[Principles of palliative motor surgery of paralysis of the hand]

Abstract

The purpose of surgical restoration of the paralysed hand is to use or to reconstruct the physiological tenodesis effects which are linked on to flexion-extension motions of the wrist. Active movements of interphalangeal (IP) flexion and metacarpo-phalangeal (MP) extension of the fingers are made by extrinsic muscles coming from the forearm. The intrinsic muscles of the fingers produce MP flexion and IP extension. A claw deformity occurs when they are completely paralysed in a finger whose joints are flexible, and whose extrinsic muscles remains functional or are restored. When Bouvier's maneuver is positive, the claw is said simple, and its treatment is either MP capsuloplasty when there is no motors, or an active palliative procedure with proximal (or MP) effect when motors exist: lasso and/or direct interosseous activation. Indications of the classical active palliative procedures with distal (or IP) effect remain rare, only in a few complicated claw deformities. Circumduction of the thumb may be decomposed into three elementary movements: reposition, antepulsion, and adduction, which are respectively controlled by the radial, median, and ulnar nerves. Each of these movements may be restored by a specific tendinous transfer. In the total paralysis of the thumb as we observe in high tetraplegia, a key-grip may be restored by joint stabilization of the thumb, associated with activation of the Flexor Pollicis Longus and Extensor Pollicis Longus by means of tenodesis or tendinous transfers.