Significance of Scapholunate Gap Width as Measured by Probe from Midcarpal

Background  Geissler's classification is widely accepted in arthroscopic diagnostics of scapholunate (SL) ligament injury. Thereby, probe insertion into the SL gap from the midcarpal would indicate treatment necessity in patients with SL tear as seen from radiocarpal view. Purpose  In this review, the SL gap width, examined by the probe from midcarpal, was arthroscopically assessed in patients with intact SL ligaments, who were treated for ulnar impaction syndrome. The review examined how often lax SL joints can be found in patients with no complaints with respect to the SL ligaments and in which the SL ligaments were proven to be intact from radiocarpal view. We suspected that probe insertion, as an indicator for a lax joint, does not affect the outcome in ulnar impaction treatment. Patients and Methods  A total of 32 patients with clinically diagnosed ulnar impaction syndrome were arthroscopically treated by central resection and debridement of the triangular fibrocartilage; 8 patients underwent concurrent ulnar shortening, and 4 of them finally hardware removal. All patients were examined preoperatively as well as after 3, 6, and 12 months following arthroscopy, respectively, after ulnar shortening or hardware removal. Results  In 14 patients, the probe could not, in 18 patients, the probe could be inserted into the SL gap. There was neither any significant difference in the improvement of pain, grip strength, Krimmer, or DASH score, nor for any of the radiographic angles between the two groups. Conclusion  Laxity of the SL ligament allows the probe to be inserted into the SL gap from midcarpal in some patients. This finding, therefore, does not necessarily imply the necessity of treatment when there is partial rupture seen from radiocarpal view. Level of Evidence  Level III, case-control study.