Article Text

  1. E. C. Shin1,
  2. B. S. Edward1,
  3. R. Szabo1,
  4. R. Sohn1
  1. 1Orthopedic Department, University of California, Davis, Davis, CA.


Introduction Scapholunate dissociation is the most common carpal instability. The abnormal kinematics that subsequently develop leads to scapholunate instability and early osteoarthritis without treatment. Currently, acute and chronic scapholunate injuries are operated on when surgeons are confronted with scapholunate instability, defined as injuries to two of the three ligaments connecting the scaphoid and lunate. However, there is currently no universal procedure used to repair scapholunate dissociation injuries due to the lack of understanding of the kinematics in scapholunate injuries. Our goal is to use three-dimensional computed tomography technology to better undertand the biomechanics of the wrist and improve on current intraoperative care.

Methods Patients 18 to 80 years of age are enrolled if they have unilateral scapholunate dissociation injury. CT scans were obtained of both the injured and noninjured hand of each subject in eight different positions, including extreme flexion/extension, radial/ulnar deviation, neutral, grip, and dart throwing positions (2). Three-dimensional images were subsequently derived using advanced radiologic software. With these data, the wrist kinematics were analyzed to compare the wrist kinematics between the injured versus The noninjured hand.

Results Thus far, two patients have been enrolled in this study. With the data and analysis obtained to date, the scaphoid and lunate have been shown to display differing kinematics in the injured versus the noninjured hand.

Conclusion Preliminary results show a difference in the wrist kinematics in hands with scapholunate dissociation injury versus noninjured hands in each subject. Although this is expected, complete scientific analysis of these data will allow us to delineate whether an ideal axis exists between the scaphoid and the lunate to allow for improved intraoperative care.

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