**3.3 Preserving residual limb health**

Skin ulcers are typically the end result of vascular insufficiency and improper skin barrier function. Reperfusion of blood, as seen in reactive hyperemia, to nutrient- and oxygen-deprived tissue is another causative factor of tissue injury that contributes to ulcer formation [28]. In lower-limb amputation, this was identified

#### **Figure 5.**

*Prosthesis*

sis and back pain.

habits are common features of a vast majority of amputees who use a prosthesis resulting in at least one deviation or problem. The increased load or weight is often placed on the intact limb as a result of these deviations can cause discomfort or pain in the joints and lead to some form of degenerative joint disease or disability in extreme cases. Three of the most common secondary complications in lower-limb amputees due to compensatory and/or altered stresses are osteoarthritis, osteoporo-

About 75% of patients with lower-limb prosthetics have skin problems [26, 27]. The lack of a normal pressure-distributing anatomy the residual limb is prone to issues such as elevated shear forces, stress risers, increased humidity, and prolonged moist contact within the prosthesis, which can contribute to ulceration. Ulcers or pressure sores, are the most common skin conditions in prosthetic users [24]

*Laser speckle imaging (LSI) for skin perfusion. (A) Black box over transtibial amputee represents field of view (FOV) for perfusion mapping and quantification. (B) Representative perfusion maps acquired pre- and post-activity (over-ground walking) in sound and residual limb. (C) Perfusion was measured by laser Doppler flowmetry out-of-socket with liner on (O) and in-socket while resting with weight bearing on the residual limb (I) under SoC (black bar) and EVS (white bar) conditions. Data are mean perfusion units ± SE (shown as error bar). \*p<0.05 O vs I within gp at time point (reprinted with permission from Rink CL et al. [33]).*

**50**

**Figure 4.**

*Hyperspectral imaging for skin oxygen saturation. (A) Black box represents field of view (FOV) for qualification of tissue oxygen saturation (StO2) in residual limb. (B) Representative oxygen saturation map. (C) Reactive hyperemia quantified as percent changed in tissue oxygen saturation pre- and postactivity was determined in standard of care (SoC) (black bar) and EVS (white bar) socket systems at baseline and after 16 weeks of use (final). Data are mean ± SE (shown in error bar), \*p < 0.05 SoC vs. EVS (reprinted with permission from Rink et al. [33]).*

#### **Figure 6.**

*Transepidermal water loss (TEWL) for skin barrier function. (A) Schematic of TEWL probe over the skin as it measures differences between relative humidity of ambient air and directly above skin. (B) Photograph of a TEWL measurement. (C) TEWL was measured 15 min after socket doffing in people with transtibial and transfemoral amputation (n = 10) under standard of care (SoC) (black bar) and EVS (white bar) conditions. Data shown are from areas of high stress and low stress combined. Data shown are from areas of high stress and low stress combined. Data are mean ± SE (shown as error bars). \*p < 0.05 SoC vs. EVS within time point. †p<0.05 baseline vs. final within prosthesis group (reprinted with permission from Rink et al. [33]).*

**Figure 7.**

*Surface electrical capacitance for skin hydration. (A) Close-up view of SEC probe. Photograph of SEC measurement collection from a subject. SEC measurements from (B) transtibial and (C) transfermoral subjects immediately after liner removal and after equilibration with air for 15 min (reprinted with permission from Rink et al. [33]).*

#### **Figure 8.**

*Silicone gel probe holder for in-liner measurement. (A) Temperature, transcutaneous oxygen measurement (TCOM) wand laser Doppler flowmetry (LDF) probes were embedded in a silicone gel insert to enable realtime measurement of limb temperature, oxygenation, and perfusion respectively. (B) Placement of probes on residual limb of transtibial participant. Oxygen permeable TegadermTM was used to adhere the TCOM probe to the limb. (C) The silicone gel insert enabled reproducible placement and spacing of probes and buffered against the liner from pressing probes tightly against skin (reprinted with permission from Rink et al. [33]).*

**53**

*Residual Limb Health and Prosthetics*

interfering with one another.

**Acknowledgements**

**Conflict of interest**

grant award W81XWH-16-2-0059.

**4. Summary and conclusions**

functional artificial limb for long-term use.

The authors declare no conflict of interest.

*DOI: http://dx.doi.org/10.5772/intechopen.83819*

as a complication of prosthesis use in the early 1960s [29]. Key among the factors to monitor in attempting to preserve and promote residual limb health would be

There are few examples of evidence based research related to the effect of socket systems, particularly elevated vacuum suspension systems on limb health [30–32]. A recent study was the first to directly test the effect of EVS on residual-limb skin health and blood flow [20]. This study used a standardized non-invasive imaging (**Figures 4**-**7**) approach with a combination of out-of-socket imaging (e.g., hyperspectral imaging, transepidermal water loss (TEWL) and surface electrical capacitance (SEC)) and in-socket imaging (e.g., transcutaneous oximetry (TCOM), laser Doppler flowmetry (LDF)) [20, 33]. Outcomes of this study identified that elevated vacuum suspension socket systems promote better residual limb skin physiology by preserving the skin barrier function (TEWL measurements), rescuing against loss of tissue oxygenation during activity and attenuating reactive hyperemia. Customized test sockets for people with TT and TF amputations with embedded in-socket silicone probe holder (**Figures 3** and **8**) housed perfusion (LDF) and tissue oxygen (TCOM) measurement probes and enabled multiple temporal measurements from the same sites to be taken in study without the individual probes

Residual limb skin health is a key determinant of quality of life for individuals with lower limb amputation. Skin health problems, caused by shear forces and stress to the residual limb, are known to affect the ability of individuals with lower limb loss to perform household tasks, use their prosthesis, engage in social functions, and participate in sports. Therefore, objective measures to during socket fitting combined with real-time monitoring of skin physiological parameters such as barrier function, hydration and perfusion are likely to provide a better fitting and

The authors acknowledge grant funding from the United States Department of Defense (DoD) Congressionally Directed Medical Research Programs (CDMRP)

maintenance of skin barrier function, perfusion and oxygenation.

#### *Residual Limb Health and Prosthetics DOI: http://dx.doi.org/10.5772/intechopen.83819*

*Prosthesis*

**Figure 7.**

*Rink et al. [33]).*

*Surface electrical capacitance for skin hydration. (A) Close-up view of SEC probe. Photograph of SEC measurement collection from a subject. SEC measurements from (B) transtibial and (C) transfermoral subjects immediately after liner removal and after equilibration with air for 15 min (reprinted with permission from* 

*Silicone gel probe holder for in-liner measurement. (A) Temperature, transcutaneous oxygen measurement (TCOM) wand laser Doppler flowmetry (LDF) probes were embedded in a silicone gel insert to enable realtime measurement of limb temperature, oxygenation, and perfusion respectively. (B) Placement of probes on residual limb of transtibial participant. Oxygen permeable TegadermTM was used to adhere the TCOM probe to the limb. (C) The silicone gel insert enabled reproducible placement and spacing of probes and buffered against the liner from pressing probes tightly against skin (reprinted with permission from Rink et al. [33]).*

**52**

**Figure 8.**

as a complication of prosthesis use in the early 1960s [29]. Key among the factors to monitor in attempting to preserve and promote residual limb health would be maintenance of skin barrier function, perfusion and oxygenation.

There are few examples of evidence based research related to the effect of socket systems, particularly elevated vacuum suspension systems on limb health [30–32]. A recent study was the first to directly test the effect of EVS on residual-limb skin health and blood flow [20]. This study used a standardized non-invasive imaging (**Figures 4**-**7**) approach with a combination of out-of-socket imaging (e.g., hyperspectral imaging, transepidermal water loss (TEWL) and surface electrical capacitance (SEC)) and in-socket imaging (e.g., transcutaneous oximetry (TCOM), laser Doppler flowmetry (LDF)) [20, 33]. Outcomes of this study identified that elevated vacuum suspension socket systems promote better residual limb skin physiology by preserving the skin barrier function (TEWL measurements), rescuing against loss of tissue oxygenation during activity and attenuating reactive hyperemia. Customized test sockets for people with TT and TF amputations with embedded in-socket silicone probe holder (**Figures 3** and **8**) housed perfusion (LDF) and tissue oxygen (TCOM) measurement probes and enabled multiple temporal measurements from the same sites to be taken in study without the individual probes interfering with one another.

### **4. Summary and conclusions**

Residual limb skin health is a key determinant of quality of life for individuals with lower limb amputation. Skin health problems, caused by shear forces and stress to the residual limb, are known to affect the ability of individuals with lower limb loss to perform household tasks, use their prosthesis, engage in social functions, and participate in sports. Therefore, objective measures to during socket fitting combined with real-time monitoring of skin physiological parameters such as barrier function, hydration and perfusion are likely to provide a better fitting and functional artificial limb for long-term use.
