Dynamic axial carpal instability

Abstract

I was intrigued by the recent article by Shin et al entitled “Dynamic Axial Carpal Instability: A Case Report” (J Hand Surg 1999;24A:781–785) and was surprised by statements the authors made that warrant clarification. Shin et al stated that the arthrogram done as part of the patient's evaluation showed “no abnormal dye passage between the scapholunate, lunotriquetral, or capitohamate joints.” How do they explain this finding in light of the fact that arthroscopy demonstrated “complete loss of integrity of the capitohamate interosseous ligaments”? Furthermore, the preoperative arthrogram showed a “slight leak” of dye through the triangular fibrocartilage complex (TFCC) and yet the authors reported that a tear of the TFCC was diagnosed arthroscopically that was large enough to mandate repair. These discrepancies raise 2 questions. First, how do the authors reconcile the differences between the negative arthrogram and the complete capitohamate ligament incompetence? The sensitivities and specificities of arthrograms for detecting intercarpal ligament tears range from 56% to 100% and 56% to 83%, respectively, in published reports. 1Chung KC Zimmerman NB Travis MT. Wrist arthrography versus arthroscopy: a comparative study of 150 cases.J Hand Surg. 1996; 21A: 591-594Abstract Full Text PDF Scopus (72) Google Scholar, 2Cooney WP. Evaluation of chronic wrist pain by arthrography, arthroscopy and arthrotomy.J Hand Surg. 1993; 18A: 815-822Abstract Full Text PDF Scopus (113) Google Scholar, 3Weiss A-PC Akelman E Lambiase R. Comparison of the findings of triple-injection cinearthrography of the wrist with those of arthroscopy.J Bone Joint Surg. 1996; 78A: 348-356Crossref Scopus (114) Google Scholar It surprised me that Shin et al did not comment on the importance of the negative arthrogram in evaluating their patient for this proposed new disorder of dynamic axial carpal instability. Is the arthrogram superfluous in the workup of patients with similar presentations? Second, why do the authors attribute the patient's symptoms to dynamic capitohamate instability rather than the TFCC tear? The case history and physical examination, which included ulnar-sided wrist tenderness and pain with ulnar deviation following a fall on the outstretched hand, are consistent with a TFCC tear, which is a common disorder that responds well to arthroscopic management.4Trumble TE Gilbert M Vedder N. Isolated tears of the triangular fibrocartilage: management by early arthroscopic repair.J Hand Surg. 1997; 22A: 57-65Abstract Full Text PDF Scopus (133) Google Scholar Why did the authors discount the TFCC tear and its subsequent repair as the source of the patient's symptoms and recovery, respectively? Shin et al present their case as an example of dynamic carpal instability in which the energy of trauma disrupted the capitohamate and scapholunate joints. It is unclear why they conclude this if the scapholunate interosseous ligament was interpreted as being intact on arthrogram and magnetic resonance imaging and showed no tears arthroscopically (just a suggestion of slight stretching). Geissler grade 2 ligament changes do not equal joint disruption. An extensive battery of diagnostic tests was completed in the workup of the patient presented, including special view radiographs, an arthrogram, trispiral tomograms, a bone scan, a magnetic resonance imaging scan, diagnostic lidocaine injections, and arthroscopy. Are all these tests required to make the proposed diagnosis? In this time of increased cost consciousness among physicians and third-party payers alike, we should always strive to establish diagnoses as expeditiously and cost effectively as possible. The authors missed a chance to comment on their recommendations for evaluating similar patients in the future without ordering such an exhaustive and expensive array of diagnostic modalities. Finally, did the patient described in the report receive workers' compensation for his injury and treatment? Secondary gain or its absence may have affected the outcome one way or the other and it would be useful to know this when examining and counseling other patients suspected of having similar pathology in the future.