Scaphoidectomy and Capsulodesis for SNAC or SLAC Stage II

Abstract

Although the initial pathology differs between the scapholu-nate advanced collapse (SLAC) and scaphoid nonunion advanced collapse (SNAC) patterns of arthritis, they both end up causing abnormal load transmission between the scaphoid and the radius, which leads to a fairly predictable pattern of wrist arthritis. 1,2 In SLAC arthritis, the chronic disruption of the scapholunate interosseous ligament allows the capitate to migrate proximally. In SNAC arthritis, the chronic scaphoid nonunion disrupts the normal chain of connection between the scaphoid and the lunate. 3,4 These conditions result in a progressive pattern of degenerative arthritis that first involves the radioscaphoid articulation with osteophytes forming near the radial styloid (Stage I), followed by arthritis throughout the radioscaphoid articulation (Stage II). As de-generation progresses, the midcarpal joint becomes involved at the capitolunate joint. End stage SLAC or SNAC (Stage IV) results in arthrosis of the radiolunate articulation (►Fig. 1). Patients with SLAC or SNAC wrist arthritis present with pain and suffer from decreased range of motion (ROM) in the wrist. In about 50% of cases there is a remote history of trauma, often without any acute treatment. Upon clinical examination, dorsoradial swelling of the wrist with decreased wrist motion is common. Radiographs are useful to determine the stage of arthritis as just described (►Fig. 2). Sometimes patients present with a ganglion but without significant pain. Efforts to excise the ganglion in these arthritic wrists will result in rapid recurrences of the cyst. The scaphoid shift test may produce pain or crepitus, which helps to differentiate an idiopathic ganglion cyst from one due to arthritis. 5-8 Computed tomography (CT) scans can be useful, especially in the evaluation of the capitate-lunate joint (►Fig. 3). Sagit-tal-plane CT scans with reconstructions in the plane of the scaphoid are very useful in determining the degree of involvement of the radioscaphoid and radiolunate articulation (►Fig. 4). When there is no significant involvement of the capitolunate joint, the scaphoidectomy procedure can take advantage of the functioning articulation between both the capitolunate and the radiolunate joints. When there is involvement of the radial styloid without degeneration of the Keywords ► scapholunate advanced collapse (SLAC) arthritis ► scaphoid nonunion advanced collapse (SNAC) arthritis ► wrist arthritis ► scaphoid nonunion ► capsulorrhaphy Abstract Two common types of wrist arthritis are scapholunate advanced collapse (SLAC) and scaphoid nonunion advanced collapse (SNAC). In stage II SLAC or SNAC, there is arthritis between the scaphoid and the radius, sparing the cartilage between the capitate and the lunate and between the lunate and the radius. When nonsurgical treatment failed, scaphoidectomy plus capsulorrhaphy was used in 8 patients to provide pain relief without requiring an arthrodesis or compromising the radiolunate articulation. After surgery the pain scores improved from 8.5 preoperatively to 2.4 postoperatively. The Disabilities of the Arm, Shoulder, and Hand (DASH) score averaged 21, and the grip strength improved from 18 to 28 kg (81% of the contralateral side).