Knee joint mechanism for knee disarticulation prosthesis
First Claim
1. In a knee joint for knee disarticulation prosthesis rotatable between flexed and extended positions, and comprising a four bar linkage consisting of a thigh link and a shin link pivotally connected to an anterior link and a posterior link to define a four bar linkage, the improvement comprising:
- (a) the thigh link forming a negative angle with respect to a horizontal plane when the knee joint is in an extended position;
(b) the shin link being positioned substantially along the horizontal plane when the knee joint is in the extended position,the length of said shin link and said anterior link and posterior link, as well as the angle which the thigh link forms with respect to the horizontal plane, are selected to maximize a height, YIC, of an instant center of the knee joint for knee disarticulation prosthesis above the shin link at 90°
flexion according to the equation;
##EQU4## where L1 is the length of the shin link, θ
2 is the angle made between the posterior link and the shin link, and θ
4 is the angle made between the anterior link and the shin link.
0 Assignments
0 Petitions
Accused Products
Abstract
An improved four-bar knee joint mechanism for use in knee disarticulation prosthesis is shown, including a coupler link forming a negative angle with the horizontal when said knee joint mechanism is in its stance position, an anterior link, a fixed link in a horizontal position when said knee joint is in the extended or stance position, and a posterior link, the dimensions of the links and the angle the coupler link makes with the horizontal being chosen to optimize the instant center of the mechanism.
165 Citations
24 Claims
-
1. In a knee joint for knee disarticulation prosthesis rotatable between flexed and extended positions, and comprising a four bar linkage consisting of a thigh link and a shin link pivotally connected to an anterior link and a posterior link to define a four bar linkage, the improvement comprising:
-
(a) the thigh link forming a negative angle with respect to a horizontal plane when the knee joint is in an extended position; (b) the shin link being positioned substantially along the horizontal plane when the knee joint is in the extended position, the length of said shin link and said anterior link and posterior link, as well as the angle which the thigh link forms with respect to the horizontal plane, are selected to maximize a height, YIC, of an instant center of the knee joint for knee disarticulation prosthesis above the shin link at 90°
flexion according to the equation;
##EQU4## where L1 is the length of the shin link, θ
2 is the angle made between the posterior link and the shin link, and θ
4 is the angle made between the anterior link and the shin link. - View Dependent Claims (2, 3, 4, 5)
-
-
6. A four-bar knee joint mechanism including:
-
(a) a coupler link forming a negative angle of about 25°
with the horizontal when said knee joint mechanism is in its stance position, said coupler link being no less than substantially one inch in length;(b) an anterior link of approximately 3.75 inches in length between centers; (c) a fixed link of approximately 2.50 inches in length between centers and in a horizontal position when said knee joint mechanism is in the stance position; and (d) a posterior link of approximately 3.575 inches in length between centers. - View Dependent Claims (7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
-
-
18. A four-bar knee joint mechanism for knee disarticulation prosthesis, comprising:
-
a pair of anterior links; a pair of posterior links; a coupler link being pivotally connected to each pair of said anterior links and said posterior links; a fixed link being pivotally connected to each pair of said anterior links and said posterior links; a ratio of a length of said coupler link, a length of said fixed link, a length of each of said pair of anterior links, and a length of each of said pair of posterior links is 1;
2.5;
3.75;
3.575. - View Dependent Claims (19, 20, 21, 22, 23, 24)
-
Specification