Externally powered joint prosthesis

Abstract

Abstract A JOINT PROSTHESIS IS DISCLOSED IN AN ARM EMBODIMENT HAVING A FIRST UNIT PROVIDING A STUMP-RECEIVING SOCKET WITH A DISTAL SUPPORT AND A SECOND UNIT TO REPLACE THE MISSING MEMBER AND INCLUDING FRAMEWORK WITH A JOINT-ESTABLISHING PIVOT CONNECTING THE FRAMEWORK TO THE SUPPORT. JOINT FLEXING MEANS CARRIED BY THE FRAMEWORK INCLUDES A DIRECT CURRENT, PERMANENT MAGNET MOTOR AND A BALL SCREW DRIVEN THEREBY AND RECEIVED BY A BALL NUT PIVOTALLY MOUNTED ON THE SUPPORT BELOW THE JOINT PIVOT. THE CONTROL CIRCUIT FOR THE MOTOR IS CONNECTABLE TO A POWER SOURCE AND DISCLOSED AS UTILIZING BIOELECTRIC SIGNALS, ELECTROMYOGRAPHIC SIGNALS DERIVED FROM TWO MUSCELS BEING ONE BASIS OF CONTROL WITH EACH MUSCLE NORMALLY MOVING THE NOW MISSING MEMBER IN A DIRECTION OPPOSITE TO THAT OF THE OTHER. THE CONTROL CIRCUIT ALSO PROVIDES THAT THE SIGNALS FROM EACH MUSCLE ARE RECTIFIED WITH OPPOSITE SIGNES ADDED AND COMBINED SO THAT THE RESULTANT IN A SIGNAL PROPORTIONAL TO THE DIFFERENCE BETWEEN THE MUSCLE TENSIONS AND PROVIDES A BASIS FOR MOTOR REVERSAL. THE PROSTHESIS INCLUDES ONE OR MORE OF SUCH FEATURES AS A FIXED MOUNTING OF THE MOTOR AND BRAKE IN THE FRAMEWORK AND THE PIVOTAL ATTACHMENT OF THE DISTAL END OF THE BALL SCREW THERETO WITH A FLEXIBLE, ENDLESS DRIVE BETWEEN THE MOTOR SHAFT AND BALL SCREW, A BRAKE THAT IS ENGAGED WHENEVER THE MOTOR SPEED IS ZERO, A FORCE FEEDBACK MEASURING STRAIN TRANSMITTED THROUGH THE BALL SCREW, A VELOCITY FEEDBACK DERIVED FROM THE FLEXING OF THE PROSTHETIC JOINT, AND A CONTROL WHICH OPENS THE MOTOR AND BRAKE CIRCUITS AS LONG AS MUSCLE TENSION AND TORQUE ARE IN BALANCE.

Inventors

• 👤 Cord W Ohlenbusch
• 👤 David B Russell

Bibliographic Details