Socket Discomfort After Below-Knee Amputation

Undergoing a transtibial amputation is a life-altering experience, often leaving below-knee amputees with numerous questions about how to adapt and thrive post-surgery. How long will rehabilitation take? How should I care for my limb after surgery? What is the best way to find a prosthesis that suits my needs? These concerns can feel overwhelming as amputees navigate the early stages of limb loss, such as experiencing phantom limb pain, swelling, and socket discomfort¹.

In this blog, we explore the prevalence of socket discomfort in below-knee amputees, its known causes, and innovative solutions that aim to alleviate this common issue.

How Common Is Socket Discomfort?

Socket discomfort is a pervasive problem among below-knee amputees and is one of the most impactful factors throughout their rehabilitation journey. A 2020 study by Turner and McGregor revealed that socket fit issues were cited as the leading factor affecting rehabilitation by 48% of amputees and 65.7% of clinicians³. The socket is a critical point of connection, or “interface,” between the patient and the prosthetic device. An adequate socket requires a precise fit, appropriate load transmission, stability, and control. In fact, the fit of the socket is often a deciding factor in the success or failure of the prosthesis itself. A well-fitting socket is essential for comfort, control, and an overall successful rehabilitation. Unfortunately, many amputees find themselves unable to use their prostheses due to poor socket fit, inadequate biomechanics, and limited control, contributing to a prosthesis abandonment rate of around 25–57%³.

What Causes Socket Discomfort?

Several factors contribute to socket discomfort. The shape and materials used in the socket, along with the suspension system, play significant roles in how pressure, stress, temperature, and volume changes affect the residual limb. These elements are interconnected; for instance, volume fluctuations in the residual limb can lead to a poor fit, resulting in discomfort, sweating, skin irritation, and rubbing².

In lower limb amputees, these issues can lead to something known as the "pistoning effect," where the limb moves within the socket during activity. This relative movement can compromise both comfort and stability, making it crucial to achieve an optimal fit for long-term use. If the socket does not fit well, it can hinder mobility and impact the user’s quality of life, leading to frustration and discouragement⁴.

To combat factors that contribute to poor socket fit, it is standard practice for amputees to use liners, due to their ability to adhere to the skin, provide an additional barrier of protection, and help distribute loads. Previously, prosthetic liners were made of open- and closed-cell foams, such as Pelite. Today, many clinicians recommend silicone or other elastomer-based liners, rolled on the residual limb, for increased durability and improved cushioning.

Innovative Solutions for Socket Discomfort

The traditional creation of a prosthetic socket involves a detailed process that starts with precise measurements and a casting of the residual limb. This cast is then filled with plaster to create a positive mold, which undergoes a process known as "rectification" to ensure an optimal fit. The overall design of the socket is critical to patient comfort and rehabilitation success, relying heavily on the prosthetist’s skill and attention to detail during casting and rectification¹.

While this manual process remains the standard for creating prosthetic sockets, new high-tech methods like 3D scanning have begun to impact the prosthetics and orthotics (P&O) industry, offering solutions to previous inaccuracies and human error. As the industry evolves, it is important to understand how both traditional and innovative approaches to socket creation can impact patient comfort.

Limber is a manufacturer at the forefront of this evolution, creating precise transtibial prosthetic devices through 3D scanning, design, and printing. Limber’s digital fabrication process allows clinicians to scan patients' residual limbs (or existing prostheses) and upload de-identified measurement data, which is then used to create a custom digital model. This model is printed using high-quality, proprietary materials that have been extensively tested and validated through ISO and similar testing protocols.

The application of 3D printing in prosthetics is particularly promising because it allows for rapid production and customization, ensuring that each socket fits the individual’s unique anatomy. This personalization often enhances comfort and functionality, addressing common issues that many amputees face with traditional sockets.

In this era of technological advancement, the multitude of options available can be overwhelming for amputees seeking the right prosthesis. At Limber, the focus remains firmly on patient care. Our team is dedicated to providing personalized support, ensuring that each of our partner clinicians and their patients receive the most suitable prosthetic solution tailored to their specific needs.

To learn more about Limber’s digital process and flagship product, the UniLeg, visit our website.

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Sources

1. Hanger Clinic Below-Knee Amputation Patient Care Manual. Hanger Clinic, https://hangerclinic.com/wp-content/uploads/patient-care-manual-below-knee.pdf.

2. "15 Skin Problems Amputees Experience & How to Solve Them." Amputee Store, https://amputeestore.com/blogs/prosthetic-guides/15-skin-problems-amputees-experience-how-to-solve-them.

3. Turner, S., & McGregor, A. H. (2020). Perceived Effect of Socket Fit on Major Lower Limb Prosthetic Rehabilitation: A Clinician and Amputee Perspective. Archives of Rehabilitation Research and Clinical Translation, 2(3), 100059. https://doi.org/10.1016/j.arrct.2020.100059

4. "Lower Limb Prosthetic Sockets and Suspension Systems." Physiopedia, https://www.physio-pedia.com/Lower_Limb_Prosthetic_Sockets_and_Suspension_Systems.