Intercarpal arthrodesis for static and dynamic volar intercalated segment instability.

Since 1982 seven patients with volar intercalary segment instability (VISI) have been operated on at the Massachusetts General Hospital. All had preoperative wrist pain and described a painful "clunk" with ulnar deviation. In each case there was palpable evidence of instability when the wrist was deviated ulnarly that produced a "buckling" sensation as the distal and proximal rows rotated with ulnar deviation. Arthrograms in six patients and a cineradiography in one patient confirmed that this buckling correlated with volar rotation of the lunate and triquetrum and dorsal rotation of the capitate and hamate. All the patients had some type of intercarpal arthrodesis including four capitate-lunate-triquetrum hamate (CLTH), one lunate-triquetrum (LT), one lunate-triquetrum-hamate (LTH), and one triquetrum-hamate (TH). Surgical findings included the position of the lunate that had rotated on the capitate so that it was tilting volarly and the major ligament instability was between the proximal and distal rows although ligament tears were also present between lunate and triquetrum. Arthrodesis of the proximal and distal rows provided relief of wrist pain in five of six patients. The one patient with the arthrodesis limited to the proximal row had a poor result. Of the five successful cases, the postoperative range of wrist motion was 81 degrees of extension/flexion arc (63% of the normal contralateral) and 35 degrees of radial and ulnar deviation arc (57% of the normal contralateral wrist). The grip strength postoperatively averaged 58 pounds (74% of the normal contralateral side).