Patent Application
20230329884
This application claims priority of Taiwanese Patent Application No. 111114521, filed on Apr. 15, 2022.
The disclosure relates to a prosthetic knee joint, and more particularly to a prosthetic knee joint with a biasing unit providing a damping effect during walking.
A conventional prosthetic knee joint includes a lower leg connecting part and a thigh connecting part which is coupled to the lower leg connecting part through a linkage assembly with an anterior link and a posterior link connected between the lower leg connecting part and the thigh connecting part. The lower leg connecting part, the thigh connecting part, the anterior link and the posterior link are cooperatively formed as a four-bar linkage mechanism. The thigh connecting part is movable relative to the lower leg connecting part between a stance position and a knee bending position. However, the conventional prosthetic knee joint with such four-bar linkage mechanism provides insufficient damping against an impact generated as a result of contact with the ground during walking.
Therefore, an object of the disclosure is to provide a prosthetic knee joint that can alleviate at least one of the drawbacks of the prior art.
According to the disclosure, the prosthetic knee joint includes a lower leg connecting part, a thigh connecting part, a linkage assembly and a biasing unit. The lower leg connecting part has a first anterior link portion and a first posterior link portion. The first posterior link portion has a slidable pivot shaft which extends in a left-right direction. The thigh connecting part is disposed above the lower leg connecting part and has a second anterior link portion and a second posterior link portion. The linkage assembly is disposed between the lower leg connecting part and the thigh connecting part. The linkage assembly includes at least one anterior link which is pivotably connected between the first anterior link portion and the second anterior link portion, and a posterior link which is pivotably connected between the first posterior link portion and the second posterior link portion. The posterior link has a slotted pivot linkage which extends therethrough in the left-right direction for pivotally connecting and engaging with the slidable pivot shaft. The pivot linkage is elongated in an up-down direction to have an upper slot end section and a lower slot end section. The slidable pivot shaft is slidably and rotatably engaged in the pivot linkage such that, through pivoting of the linkage assembly, the thigh connecting part is movable relative to the lower leg connecting part between a stance position and a knee bending position, and such that the slidable pivot shaft is moved from the lower slot end section to the upper slot end section with an impact transmitted from the lower leg connecting part to cause a downward movement of the posterior link relative to the lower leg connecting part. The biasing unit abuts against the posterior link to urge movement of the thigh connecting part toward the stance position, and to bias upwardly the posterior link so as to urge the lower slot end section of the pivot linkage to engage with the slidable pivot shaft.
With the slidable engagement of the slidable pivot shaft with the pivot linkage, and the biasing unit biasing the posterior link upwardly and urging the pivot linkage to bring the lower slot end section to engage with the slidable pivot shaft, a damping effect is provided to reduce the impact when contacting with the ground. Also, an excess inflexion of the knee joint in the foot ground-contact phase is prevented for increased safety.
Other features and advantages of the disclosure will become apparent in the following detailed description of the embodiment with reference to the accompanying drawings, of which:
Referring to
The lower leg connecting part 1 substantially extends in an up-down direction (D1), and has a first anterior link portion 11 and a first posterior link portion 12 which are at an upper end thereof and opposite to each other in a front-rear direction (D2), and a lower leg connecting portion 13 which is at a lower end thereof for connecting a shin tube (not shown). The first posterior link portion 12 has a slidable pivot shaft 121 which extends in a left-right direction (D3).
The thigh connecting part 2 is disposed above the lower leg connecting part 1, and has a second anterior link portion 21 and a second posterior link portion 22 which are opposite to each other in the front-rear direction (D2), and a thigh connecting portion 23 which is at an upper end thereof for connecting a thigh socket (not shown).
The linkage assembly 3 is disposed between the lower leg connecting part 1 and the thigh connecting part 2. The linkage assembly 3 includes two anterior links 31 each of which is pivotably connected between the first anterior link portion 11 and the second anterior link portion 21, and a posterior link 32 which is pivotably connected between the first posterior link portion 12 and the second posterior link portion 22. The number of the anterior links 31 may be one or more than two. The posterior link 32 has a slotted pivot linkage 321 which extends therethrough in the left-right direction (D3) for pivotally connecting and engaging with the slidable pivot shaft 121. The pivot linkage 321 is elongated in the up-down direction (D1) to have an upper slot end section (321a) and a lower slot end section (321b). The slidable pivot shaft 121 is slidably and rotatably engaged in the pivot linkage 321. The posterior link 32 further has a cushion member (321c) disposed in the upper slot end section (321a) for the slidable pivot shaft 121 to abut thereagainst during the sliding movement of the slidable pivot shaft 121 along the pivot linkage 321. For example, the cushion member (321c) is made of polymeric material, such as foam material. Thus, when the posterior link 32 is moved downward to bring the pivot linkage 321 to move downward relative to the slidable pivot shaft 121 so as to cause the engagement of the slidable pivot shaft 121 with the upper slot end section (321a), the cushion member (321c) can provide a damping effect to the slidable pivot shaft 121. That is, the cushion member (321c) provides a damping effect when the slidable pivot shaft 121 slides along the pivot linkage 321 from the lower slot end section (321b) to the upper slot end section (321a).
Specifically, the slidable pivot shaft 121 is moved from the lower slot end section (321b) to the upper slot end section (321a) by a distance ranging from 5 mm to 7 mm. In this embodiment, the distance is 6 mm.
The biasing unit 4 abuts against the posterior link 32 to urge movement of the thigh connecting part 2 toward the stance position. The biasing unit 4 is attached to and abuts against a lower portion of the posterior link 32 at a torque application point 43 which is disposed anterior of the slidable pivot shaft 121. Specifically, the lower leg connecting part 1 has a central accommodation barrel 14 which has an upper opened end 142 and which extends in the up-down direction (D1) from the upper opened end 142 to terminate at a bottom barrel wall 143. The central accommodation barrel 14 defines an accommodation space 141 therein. The biasing unit 4 includes an abutting member 41 which is slidably received in the accommodation space 141 and which projects partially from the upper opened end 142 of the central accommodation barrel 14 to abut against the posterior link 32, and a biasing member 42 which is disposed in the accommodation space 141 and interposed between the bottom barrel wall 143 and the abutting member 41. The abutting member 41 has the torque application point 43 abutting against the lower portion of the posterior link 32. The biasing member 42 may be a compression spring.
With reference to
With reference to
Furthermore, when the upper slot end section (321a) of the pivot linkage 321 is moved to engage with the slidable pivot shaft 121 during the pivoting of the linkage assembly 3, the angular position of the posterior link 32 relative to the anterior links 31 has been changed such that, after the thigh connecting part 2 is moved through the pivoting of the linkage assembly 3 relative to the lower leg connecting part 1 by a predetermined amount of movement, the pivoting movement of the linkage assembly 3 is resisted and the rearward tilting movement of the thigh connecting part 2 relative to the lower leg connecting part 1 is also resisted. The thigh socket is hence kept in a predetermined angular position relative to the shin tube. Thus, an excess inflexion of the thigh socket relative to the shin tube is prevented for increased safety. Also, the predetermined amount of movement and the predetermined position (i.e., a maximum knee angle) are adjustable as required. For example, the predetermined amount and the predetermined angular position can be adjusted by varying the structure of the linkage assembly 3 (e.g., length, initial angle, etc.) and/or by varying the pivot axes between the linkage assembly 3 and one of the lower leg connecting part 1 and the thigh connecting part 2.
As illustrated, with the slidable engagement of the slidable pivot shaft 121 of the first posterior link portion 12 with the pivot linkage 321 of the posterior link 32, and the biasing unit 4 biasing the posterior link 32 upwardly and urging the pivot linkage 321 to bring the lower slot end section (321b) to engage with the slidable pivot shaft 121, a damping effect is provided to reduce the impact when contacting with the ground. Also, an excess inflexion of the knee joint in the foot ground-contact phase is prevented for increased safety.
While the disclosure has been described in connection with what is considered the exemplary embodiment, it is understood that this disclosure is not limited to the disclosed embodiment but is intended to cover various arrangements included within the spirit and scope of the broadest interpretation so as to encompass all such modifications and equivalent arrangements.
| Number | Date | Country | Kind |
|---|---|---|---|
| 111114521 | Apr 2022 | TW | national |
