The sauvé-kapandji procedure

Abstract

Arthrodesis is the most reliable and durable surgical procedure for the treatment of a joint disorder, and its only disadvantage is the loss of motion of the fused joint. The distal radioulnar joint can be arthrodesed, while forearm pronation and supination are maintained or even improved by creating a pseudoarthrosis of the ulna just proximal to the arthrodesis. This is known as the Sauvé-Kapandji (S-K) procedure. The Sauvé-Kapandji differs from the Darrach procedure in that it preserves ulnar support of the wrist, as the distal radioulnar ligaments and ulnocarpal ligaments are maintained. Aesthetic appearance is also superior after the S-K procedure, as the normal prominence of the ulnar head, most noticeable when the forearm is in pronation, is maintained. However, the S-K is not free of possible complications, such as nonunion or delayed union of the arthrodesis, fibrous or osseous union at the pseudoarthrosis, and painful instability at the proximal ulna stump. All of these complications can be prevented if a careful surgical technique is used.

Keywords: arthrodesis; distal radioulnar joint; triangular fibrocartilage; ulnocarpal impaction.

Fig. 1

(a) (Top) Cross-section anatomy of the DRUJ. The forearm is in pronation, and the ulnar head is covered by the DRUJ capsule and the extensor retinaculum. The fifth extensor compartment stabilizes the extensor digiti minimi tendon at the most ulnar border of the distal radius. The extensor carpi ulnaris (ECU) tendon is stabilized by its own sheath, separate from the extensor retinaculum, lateral to the styloid process of the ulna. (Bottom) Ulnar head after the extensor retinaculum has been ulnarly reflected and the dorsal radioulnar capsule removed. (b) Exposure of the extensor retinaculum. (c) Division of the fifth extensor compartment allows for identification and radial displacement of the extensor digiti minimi tendon. (d) Longitudinal division of the capsule exposes the head of the ulna. Joint synovitis, when present, should be removed as exposure will improve.

Fig. 2

(a) With the forearm in pronation, the joint cartilage and subchondral bone of the ulnar head facing the surgeon are removed, leaving a slightly convex surface of cancellous bone. (b) The ulnar head is perforated using a 3.2-mm drill bit, with the entrance at the center of the denuded ulnar head, which exits anteriorly to the styloid process and ECU sheath. The direction of the drill should be perpendicular to the long axes of the radius and ulna.

Fig. 3

The head of the ulna is osteotomized at the level of the neck and then displaced and rotated into supination, allowing visualization of the sigmoid notch of the radius. A segment of the proximal ulna is excised, and the joint cartilage and subchondral bone of the sigmoid notch of the radius are removed.

Fig. 4

Schematic drawing of the osteotomy of the head of the ulna done just at the proximal edge of the joint cartilage. Rotation of the head of the ulna into supination allows visualization of the sigmoid notch of the radius.

Fig. 5

(a) A malleolar screw is inserted perpendicular to the head of the ulna through the previously made drill hole. The screw should enter just anterior to the compartment of the ECU tendon, and be introduced until its tip protrudes ∼3 mm from the center of the denuded surface of the head of the ulna. (b) Schematic drawing of the previous intraoperative photograph.

Fig. 6

(a) The screw is advanced until the bone surfaces to be arthrodesed have been moderately compressed and the head of the screw is introduced slightly into the head of the ulna. (b) The bone gap of the osteotomized ulna should measure ∼5 mm, and the ECU tendon should be located at the dorsum.

Fig. 7

(a) Radiograph of the wrist showing the head of the ulna compressed against the radius with a malleolar screw, with a very small segment of ulna removed. (b) With the passing of time, the bone defect will get larger from resorbtion of the bone ends, mainly the proximal ulna stump.

Fig. 8

Schematic drawing of the structures providing stabilization of the proximal ulna. On the left, an anterior view showing the pronator quadratus. The FCU is not shown. On the right, a posterior view showing the interosseous membrane and the extensor carpi ulnaris tendon.

Fig. 9

With the forearm in pronation, the ECU tendon is located below the axis of rotation of the DRUJ. As the surgery is usually done with the forearm in this position, it is not uncommon to place the entrance of the screw dorsal to the ECU inadvertently, as shown in the top drawing. Using the technique here described, the surface of the ulna to be arthrodesed is the one facing the surgeon while the forearm is pronation, as seen in Figs. 2a,b. If the screw is introduced anterior to the ECU tendon, the latter will be displaced dorsally for added stability of the proximal ulna, as depicted at the bottom drawing.