Adjustable-volume prosthetic sockets may significantly improve comfort, mobility, satisfaction and quality of life for lower-limb prosthesis users, according to a large real-world study involving more than 400 adults.
Researchers from the Hanger Institute for Clinical Research and Education examined outcomes among 444 people who changed from conventional fixed-geometry sockets to adjustable-volume designs between 2023 and 2025.
Mean socket comfort scores increased from 5.59 to 7.16 on a ten-point scale, while prosthetic mobility, overall quality of life, general satisfaction and satisfaction with walking ability all improved significantly after the transition.
The findings reinforce the importance of the socket as the interface between the person and the prosthesis. Even the most advanced prosthetic knee or foot may offer limited benefit when the socket is uncomfortable, unstable or unable to accommodate changes in the residual limb.
For prosthetic services across the Middle East, Africa and South Asia, adjustable designs could offer an additional way to manage fluctuating limb volume, reduce dependence on prosthetic socks and give users greater control over day-to-day fit.
The study followed 444 lower-limb prosthesis users
The retrospective cohort study included adults receiving care at multiple prosthetic clinics in the United States.
Participants completed assessments before receiving an adjustable-volume socket and again between eight days and one year after delivery.
The group had a mean age of 55.7 years. Approximately 60% had transtibial amputations and 40% had transfemoral amputations. Vascular disease and diabetes accounted for 57.2% of amputations in the study population.
The researchers reported improvements across both amputation levels:
- Transfemoral users’ average comfort scores increased from 5.42 to 7.10.
- Transtibial users’ scores increased from 5.69 to 7.20.
- Prosthetic mobility scores increased from 44.8 to 46.9.
- Quality-of-life scores increased from 6.87 to 7.42.
- General satisfaction increased from 6.68 to 7.27.
- Satisfaction with walking ability increased from 5.68 to 6.66.
Greater improvements in comfort were also associated with longer daily prosthesis wear, better mobility and higher overall satisfaction.
This relationship is clinically important because socket discomfort is not simply an inconvenience. It can reduce wearing time, restrict activity and eventually contribute to partial or complete abandonment of the prosthesis.
Why residual-limb volume changes matter
A conventional laminated socket is manufactured around the residual limb’s shape at a particular point in time.
The residual limb, however, is not static.
Its volume can change because of:
- Fluid movement during the day
- Changes in activity
- Heat and perspiration
- Weight gain or loss
- Tissue remodelling after amputation
- Progressive muscle atrophy
- Medication and medical conditions
- Dialysis or cardiovascular disease
When the limb becomes smaller, the socket may feel loose and allow excessive movement. This can reduce control and create friction or localised pressure.
When the limb swells, the socket may become tight, painful or difficult to put on.
Conventional management often involves adding or removing prosthetic socks. While this can be effective, it may require repeated adjustments throughout the day and does not always address localised changes in shape.
Adjustable-volume systems allow the user or clinician to change aspects of the socket’s dimensions or compression without manufacturing an entirely new socket.
Adjustment gives users more control
Adjustable sockets use different mechanisms depending on the design.
These may include:
- Dials and cable systems
- Panels that tighten or release
- Straps and buckles
- Flexible brims
- Movable socket sections
- Modular structural elements
The objective is not necessarily to make the whole socket uniformly tighter.
A well-designed system may allow targeted adjustment in selected areas while maintaining appropriate suspension, load distribution and control.
This can give users greater independence when their residual limb changes during the day.
Instead of waiting for a clinical appointment or managing fit exclusively through socks, the person may be able to make a small adjustment before walking, working or resting.
This sense of control may be especially valuable for people who live far from their prosthetic clinic.
Potential relevance for IMEA prosthetic services
Residual-limb volume management can be particularly challenging across the IMEA region.
High temperatures may increase perspiration and affect socket comfort. Long travel distances may make repeated clinic visits difficult, while limited public transport can restrict access for prosthesis users.
Patients in rural, humanitarian or lower-resource environments may also have fewer opportunities for socket replacement and adjustment.
Adjustable-volume technology could potentially help by:
- Extending the useful period of a socket
- Allowing day-to-day fit changes
- Reducing some emergency adjustment visits
- Improving tolerance during volume fluctuation
- Supporting users who travel long distances for care
- Giving patients greater involvement in managing their prosthesis
However, adjustable sockets should not be presented as a substitute for professional follow-up.
A loose or painful socket may indicate a problem that cannot be corrected simply by tightening a mechanism. The user may require socket modification, liner review, alignment adjustment, medical assessment or a complete replacement.
Diabetes makes volume management particularly relevant
More than half of the study population underwent amputation because of vascular disease or diabetes.
People with dysvascular amputations may experience residual-limb volume changes alongside fragile skin, reduced sensation, cardiovascular disease and other health complications.
An adjustable socket could help manage some fluctuations, but this population also requires particularly careful monitoring.
A person with neuropathy may not recognise excessive pressure or early skin damage. Giving the user the ability to tighten a socket must therefore be accompanied by clear education about skin inspection and safe adjustment.
Clinical follow-up should assess:
- Pressure and redness
- Skin breakdown
- Residual-limb circulation
- Liner condition
- Socket alignment
- Changes in body weight
- The health of the remaining foot
- The person’s ability to use the adjustment mechanism safely
Adjustability should improve fit without transferring responsibility for all clinical decisions to the patient.
The findings support earlier smaller studies
The larger Hanger Institute study adds to earlier research on adjustable socket designs.
A randomised controlled trial involving 29 people with unilateral transfemoral amputations compared three commercially available adjustable sockets with conventional laminated sockets.
Participants trialled each adjustable design at home for four weeks. When the fittings were successful, some designs improved perceived utility, walking, social burden, fit and sitting comfort.
However, substantial numbers of sockets were abandoned during the acclimatisation period because of discomfort or instability. Abandonment rates ranged from 24% to 41%, depending on the design.
That trial concluded that adjustable-volume sockets can provide an alternative to laminated sockets, but that future research should identify which patients are most likely to succeed with particular designs.
The contrast between the two studies is useful.
The newer study shows meaningful improvements across a large real-world population, while the controlled trial demonstrates that adjustable sockets are not automatically successful for every patient.
Patient selection remains essential
An adjustable socket may be particularly useful for people who:
- Experience predictable daily volume changes
- Need to alter socket tension for different activities
- Have difficulty managing multiple sock layers
- Live far from their prosthetist
- Have undergone recent tissue remodelling
- Can understand and operate the adjustment system
- Are able to monitor their skin reliably
It may be less appropriate for patients with:
- Severe cognitive impairment
- Poor hand function that prevents adjustment
- Unhealed wounds
- Unstable residual-limb tissue
- Significant contractures
- Severe skin fragility
- Inability to recognise pressure problems
- A need for extensive structural correction
The prosthetist must also consider activity level, suspension, body weight, component clearance and the physical demands placed on the socket.
An adjustable socket is a clinical option rather than a universal replacement for conventional laminated designs.
Training is required for clinicians and patients
Introducing adjustable-volume sockets requires more than purchasing a new component.
Prosthetists need training in:
- Patient selection
- Casting or digital shape capture
- Socket configuration
- Structural assembly
- Suspension and alignment
- Safe adjustment ranges
- Troubleshooting
- Documentation
- Follow-up protocols
Patients need clear instructions covering:
- When and how to adjust the socket
- How much adjustment is safe
- When to loosen rather than tighten
- How to inspect the skin
- When to stop using the prosthesis
- When to contact the clinic
- How to maintain the adjustment mechanism
The device should be fitted as part of a structured clinical pathway rather than supplied as a self-management product without supervision.
Adjustable sockets may support outreach models
The technology could be valuable within hub-and-spoke prosthetic systems.
A specialist centre could complete the initial assessment, prescription and fitting. Regional clinics or trained outreach staff could then support routine reviews and minor adjustments.
Digital follow-up may also be useful where connectivity allows.
A prosthesis user could discuss fit changes through a video consultation before deciding whether travel to the main centre is necessary.
This could be particularly relevant in countries where qualified prosthetists are concentrated in capitals or major cities.
Adjustability may reduce some unnecessary journeys, although it will not eliminate the need for in-person assessment when significant problems arise.
Cost and repairability will affect regional adoption
The clinical benefits of an adjustable socket must be considered alongside cost, durability and maintenance.
Services should ask:
- Is the system affordable within the local reimbursement model?
- Are replacement cables, panels or fasteners available?
- Can the mechanism tolerate dust, humidity and heavy use?
- Can it be repaired locally?
- Does the supplier provide technical support?
- Will the user still be able to wear the prosthesis if one part fails?
- Is there evidence supporting the specific design?
A socket that performs well initially but depends on unavailable proprietary parts may create long-term problems.
For humanitarian and lower-resource settings, simple and robust adjustability may be more useful than a complex system requiring overseas servicing.
Outcome measurement should become routine
The study demonstrates the value of collecting patient-reported outcomes before and after a socket change.
Prosthetic clinics can use standard measures to assess:
- Socket comfort
- Daily wearing time
- Mobility
- Satisfaction
- Walking confidence
- Quality of life
- Skin problems
- Frequency of adjustments
- Device abandonment
These data can help clinicians determine which patients benefit most from adjustable designs.
They can also support reimbursement discussions by showing whether a higher initial cost is associated with improved use, fewer socket problems or reduced replacement needs.
For IMEA clinics, even a simple outcome registry could generate valuable regional evidence.
Most published adjustable-socket research comes from developed healthcare systems. Local studies are needed to assess performance in hotter climates, rural settings and different patterns of trauma and vascular disease.
The study has important limitations
The Hanger Institute research provides the largest reported longitudinal real-world dataset on adjustable-volume sockets, but it was not a randomised comparison.
Participants were assessed before and after receiving an adjustable socket, meaning that improvements cannot automatically be attributed entirely to socket design.
Other factors may have contributed, including:
- Receiving a newer socket
- Changes in alignment
- New liners or components
- Additional clinical attention
- Increased motivation
- Differences in follow-up timing
The study was also conducted within US clinics, and the findings may not transfer directly to every health system or patient population.
Nevertheless, the consistency of improvements across transfemoral and transtibial users provides a strong basis for further research and carefully monitored clinical adoption.
Socket innovation deserves greater attention
Prosthetic development often focuses on visible technologies such as microprocessor knees, powered ankles and bionic feet.
The socket receives less public attention, but it determines how successfully those technologies connect to the human body.
An uncomfortable socket can make an advanced component unusable. A stable and adaptable socket can allow a relatively simple prosthesis to provide reliable daily mobility.
The new findings suggest that adjustable-volume sockets can create meaningful improvements for many lower-limb prosthesis users.
For IMEA prosthetic services, the opportunity is not to abandon conventional socket fabrication. It is to expand the available clinical options.
Patients need access to sockets that reflect the reality that residual limbs change throughout the day and over time.
The strongest services will combine adjustability with professional assessment, patient education, repair support and routine outcome monitoring.
A prosthetic socket should not merely contain the residual limb. It should support comfortable, confident and sustained participation in everyday life.
- The O&P EDGE – Adjustable-Volume Sockets Improve Comfort, Mobility and Quality of Life
- Hanger Institute study summary
- PubMed – Randomised trial of transfemoral adjustable-volume sockets
- International Society for Prosthetics and Orthotics
- World Health Organization – Rehabilitation
- World Health Organization – Prosthetics and orthotics services