System for controlling artificial knee joint action in an above knee prosthesis

• US 5,571,205 A
• Filed: 11/18/1994
• Issued: 11/05/1996
• Est. Priority Date: 12/05/1991
• Status: Expired due to Term

• Current Assignee: Otto Bock HealthCare GmbH (OTTO BOCK Holding GmbH & Company KG)
• Original Assignee: Kelvin B. James
• Inventors: James, Kelvin B.
• Primary Examiner(s): Willse, David H.
• Application Number:
  US08/341,127
• Time in Patent Office: 718 Days
• Field of Search: 623/24, 623/43, 623/44, 623/26
• US Class Current: 623/24
• CPC Class Codes: A61F 2/64 Knee joints
• CPC Class Codes: A61F 2/70 electrical
• CPC Class Codes: A61F 2/74 fluid , i.e. hydraulic or pneumatic
• CPC Class Codes: A61F 2/748 Valve systems
• CPC Class Codes: A61F 2002/5003 having damping means, e.g. shock absorbers
• CPC Class Codes: A61F 2002/704 computer-controlled, e.g. robotic control
• CPC Class Codes: A61F 2002/7615 Measuring means
• CPC Class Codes: A61F 2002/7635 for measuring force, pressure or mechanical tension
• CPC Class Codes: B62D 57/00 Vehicles characterised by having other propulsion or other ground- engaging means than wheels or endless track, alone or in addition to wheels or endless track sledges B62B; motor sledges B62M

Abstract

This invention relates to an above knee prosthesis which employs a hydraulic damper to passively regulate the angular velocity or rotation of the artificial knee joint. A programmed microprocessor recognizes common gait patterns from information received from bending moment strain and knee angle sensors on the prosthesis. The microprocessor, under the control of a rule-based program, reacts at various transition points in the gait by activating a motor which in turn adjusts a valve assembly in the damper. The valve assembly is capable of variably and separately damping the knee joint motion in each of flexion and extension at the same time. Gait is improved because of the improved extent of control of knee action. In addition, distinct routines such as stair descending and sitting down can also be practised.

Claims

1. A method for controlling rotation of the knee joint of an above knee prosthesis (AKP) in flexion and extension, said AKP in use having a predictable pattern of swing and stance phases states having durations, comprising:

(a) circulating fluid with pumping means driven by the AKP through a first passageway in the course of flexion and through a second passageway in the course of extension;

(b) continuously measuring, throughout the course of AKP movement, at least two AKP characteristics which vary with the activity of the AKP;

(c) using the measurements to continuously establish the state of the AKP throughout the course of its movement, having reference to the predictable patterns and durations of AKP movements; and

(d) separately varying the flow capacity of the first passageway at pre-determined transition points in the course of AKP movement and separately varying the flow capacity of the second passageway at pre-determined transition points in the course of AKP movement, to separately and variably damp knee rotation in each of flexion and extension.

2. The method as set forth in claim 1 wherein:

the AKP characteristics measured are knee angle and bending moment strain.

3. The method as set forth in claim 1 wherein:

the fluid is liquid hydraulic fluid.

4. A method for controlling rotation of the knee joint of an above knee prosthesis (AKP) in each of flexion and extension, said AKP in use having a predictable pattern of swing and stance phase states having durations, using hydraulic fluid pumping means, driven by the AKP, for circulating fluid, two passageways, each connected with the pumping means, for circulation of fluid therethrough, means for controlling the entry of pumped fluid into the first passageway so that it only enters when the AKP Is experiencing flexion, means for controlling the entry of pumped fluid into the second passageway so that it only enters when the AKP is experiencing extension, first variable valve means associated with the first passageway for restricting the flow capacity thereof, second variable valve means associated with the second passageway for restricting the flow capacity thereof, actuating means for adjusting each variable valve means, sensor means for measuring, during the course of AKP movement, at least two AKP characteristics which vary with the activity of the AKP, computer means connected with the sensor means and the actuating means and programmed for establishing the state of the AKP using the sensor means measurements and for controlling the actuating means to adjust the first and second variable valve means to separately vary the flow capacity of each passageway, comprising the steps of:

(a) circulating liquid hydraulic fluid with the pumping means through the first passageway in the course of flexion and through the second passageway in the course of extension;

(b) using the sensor means to continuously measure, throughout the course of AKP movement, at least two AKP characteristics which vary with the activity of the AKP;

(c) transmitting the sensor means measurements to the computer means and using the measurements to continuously establish the state of the AKP throughout the course of its movement, having reference to the predictable patterns and durations of AKP movements; and

(d) utilizing the computer means to separately adjust the first and second variable valve means to separately vary the flow capacity of the first passageway at pre-determined transition points in the course of AKP movement and separately vary the flow capacity of the second passageway at pre-determined transition points in the course of AKP movement, to separately and variably damp knee rotation in each of flexion and extension.

5. The method as set forth in claim 4 wherein:

the AKP characteristics measured are knee angle and bending moment strain.