Transtibial AmputationAS-TTNCT07592325
Clinical Evaluation of the Access Socket Flexible Socket for Transtibial Prosthesis
A study testing Access Socket (AS) and Rigid Socket (RS) in people with Transtibial Amputation and Lower Limb Amputation Below Knee, run by Union de Gestion des Etablissements des Caisses d'Assurance Maladie - Nord Est at 5 sites in France.
Trial summary
Transtibial amputation significantly impacts patient autonomy and quality of life, primarily due to the limitations of conventional rigid sockets, which restrict comfort and joint range of motion. Read more about this study
- Who is it for?
- Ages 18 years and older
- Conditions the study is for
- Transtibial Amputation, Lower Limb Amputation Below Knee
- What is being tested?
- Access Socket (AS) and Rigid Socket (RS)
- Type of treatment
- Medical device
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 25 participants
- Where
- 5 sitesFrance
- Study dates
- 27 Apr 2026to 30 Oct 2027
- Phase
- Interventional
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 years and older
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- Unilateral or bilateral transtibial amputation
- Currently fitted with a definitive carbon rigid socket
- Any residual-limb shape
- Any etiology
- Able to understand simple instructions, read, write, and provide informed consent - or able to be accompanied by a trusted person in case of inability to read/write autonomously
- Provided free written informed consent
- Aged 18 years or older
- Affiliated to a social security system
Who cannot join
- Use of hydroalcoholic solution (HAS) for socket donning
- Currently fitted with a provisional socket
- Neurological pathology limiting capacity to participate in activities
- Orthopedic pathology limiting capacity to participate in activities
- Pregnant or breastfeeding women
- Minors
Show all 9Show fewer
- Persons not under legal protection or unable to express consent
- Persons under guardianship or curatorship
- Persons under judicial protection
Trial locations and contacts
5 sites in 1 country. Contact the study team or a site near you to ask about taking part.
Jonathan Pierret, PhD contact
5 sites in 1 country
France5 sites, 5 recruiting
- Recruiting
Hôpital National d'Instruction des Armées (HNIA) Percy
Clamart, 92140
Marie Thomas-Pohl, MD, +33 1.41.46.62.82, marie.thomas@intradef.gouv.fr
Marie Thomas-Pohl, MD
- Recruiting
Hôpital Filieris de Freyming-Merlebach
Freyming-Merlebach, 57804
Catherine Achour, MD, +33 3 83 52 98 61, catherine.achour@filieris.fr
Catherine Achour
- Recruiting
CHU Grenoble Alpes - Hôpital Sud
Grenoble, 38434
Solène Maret, MD, +33 4 76 76 60 25, smaret2@chu-grenoble.fr
Solène MAret, MD
- Recruiting
Institut Régional de Médecine Physique et de Réadaptation (IRR) - Filière Locomoteur
Nancy, 54000
Christelle REQUENA, +33 3 83 52 98 61, christelle.requena@ugecam.assurance-maladie.fr
Jonathan Pierret, PhD, jonathan.pierret@ugecam.assurance-maladie.fr
- Recruiting
Insititution Nationale des Invalides
Paris, 75007
Joseph Bascou, PhD, +33 3 87 51 30 30, joseph.bascou@invalides.fr
About this study
Transtibial amputation significantly impacts patient autonomy and quality of life, primarily due to the limitations of conventional rigid sockets, which restrict comfort and joint range of motion. The Access Socket (AS) is an innovative prosthetic socket combining a rigid carbon-fiber structure in key load-bearing areas with flexible urethane-resin (ProtheFLEX®) zones in regions typically rigid in conventional sockets. This hybrid design aims to improve comfort and pressure distribution while preserving the mechanical properties required for ambulation.
The AS has already demonstrated benefits in transfemoral amputees and is now reimbursed in France for that population. A preliminary uncontrolled study in 12 transtibial amputees suggested significant improvements in perceived function, comfort, satisfaction, and mobility.
This multicenter, randomized, open-label, two-arm crossover study aims to compare the (AS) with the standard rigid socket (RS) in 25 adults with transtibial amputation. Participants will wear each socket for approximately 4 weeks (after a 1-2 week adaptation period) in a randomized order. The primary outcome is the Patient Specific Functional Scale (PSFS). Secondary outcomes include comfort (SCS), satisfaction (OPUS), psychosocial adjustment (TAPES-R), mobility (PLUS-M), prosthesis utility (PEQ-U), and the proportion of patients electing to keep the AS at study completion.
Read the detailed description
Background. Lower-limb amputation affects more than 7,500 people annually in France, with approximately 50% at the transtibial level. The socket is the critical interface between the residual limb and the prosthesis, transmitting mechanical forces while needing to remain comfortable. Currently, only RS (carbon or resin) are listed on the French reimbursable products list (LPPR) for transtibial amputation. Documented limitations of rigid sockets include restricted knee flexion, walking discomfort in challenging environments, donning difficulties, and suboptimal pressure distribution that does not adapt to residual-limb volume changes.
Investigational device. The AS follows the same molding and shaping principles as the standard RS but differs in two manufacturing steps: (1) carbon fibers are placed only on lateral, postero-inferior, and inferior areas to provide structural rigidity; (2) stratification uses urethane resin (ProtheFLEX®, already used in medical-device manufacturing) instead of epoxy or acrylic resin, creating soft zones in regions typically rigid in conventional sockets.
Comparator. Both sockets are manufactured from the same plaster mold to ensure strictly identical internal geometry. Only the material structure (carbon/urethane distribution) differs; all other prosthetic components (intermediate piece, prosthetic foot) are identical.
Design rationale. A double-blind design is not feasible because participants can perceive differences in socket rigidity and prosthesis weight. The crossover design controls for between-subject variability and order effects.
Sample size. Based on the preliminary study (Patient Specific Functional Scale (PSFS) standard deviation 1.74), to detect a difference of 1.3 points (the PSFS MDC₉₀ for 3 items) with 80% power and α=0.05, 19 participants are required. 25 will be enrolled to account for dropouts and to provide a more representative sample for secondary endpoints.
Visits. Four study visits over approximately 14-21 weeks per participant: inclusion (V0), evaluation after first socket period (V1), evaluation after second socket period (V2), and an optional follow-up visit (V3) one month later if the participant elects to keep the AS.
- Being tested
- Access Socket (AS), Rigid Socket (RS)
- Keywords
- Transtibial prosthesis, Prosthetic socket, Flexible socket, Access Socket, Comfort, Quality of life, Rehabilitation, cross over trial, Patient Specific Scale
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Access Socket (AS)Device
Hybrid prosthetic socket combining a rigid carbon-fiber structure in load-bearing areas (lateral, postero-inferior, inferior) with flexible urethane-resin (ProtheFLEX®) zones in regions typically rigid in conventional sockets. Manufactured from the same plaster mold as the rigid socket to ensure identical internal geometry.
Rigid Socket (RS)Device
Conventional definitive carbon-fiber rigid socket, currently the only socket type reimbursed in France for transtibial amputation (LPPR-listed). Standard of care comparator.
| Study group | Role | What they receive |
|---|---|---|
| Group 1 (RS -> AS) | Active comparator | Participants wear their standard rigid socket (RS) for 4 weeks, complete evaluation, then switch to the Access Socket (AS) for 1-2 weeks of adaptation followed by 4 weeks of wear, with a second evaluation. Receives: Device: Access Socket (AS); Device: Rigid Socket (RS) |
| Group 2 (AS -> RS) | Active comparator | Participants receive the Access Socket (AS) first, with 1-2 weeks of adaptation followed by 4 weeks of wear and evaluation. They then switch to the standard rigid socket (RS) for 1-2 weeks of adaptation and 4 weeks of wear, with a second evaluation. Receives: Device: Access Socket (AS); Device: Rigid Socket (RS) |
What is being measured
The primary outcome is the main question the study is designed to answer.
Patient Specific Functional Scale (PSFS) score
Patient-centered self-report tool. The patient identifies 3-5 specific activities they have difficulty performing, then rates their ability on a 0-10 scale (0 = unable to perform, 10 = able to perform at pre-injury level). The final score is the mean of the ratings
Measured: One time at the end of each 4-week wear period (V1, V2 and V3)
Secondary outcomes (5)
Socket Comfort Scale (SCS) score
0-10 numerical rating of socket comfort (0 = least comfortable imaginable, 10 = most comfortable imaginable)
Measured: One time at the end of each 4-week wear period (V1, V2 and V3)
Orthotics Prosthetics Users Survey (OPUS) score
Self-report instrument evaluating functional outcomes and quality of life specifically for orthosis and prosthesis users. Assesses lower-limb functional status, health-related quality of life, satisfaction with the device, and satisfaction with services. The higher the score, the more favorable the result for the device
Measured: One time at the end of each 4-week wear period (V1, V2 and V3)
Trinity Amputation and Prosthesis Experience Scale - Revised (TAPES-R) score
33-item multidimensional questionnaire evaluating psychosocial adjustment to amputation and prosthesis use, including general adjustment, social adjustment, activity restriction, and prosthesis satisfaction. The higher the global score, the more favorable the result for the device
Measured: One time at the end of each 4-week wear period (V1, V2 and V3)
Prosthesis Evaluation Questionnaire - Utility subscale (PEQ-U) score
The score is calculated as the mean of the 8 items in the subscale. Each item is rated on a Visual Analogue Scale (VAS) from 0 to 100. The total score ranges from 0 to 100, where higher scores indicate a better outcome (greater satisfaction and prosthesis utility)
Measured: One time at the end of each 4-week wear period (V1, V2 and V3)
Proportion of participants electing to keep the Access Socket at study completion
Percentage of participants who choose the AS over the RS at the end of the study, reported with 95% confidence interval. Participants are not informed of this option until the end of the study to avoid judgment bias
Measured: Through study completion, an average of 10 weeks
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted18 May 2026
- Study start27 Apr 2026
- Primary completion27 Apr 2027 (estimated)
- Study completion30 Oct 2027 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Transtibial AmputationStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Crossover
- Model description
- Open-label, two-arm randomized crossover trial. Each participant wears both sockets sequentially in a randomized order. Each socket period includes a 1-2 week adaptation/adjustment phase followed by a 4-week wear period before evaluation.
- Masking
- None (open label)
- Enrolment
- 25 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Union de Gestion des Etablissements des Caisses d'Assurance Maladie - Nord Est
- Sponsor type
- University, hospital or other
- Collaborators
- Institution Nationale des Invalides, Hôpital Filieris de Freyming-Merlebach, Ortho Access, H20 Orthopedie, Otto Bock France SNC, Hôpital d'Instruction des armées Percy, Clinical Investigation Center - University Hospital Grenoble
- Responsible party
- Sponsor
- Investigators
- Isabelle Loiret, MD, Principal investigator, Institut Régional de Médecine Physique et de Réadaptation (IRR), Nancy, France
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07592325
- Sponsor's protocol ID
- 2026-A00019-42
- Acronym
- AS-TT
- Status last verified
- May 2026
- First submitted
- 5 May 2026
- Last updated
- 18 May 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No: : Individual participant data will not be shared. Aggregated study results will be published in scientific journals and a summary report will be transmitted to the CPP within 12 months of study completion