NCT Number: NCT07592325
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.
Interested in participating?
Request Info18 year and older
All sexes
Interventional
Not applicable
Hôpital National d'Instruction des Armées (HNIA) Percy, Clamart, France
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.
Healthy volunteers accepted: No
Only the study team can determine whether someone qualifies for participation.
Inclusion criteria
Exclusion criteria
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.
Conventional definitive carbon-fiber rigid socket, currently the only socket type reimbursed in France for transtibial amputation (LPPR-listed). Standard of care comparator.
Time frame: One time at the end of each 4-week wear period (V1, V2 and V3)
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
Time frame: One time at the end of each 4-week wear period (V1, V2 and V3)
0-10 numerical rating of socket comfort (0 = least comfortable imaginable, 10 = most comfortable imaginable)
Time frame: One time at the end of each 4-week wear period (V1, V2 and V3)
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
Time frame: One time at the end of each 4-week wear period (V1, V2 and V3)
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
Time frame: One time at the end of each 4-week wear period (V1, V2 and V3)
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)
Time frame: Through study completion, an average of 10 weeks
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
Contact information is provided by the study sponsor or research team.
Isabelle Loiret, MD
CONTACT
Jonathan Pierret, PhD
CONTACT
Union de Gestion des Etablissements des Caisses d'Assurance Maladie - Nord Est
Other
Acronym: AS-TT
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View the official ClinicalTrials.gov record (opens in a new tab)This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.
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