[Preliminary experiences on triscaphoid arthrodesis]

Abstract

The authors report their experience of 5 patients (4 males, 1 female) with a mean age of 36.4 years (min 25 years, max 45 years), undergoing triscaphoid arthrodesis between May 1989 and August 1993. The patients suffered from rotatory dislocation of the scaphoid (1 case) and stage 3A of Kienboeck's disease according to Lichtman's classification (4 cases). The paper describes the surgical technique used for partial arthrodesis of the wrist performed using plexual anesthesia. A dorsal access route is used through a curved longitudinal skin incision corresponding to the anatomical site of the scaphoid. The skin flaps are then peeled back revealing the surface veins and sensitive branches of the radial nerve which are isolated and conserved. Having cut through the retinaculum of the extensors, the extensor tendons are spread so as to reach the joint capsule which is sectioned crosswise. After the bone to be fused have been exposed, the cartilage is removed from the joint faces between the scaphoid, trapezium and trapezoid and, using a osteotribe, the subchondral bone is removed to reveal the spongy bone, leaving a space of approximately 6 mm between the spongy surface of the bones to be fused. Arthodesis is stabilised using Kirschner wires or metal minicambres enclosing scaphoid, trapezium and trapezoid. Spongy tissue is taken from the distal radial head and used as a graft to fill the spaces created between them which will consolidate over time. The wrist is immobilised in a plaster cast for 8 weeks before starting functional rehabilitation. Patients were checked both clinically and radiographically with a mean follow-up of 36.4 months (min 25, max 50 months). Using the assessment criteria proposed by Minami et al. excellent results were obtained in 4 patients (80%) with the disappearance of painful symptoms, joint excursion 50% greater than the normal wrist, and hand grip 70% greater than in the controlateral hand. There was good radiographical consolidation of the arthrodesis. Poor results were only recorded in one case (20%) with persisting pain and functional impotent. Radio-scaphoid arthrosis was observed radiographically consequent to hypercorrection of the scaphoid with a radio-scaphoid angle of less than 45 degrees. The authors underline the technical difficulty of this arthrodesis characterised by reduction of the scaphoid in a correct position in which the radio-scaphoid angle must be 45 degrees when measured from a lateral position. Lastly, the authors conclude that this from of arthrodesis may be used with good results to treat wrist pathologies such as rotatory scaphoid dislocation, triscaphoid arthrosis and Kien-boeck's disease at stage 3A according to Lichtman. They also affirm that arthrodesis limited to the wrist is preferable to total arthrodesis because it enables some joint movement to be conserved which is important for hand function.