidence from finite element modelling that stiffer soft tissue is less capable of deforming and alleviating the stress and strain from pressure, contributing to increased PrI susceptibility .…”