Healio
Healio
September 10, 2009
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Scapholunate, lunotriquetral laxity may be greater than what is described in Geissler system

SAN FRANCISCO — The Geissler classification system cannot be used to determine the pathologic instability in atraumatic wrists due to a larger range of laxity within the scapholunate (SL) and lunotriquetral (LT) joints than has previously been reported, according to a cadaveric study presented here.

Todd R. Rimington, MD, pointed out that grade II and a percentage of grade III interosseous ligaments — previously described as pathologic — were found to be present in nearly half of all atraumatic wrists, suggesting physiologic laxity.

“The problem is that in our experience, SL and LT laxity has been greater than Geissler originally described,” Rimington said at the Combined Annual Meeting of the American Society for Surgery of the Hand and the American Society of Hand Therapies. “Before Geissler’s criteria are used to guide treatment, it’s important to define the normal range of physiologic laxity.”

Study procedures

Rimington’s team performed standard wrist arthroscopy on 83 atraumatic, cadaveric wrist specimens. They determined the scapholunate ligament (SLIL) and lunotriquetral ligament (LTIL) grades using the Geissler classification system during arthroscopy. They also documented lunate morphology.

Radiographs were used to determine the scapholunate angle and scapholunate gap measurements prior to the procedure itself. Statistical analyses included chi-square, various correlation coefficients and both bivariate and multivariate models.

According to the study, 5% (4) of the SLIL in all specimens were found to be grade I, 34% were grade II, 48% were grade III and 13% were grade IV. In the LTIL, 20% were grade I specimens, 48% were grade II, 30% were grade III and 1% were grade IV.

Furthermore, both LTIL and SLIL grades increased with age without any correlation to lunate morphology or radiographic measurements of SL gap or angle.

“We have concluded that the physiologic range of interosseous ligament laxity is greater than Geissler originally described,” Rimington said. “There is an age-related progression of interosseous ligament laxity. We agree with previous studies that have shown this, and we believe our statistics strengthen the literature on this topic.”

“An apparent paradox”

“Performing a study in 83 specimens is indeed monumental, no matter what you look at, so I congratulate you for that,” moderator William B. Geissler, MD, said. “I was wondering if you could elaborate on what is an apparent paradox with the lack of correlation between your radiographic SL widening and correlation with the grade.”

“That is an interesting thing,” Rimington said. “I think it’s showing … maybe at that point that we haven’t crossed into dynamic instability yet, and therefore we don't see it on the radiographs.”

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