1. Prehension is a complex mechanism for which both movement and sensation are required. 2. Two basic grips are considered: the digital pinch and palmar grasp, which are simpler expressions of the precision grip and the power grip. For the digital pinch the minimum requirement is a thumb or a reconstructed thumb, and a finger to which it can oppose. For palmar grasp mobile fingers are necessary so that they can wrap round the object grasped. 3. The restoration of prehension is considered under the following headings: mutilation of the fingers; mutilation of the thumb; and mutilation of both together. 4. The various methods of reconstruction are described that are appropriate to each type of mutilation, so as to provide restoration of length, mobility and sensation. 5. The indications for the various main methods to compensate for loss of the thumb are discussed. These methods include pollicisation and osteoplastic repair with neurovascular island flap.
1 . The extensor assembly of the fingers consists of the central tendon joined by three pairs of components: 2. The retinacular ligaments are relaxed in full extension of the proximal interphalangeal joints and are, in this position, unable to extend the distal joints fully. This is because the interphalangeal joint surfaces are eccentric. 3. The pull of the wing tendons alters the shape of the extensor expansion and transfers the pull of the long extensor tendon from the base of the middle phalanx to the base of the distal phalanx, thus enabling full extension of the distal joint to be powerfully achieved. 4. The action of the lumbrical muscle, as an extensor of the interphalangeal joint, is demonstrated by a diagram showing its site and length in the various positions of the finger, calculated from the known excursions of the tendons. This is consistent with the observations on action potentials. 5. The phalangeal tendons of the dorsal interossei have a bifid insertion, Finally an explanation of the deformity of clawing in ulnar palsy is given.
