How Ultrasound Tech Can Help Improve Below-Knee Prosthetic Socket Fit
Reading Time: 4 minutes
Below-knee prosthetic users often encounter challenges in achieving a comfortable prosthetic socket fit, resulting in residual limb pain and instability of the residual limb-socket connection. A potential solution requires improving how prosthetists evaluate the impact of prosthetic adjustments on the loading of the residual limb onto the socket.
To address this, researchers have explored the feasibility of using imaging technologies, like ultrasound, to enable prosthetists to observe the movement of the residual limb within the socket.
Why ultrasound?
Conventional imaging methods, such as X-rays, have been used to examine residual bone movement within the prosthetic socket. However, X-rays can only capture images in static situations to represent a specific gait phase. To solve a fit issue, dynamic images are better.
This led researchers to consider CT scans and MRIs, which can provide more detailed images. However, these methods are often inaccessible to most people due to cost.
Ultrasound, on the other hand, is a cost-effective and straightforward method used to monitor musculoskeletal conditions. It has the potential to be the diagnostic tool of choice for understanding how prosthetic devices interact with bones and soft tissues.
Furthermore, using ultrasound to measure residual limb movement in below-knee prosthetic users offers several advantages. One such advantage is ultrasound provides real-time insights into dynamic movement. Unlike other methods, ultrasound would give prosthetists a better understanding of how the residual limb interacts with the prosthetic socket and how soft tissues deform during prosthesis use.
However, its current use in prosthetics is limited.
Researchers conducted a study to assess the feasibility of using B-mode ultrasound to monitor residual limb movement within the socket. B-mode ultrasound is specified because it’s ideal for showing bone, soft tissue, and organs. The study was published in the Scientific Reports journal on April 27, 2024.
The study
The researchers studied five participants who had used a below-knee prosthesis for at least one year. Their residual limbs were also evaluated as suitable for sub-atmospheric pressure fitting by a certified prosthetist.
Using a Samsung HM70A ultrasound system, the researchers observed the participants’ residual limbs inside the socket while doing three prosthetic stepping conditions: forwards, backward, and sideways.
The study visualized the movement of the residual limb inside the prosthetic socket. The researchers noted that the connection between the residual limb and the prosthetic socket should be treated as a “pseudo-joint” with its own characteristics rather than just a stiff connection between the prosthesis and the skeletal system.
Besides revealing how the residual bone moves inside the socket, the study also provided insight into how this movement affects the surrounding soft tissues. The researchers noted that the data could be used to research further how stress, strain, and bone movement are related. This could help us understand how changes to the socket design affect bone movement and tissue damage.
Benefits
Once more prosthetists widely use B-mode ultrasound to improve prosthetic socket fit, the researchers hope that more below-knee prosthesis users can move freely and naturally with better control. It’ll also help reduce discomfort, which means longer and more comfortable use of the prosthetic leg.
Ultimately, the goal is greater independence as improved functionality allows users to perform more tasks independently.
The bottom line
This study is the first to successfully track residual bone movement within a prosthetic socket while the participants execute different stepping tasks. Using this technology could enhance our understanding of the causes and effects of residual bone movement within the prosthetic socket. The researchers hope this study will spur further studies with a larger sample size, which would fast-track the use of ultrasound tech in most prosthetic clinics.
While it will take some time for this method to trickle down to most below-knee prosthetic users, the science seems to be on the right track.
