Managing Daily Residual Limb Volume Changes: An Australian Case Study of the Ethnocare Overlay

Maintaining a consistent prosthetic socket fit throughout the day remains a common challenge for people with limb loss.

Even when a socket fits appropriately at delivery, the residual limb can change in volume over the course of the day due to factors including fluid shifts, edema, activity, diet, medication and longer-term physiological changes. Because the socket itself is rigid, these changes can affect the interface between the residual limb and the prosthesis. 

Traditional management often relies on adding or removing prosthetic socks as limb volume changes.

An Australian clinical case study explored whether the Ethnocare Overlay, our inflatable prosthetic device, could offer an alternative approach.

Study Objective

The case study evaluated whether the Overlay could make daily residual limb volume changes easier to manage while maintaining or improving several clinically relevant outcomes:

• Comfort during daily activities

• Ease of adjusting socket fit

• Stability and security

• Accommodation of daily limb volume changes

• Walking and gait

• Pain

• Overall satisfaction

The Overlay was compared with conventional prosthetic socks. 

Methodology

Eight prosthetic users participated in the evaluation:

6 transtibial users and 2 transfemoral users.

Five participants were new to the Overlay. They first used their regular prosthetic socks for two weeks, completed a standardized questionnaire, then used the Overlay for two weeks and completed the same evaluation again.

Three additional participants were existing Overlay users and completed the same standardized evaluation along with a retrospective comparison to their previous experience with prosthetic socks.

Participants generally had moderate to high daily residual limb volume fluctuations, typically requiring more than two ply of adjustment per day. 

Results: New Overlay Users

The five new users provide the most direct within-subject comparison between prosthetic socks and the Overlay.

One of the most practical differences was the frequency with which users needed to remove their prosthesis or clothing to adjust socket fit.

This decreased from:

2.2 times per day with prosthetic socks → 0.6 times per day with the Overlay. 

Several other outcomes improved:

Comfort during daily activities
6.6 → 8.6 / 10
+30%

Ease of adjusting socket fit
6.0 → 7.6 / 10
+27%

Effectiveness in managing daily volume changes
6.6 → 9.4 / 10
+42%

Stability and security
7.8 → 9.2 / 10
+18%

Walking and gait
7.6 → 9.4 / 10
+24% 

Results Across All Eight Participants

When all participants were considered together, average Overlay scores were:

9.1/10 for comfort
8.5/10 for ease of adjustment
9.5/10 for stability
9.6/10 for managing daily volume changes
9.6/10 for walking and gait

Overall satisfaction was 9.1/10.

Importantly, all eight participants preferred the Overlay over prosthetic socks for managing their socket fit. 

Why Adjustable Volume Management Matters

The purpose of volume accommodation extends beyond simply filling space inside a socket.

For users relying on prosthetic socks, changing socket fit may require stopping an activity, accessing the residual limb, removing the prosthesis and changing sock ply.

With the Overlay, participants could instead modify the amount of air in the interface while the prosthesis remained in place.

In this case study, the average number of daily removals for fit management decreased from 2.2 to 0.6 among new users. 

This suggests that adjustable interfaces may have an important role not only in socket fit, but also in making volume management more convenient during everyday activities.

Interpreting the Results

These findings are encouraging, but they should be interpreted appropriately.

This was a small case study involving eight participants, including only two transfemoral users. The results therefore cannot establish clinical effectiveness all the amputee population.

Conclusion

Within this Australian case study, use of the Ethnocare Overlay was associated with improved ratings for volume management, comfort, socket stability and gait compared with participants' previous prosthetic sock management.

Perhaps most importantly from a daily-use perspective, users needed to remove their prosthesis considerably less frequently to adjust their fit.

For prosthetic users experiencing meaningful daily residual limb volume fluctuations, adjustable interfaces such as the Overlay may provide another option for managing changes in socket fit throughout the day.

Interested in learning whether the Overlay could be appropriate for you or your patients?

Contact your local distributor
Contact Ethnocare
or
Contact your prosthetist to learn more!