Device for imparting continuous passive motion to leg joints

Abstract

An apparatus having an elongated base from the proximal end of which a reclining patient's leg is extended to an elevated connection of the foot with a foot rest. Mechanism is provided for moving the foot rest so that the hip and knee may be mobilized to the exclusion of the ankle or vice-versa, by applying forces similar to those applied manually by a physiotherapist. This mechanism translates the longitudinal reciprocal stroke of a motor driven carriage into a combination longitudinal and arcuate motion of the foot rest. The foot rest is mounted on the upper end of an actuating arm whose lower end has a pivotal connection with a carriage movable along the base, in linear strokes, toward and from the proximal end. A control beam has a pivotal connection to the upper end of the arm and is provided with a proximally extending frame for connection to the base to hold the beam in a position spaced from the proximal end with the arm held for pivotal movement relative to the upper end of the beam whereby the ankle only is mobilized with the knee and hip joints immobile. A catch mechanism is provided for locking the beam against pivotal movement relative to the arm whereby with the supporting frame free of the base and adjacent the leg, the patient's hip and knee joints are mobilized, with the ankle joint immobile. A reversible motor moves the carriage back and forth in linear strokes. A potentiometer measures the angular position of the actuating arm and is connected to the motor control whereby the length of the strokes is governed by setting limits on the angular movement of the actuating arm, regardless of the position of the carriage on the base. Mounting legs extend from the base, to mount the machine from fixed objects, through terminal clamps of unique construction.