Wrist Instability After Sectioning the Different Components of the Scapholunate Ligament and Dorsal Scapholunate Septum Using a Cadaveric Model

Purpose or Learning Objective: To study the effect of sectioning the different components of the scapholunate ligament-dorsal scapholunate septum (SL-DCSS) in a cadaveric model and assess the dynamic effects with four-dimensional computed tomography (4D-CT).

Methods or Background: Five fresh-frozen cadaveric specimens were imaged with 4D-CT while placed in a custom-made wooden frame before and after introduction of different SL-DCSS lesions. The lesions were created arthroscopically and consisted of ventral (VSL), dorsal (DSL), VSL + DSL, VSL + DSL + partial DCSS, and VSL + DSL + complete DCSS. With CT, dynamic acquisitions were obtained in flexion and extension (F-E) and in radial and ulnar (R-U) deviation. Relevant bony structures were segmented semiautomatically. Based on this, X, Y, and Z graphs were created to analyze the movement of the bones.

Results or Findings: With VSL sectioning, no SL diastasis occurred. Dorsal tilt increased with VSL sectioning. With DSL sectioning, SL diastasis was seen but only in F-E and not in R-U. With sectioning of multiple components, SL diastasis was observed in all movements. With VSL, DSL and VSL + DSL tilting in F-E was not concordant with tilting in R-U deviation. When the DCSS was completely sectioned, tilting increased significantly in all movements; SL diastasis was the most pronounced.

Conclusion: (1) SL diastasis does not occur with VSL lesions; however, with DSL lesions, it can also not be shown on R-U deviation. (2) The palmar attachment of the VSL, termed the extrinsic radioscapholunate ligament (RSL), may explain why dorsal tilt occurs with a VSL (and RSL) lesion. (3) Except for the most severe injury of all structures (SL + DCSS), the motion in R-U deviation is not concordant with F-E as classically thought. We believe the extrinsic ligaments restrain the expected motion. (4) The more components are injured, the more SL diastasis and tilting increases. (5) The DCSS plays an important role because SL instability is most pronounced when it is injured.

Publication History

Article published online:
26 May 2023