Abstract
Letters of comment about recently published papers should be sent by email to:
Letters are sent to the authors of the original papers for their comments but will be published without a reply if the authors do not wish to make a comment. The Editor reserves the right to make editorial and literary changes to letters and to reject those deemed to be of insufficient interest to readers.
Dear Sir,
The authors of this letter are absolutely right. Excising the distal portion of the scaphoid in isolated STT osteoarthritis often induces abnormal DISI carpal malalignment and occasionally a symptomatic dorsal midcarpal instability. Certainly, this is the most feared complication of the procedure, as already emphasized in our initial publication (Garcia-Elias et al., 1999). The biomechanical consequences of excising a portion of the scaphoid were further discussed (Garcia-Elias and Lluch, 2001) and we warned against excision when there is substantial DISI malalignment before surgery. The case reported here, however, did not have substantial malalignment and yet the wrist was destabilized with the procedure. This is not the first case reported and the reasons remain obscure. It is probable that there are two types of STT osteoarthritis: the isolated degeneration of the STT joint and the STT involvement secondary to a chronic asymptomatic dorsal midcarpal instability, the so-called CLIP wrist. In the latter, the wrist may show perfect alignment preoperatively, and yet a hyperlax or insufficient dorsal midcarpal capsule often associated with absence of the dorsal scaphotriquetral ligament may allow passive dorsal subluxation of the capitate during ulnar deviation-flexion (Garcia-Elias, 2008). Should a case like this be treated by distal scaphoid resection, the dorsal translation vector of the capitate would provoke further dorsal capitolunate subluxation, as seen in Figure 2 of this case report. By contrast, if the midcarpal socket is constrained by a reinforced dorsal capsule, the tendency for dorsal subluxation of the capitate is neutralized. We now add to our previous warning the recommendation of ruling out a dorsal midcarpal instability (positive posterior drawer’s test under fluoroscopic control) before deciding on surgery. If the capitate cannot be subluxed dorsally, the chances for a resection arthroplasty to succeed are higher than if there is already a dorsal midcarpal instability, in which case an STT arthrodesis would probably be a better treatment option. Indeed, this pathology is not as simple as it appeared two decades ago when it first attracted our attention.