Influence of Body Fat Percentage on the Development of Deep Tissue Injuries in Transfemoral Amputees

ABSTRACT Background A deep tissue injury (DTI) occurs under healthy skin, in skeletal muscle tissue overlying bony prominences, and progression of the wound continues subcutaneously until skin breakdown. It is a silent process, and it is essential to establish potentially susceptible individuals for their risk of developing a DTI. An analysis of the incidence of the fat tissue thickness or body mass index (BMI) on the stresses and strains in muscular tissue is made to establish its influence on the generation of pressure ulcers (PU) in the amputee’s residual limb. Methods In this research, a three-dimensional modeling of the residual limb of a transfemoral amputee is performed, including skin, fat tissue, muscle, socket prosthesis, and residual femur. The loading conditions are established for the support phase during the normal gait cycle, the standing and walking through stairs of a transfemoral amputee with 88 kg weight and 1.7 m tall. Results Cell-death in muscle tissue begins to occur when compressive stress reaches values greater than 32 kPa and deformations exceed 65%. These conditions manifest more readily in adipose tissue thicknesses below 6 mm and in the distal femur area, specifically in the amputation zone where the muscle contacts the bone. Conclusions This research found that the distribution and concentration of critical stresses and strains to develop a DTI on transfemoral amputees are located in the muscle tissue near the distal area of the residual femur, mainly transmitted under the action of the bony prominence. Fat tissue works as a shock-damping material for the external loads over the stump, and it works in a very similar way to a fluid that adjusts itself according to the needs, indicating the importance of this tissue for preventing injuries. As the fat tissue thickness (FTT) increases, the stress and strain values decrease, reaching reduction values greater than 20% from 6 mm to 8 mm FTT. The aforementioned indicates that having fat percentages under 10% or thickness of fat tissue under 6 mm implies cell strains higher than the death threshold of 65% that would favor DTI apparition. Clinical Relevance This research suggests that proper assessment and establishment of optimal residual limb BMI values are crucial for preventing DTI in transfemoral amputation patients.