GB1382430A - Artificial legs - Google Patents

Abstract

1382430 Artificial legs K A FRIBERG AB 30 Dec 1971 [7 Jan 1971] 60834/71 Heading A5R An above-knee leg prosthesis comprises a thigh section 1; a shank section 3 pivotally attached to the thigh section 1 by a knee-joint shaft 2; an ankle section 4 attached to the shank section 3 and including a plate 31; a foot 5 having a plate 40 which is pivotally attached to the forward end of the ankle plate 31 by a horizontal shaft 30, the shaft 30 being positioned in front of the weight-supporting line 57; a spring 51 mounted behind the horizontal shaft 30 and between the plates 40, 31 for biasing them apart; and a mechanism 8 for controlling flexure of the knee joint. The angle between the plates 40, 31 is limited by the head 49 of a bolt 45 attached to the ankle plate 31 and extending down through a hole in the foot plate 40. A washer 50 of rubber or other resilient material is positioned between the foot plate 40 and the bolt head 49 and a similar washer 48 is between the plates 40, 31. The ankle plate 31 has a vertical bore 54 with a shoulder 53 at its upper end. Inside the bore 54 are the spring 51, and a chuck 28 which is below the spring 51 and is forced thereby against the foot plate 40. The chuck 28 is connected, through a wire (26), lever (21), Fig. 2 (not shown) and a wire 23, to the joint-control mechanism 8. The mechanism 8 may, as shown, consist of two intercommunicating hydraulic piston-and-cylinder devices 9, 10. When the prosthesis is loaded the plates 40, 31 are forced together, and the chuck 28 is moved upwardly in the bore 54. This causes locking of the mechanism 8 by closing of the intercommunication between cylinders 9, 10. In the loaded position, Fig. 3, the knee-joint shaft 2 is behind the weightsupporting line 57. When the load is removed, but the foot 5 is still in contact with the ground, the spring 51 causes the shank section 3 to pivot forwardly about the shaft 30, thus moving the knee-joint shaft 2 is front of the weight-supporting line 57, Fig. 4 (not shown). Simultaneously the mechanism 8 is unlocked. When the foot 5 is lifted from the floor, the spring 51 causes the toe to pivot upwards. The foot plate 40 may be attached to the foot 5 by a universal joint 41 in a pad 43 of compressible material. In an alternative embodiment, Fig. 13 (not shown) the bolt (45) and washer (50) are replaced by a bracket (65) attached to the rear of the ankle plate 31 and having a portion (68) turned inwardly under the foot plate 40. with an elastic member (69) in the gap (67) therebetween.