US-20260124050-A1 - SELF-ADJUSTING SOCKET FOR LOWER LIMB PROSTHESIS

Abstract

The present disclosure describes self-adjusting sockets for lower limb prostheses in which each step transmits motion to a resilient resistive element coupled to an actuator configured to cycle between a rest position and an actuated position. The resistive element can transmit the motion to the actuator to cycle the actuator. Each cycle of the actuator acts through a mechanical linkage to tighten the socket around the residuum, until a desired threshold tightness on the residuum is reached. After the threshold tightness is reached, the resistive element yields and absorbs the motion rather than transmitting the motion, so that the actuator ceases to cycle on each step, preventing further tightening beyond the threshold.

Inventors

• Sydney Motz Robinson
• Oleksiy Zaika
• Sajed Cela

Assignees

• VESSL PROSTHETICS INC.

Dates

Publication Date

20260507

Application Date

20251230

Claims (20)

1. 1 . A socket adjustment mechanism for a lower limb prosthesis, comprising: an actuator enclosure connectable to a receptacle body having a residuum receptacle; at least one actuator disposed within the actuator enclosure and connectable to a residuum retention mechanism associated with the residuum through a respective mechanical linkage, the at least one actuator configured to reciprocally cycle between a rest position and an actuated position and to act through the respective mechanical linkage to incrementally tighten the retention mechanism against the residuum on each movement of the at least one actuator into the actuated position and leave the retention mechanism further incrementally tightened upon each return of the actuator to the rest position; a releasable locking mechanism carried by the actuator enclosure and configured to maintain tightness of the retention mechanism against the residuum after each cycle of the at least one actuator; the actuator enclosure configured so that each step transmits motion to a respective resilient resistive element coupled to a respective one of the at least one actuator, wherein: when a tightness of the retention mechanism is below a threshold, each step transmits motion across the respective resistive element to the respective actuator to cycle the respective actuator to further tighten the retention mechanism; and when the tightness of the retention mechanism has reached the threshold, on each further step the respective resistive element yields to absorb the motion, so that the respective actuator fails to cycle on each further step, inhibiting further tightening of the retention mechanism beyond the threshold.
2. 2 . The socket adjustment mechanism of claim 1 , wherein the at least one actuator is a single actuator.
3. 3 . The socket adjustment mechanism of claim 1 , further comprising a manual tightening mechanism for tightening the retention mechanism.
4. 4 . The socket adjustment mechanism of claim 1 , further comprising: a housing comprising the residuum receptacle; and the retention mechanism; wherein the retention mechanism is carried by the housing and is configured for retaining a residuum within the residuum receptacle; wherein: the actuator enclosure is coupled to the residuum receptacle via the housing; and the at least one actuator is coupled to the retention mechanism through the respective mechanical linkage.
5. 5 . The socket adjustment mechanism of claim 4 , wherein: the retention mechanism comprises at least one panel movably carried by the housing; the at least one panel being movable inwardly and outwardly relative to the residuum receptacle; the at least one actuator is configured to act through the respective mechanical linkage to incrementally move the at least one panel inwardly to tighten the at least one panel against the residuum on each cycle of the at least one actuator.
6. 6 . The socket adjustment mechanism of claim 5 , wherein the at least one panel comprises a plurality of panels arranged circumferentially about the residuum receptacle.
7. 7 . The socket adjustment mechanism of claim 6 , where the panels are disposed in respective openings so as to be inwardly and outwardly displaceable relative to the housing.
8. 8 . The socket adjustment mechanism of claim 7 , wherein: the mechanical linkage comprises at least one cable coupled to at least one of the panels; each respective actuator is configured to incrementally increase tension in a respective one of the at least one cable on each cycle of the respective actuator; and incrementally increasing the tension on the respective cable moves the respective panels inwardly relative to the residuum receptacle.
9. 9 . The socket adjustment mechanism of claim 8 , wherein: the actuator enclosure carries a movable platform; the platform is reciprocally movable relative to the actuator enclosure between a distal position and a proximal position; the platform is biased into the distal position; the at least one actuator is carried by the actuator enclosure between the residuum receptacle and the platform; the respective resistive element is trapped between the platform and the respective actuator whereby movement of the platform toward the proximal position pushes the resistive element toward the respective actuator; wherein reciprocal movement of the platform into the proximal position and back to the distal position cycles the respective actuator only where a resistance to compression of the respective resistive element exceeds a resistance to movement from the tension in the respective cable so that the respective resistive element transmits the movement of the platform to the respective actuator instead of yielding to the movement of the platform.
10. 10 . The socket adjustment mechanism of claim 9 , wherein: each actuator comprises a rocker coupled to a respective spool; each cycle of the rocker indexes the spool to wind the respective cable onto the spool to incrementally increase the tension in the respective cable.
11. 11 . The socket adjustment mechanism of claim 10 , wherein: each rocker comprises a respective outwardly extending actuator arm that acts as a lever to pivot the rocker; and where the resistance to compression of the respective resistive element exceeds a resistance to movement from the tension in the cable, the resistive element transmits the movement of the platform into the proximal position to the actuator arm to pivot the rocker and thereby index the spool.
12. 12 . The socket adjustment mechanism of claim 11 , wherein: a linearly movable cam is interposed between the resistive element and the rocker; each actuator arm is a cam follower received in a cam slot in the cam, whereby linear movement of the cam drives rotary movement of the rocker.
13. 13 . The socket adjustment mechanism of claim 11 , wherein the at least one resistive element is at least one spring.
14. 14 . The socket adjustment mechanism of claim 1 , wherein the at least one resistive element is at least one spring.
15. 15 . A method for securing a residuum in a socket of a lower limb prosthesis, the method comprising: transmitting motion from steps taken with the lower limb prosthesis across a resilient resistive element to an actuator to cycle the actuator between a rest position and an actuated position, wherein each cycle of the actuator incrementally tightens a retention mechanism against the residuum, until a tightness threshold of the retention mechanism is reached; and after the tightness threshold is reached, transmitting motion from further steps taken with the lower limb prosthesis into the resistive element wherein the resistive element yields and absorbs the motion so that the actuator fails to cycle on each further step, inhibiting further tightening of the retention mechanism beyond the threshold.
16. 16 . The method of claim 15 , wherein: each cycle of the actuator incrementally winds a cable around a spool to increase tension in the cable; the cable is coupled to the retention mechanism and increasing the tension in the cable tightens the retention mechanism.
17. 17 . The method of claim 16 , wherein increasing the tension in the cable tightens the retention mechanism by forcing a panel inwardly against the residuum.
18. 18 . The method of claim 15 , wherein the resistive element is a spring.
19. 19 . A method for tightening a panel in a receptacle for a residuum, the method comprising: applying incremental tension across the panel to move the panel inwardly relative to the receptacle, wherein: the incremental tension is applied by transmission of movement of an end effector of a lower limb prosthesis toward the residuum through a mechanical interface to a tensioner; and the movement is transmitted to the tensioner only when a resistance of the mechanical interface exceeds a current tension applied by the tensioner.
20. 20 . The method of claim 19 , wherein the resistance of the mechanical interface is provided by at least one spring.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a continuation-in-part of U.S. patent application Ser. No. 18/897,390 filed Sep. 26, 2024, which is a continuation-in-part of U.S. patent application Ser. No. 18/413,606 filed on Jan. 16, 2024. This application is also related to U.S. patent application Ser. No. 19/497,677 filed Dec. 29, 2025, which is a national stage application of Patent Cooperation Treaty application PCT/CA2025/050059 filed on Jan. 15, 2025. The aforementioned applications are hereby incorporated by reference in their entireties. TECHNICAL FIELD The present disclosure relates to sockets for lower limb prostheses, and more particularly to self-adjusting sockets for lower limb prostheses. BACKGROUND Amputation of a limb is tragic. Fortunately, medical technology has advanced considerably, and a wide range of prosthetic limbs are now available. A prosthetic limb typically consists of a prosthetic socket, an alignment device, one or more pylons, and an end effector. The prosthetic socket interfaces with the residual limb, or residuum, and connects it to the rest of the prosthetic limb. The alignment device typically maintains proper alignment between the socket and the rest of the prosthesis. The pylon(s) connect the socket and/or alignment device to the end effector. There may be a single pylon (e.g. for transtibial and transradial amputees) or multiple pylons (e.g. for transfemoral and transhumeral amputees) pylon(s) that connect the socket and/or alignment device to the end effector. The end effector typically replicates a foot or hand, depending on whether the prosthesis is for an upper limb (transhumeral, transradial) or lower limb (transfemoral, transtibial) amputee. In the case of a transfemoral amputee, the prosthetic limb also typically includes a knee joint. Arguably the most important component of a prosthetic limb is the prosthetic socket. It is the sole component connecting the residuum to the rest of the prosthetic limb. Effective interface (fit) between the socket and the residuum is crucial. A major complication in achieving an effective interface between the socket and the residuum is the fact that the size and shape of the residuum is not constant, but fluctuates over time. These fluctuations include short-term fluctuations and long-term fluctuations. Following amputation, the edema, or swelling, decreases and muscles in the residuum may atrophy from disuse, which leads to significant changes in the residuum's volume. These are examples of relatively long-term fluctuations, which may be accommodated straightforwardly, for example by the expedient of taking periodic measurements. In the acute phase following amputation (approximately two years post-amputation), an amputee typically requires several “check sockets” which are simple sockets that are used to check whether the fit is appropriate. Since the residuum loses significant volume from edema and muscle atrophy, amputees require a series of check sockets until their residuum volume has become sufficiently stable and does not decrease as significantly week-to-week. Unfortunately, change in the volume of the residuum is not only an acute issue following amputation, but often persists throughout an amputee's life. Moreover, short term changes in volume are common, and the volume of the residuum can change considerably over the course of a single day or even a few hours. Factors that can affect the volume of the residuum include, but are not limited to, exercise, diet, lifestyle, and other comorbidities, as well as weather. Since conventional prosthetic sockets are rigid and unchanging in size and shape, a change in the residuum's volume alters the socket fit, that is, the interface between the socket and residuum. Typically, an amputee will progressively lose volume over the long term, as a result of edema reduction and muscle loss, and the volume will oscillate over the short term. Activities of daily living, which include any kind of ambulation, can drive fluid out of the limb, reducing its volume. Prosthetic socks may be used to accommodate the longer-term decreases in volume - more socks and/or thicker socks may be used as residuum volume decreases over time. However, prosthetic socks are not well suited to accommodate the shorter-term fluctuations in residuum volume, as they would require the amputee to remove their prosthetic limb, add socks on top of their residuum, and then reattach the prosthetic limb. Adding or removing prosthetic socks is extremely disruptive to an amputee's activities of daily living; they must sit down to remove their prosthetic limb and rearrange or remove articles of clothing to access their residuum and add or remove prosthetic socks appropriately. They must also bring socks with them to every destination in case the need to add or remove prosthetic socks arises. Typically, amputees must add several prosthetic socks (in some cases, over 10) to properly account for the volume they l