Abstract
Question/Purpose Carpal kinematics may be influenced by the manipulation of carpal dimensions. This
may provide a surgical alternative to unpredictable soft tissue reconstruction for
scapholunate dissociation. The purpose of this study was to determine if altering
capitate height can correct dorsal intercalated segment instability (DISI).
Materials and Methods Five cadaveric wrists had baseline radiolunate (RL) angles and scapholunate (SL)
intervals measured fluoroscopically, confirming no baseline DISI. We simulated open-
and clenched-fist testing via a constant load of the wrist extensors and sequential
loading of the digital flexors. We confirmed no baseline static/dynamic DISI. The
SL ligament and secondary stabilizers (scapho-trapezio-trapezoid [STT] and dorsal
intercarpal ligaments) were transected. Repeat loading and fluoroscopic measurements
confirmed creation of static DISI. Capitate height was altered in three interventions:
2 mm shortening osteotomy of capitate waist, 7 mm shortening osteotomy of capitate
waist, and 2 mm lengthening of original capitate height by insertion of a spacer at
capitate waist. The osteotomized capitate was stabilized with a Kirschner wire; RL
angles and SL intervals were measured via fluoroscopy during open- and clenched-fist
testing. Primary and secondary outcomes were change in RL angle and SL interval, from
the DISI stage to each capitate shortening and lengthening stage.
Results SL ligament and secondary stabilizers sectioning created a DISI pattern, with abnormal
RL angles (>15°) and widened SL intervals. Neither capitate shortening nor overexpansion
corrected RL angles or SL intervals in any DISI-induced wrists.
Conclusions Under the conditions studied, isolated capitate shortening or lengthening did not
correct radiographic DISI posturing of the lunate following sectioning of the SL and
STT interosseous ligaments. Further study of carpal kinematics with more substantial
bone changes and loading of adjacent joints may be beneficial.
Clinical relevance Surgeons performing capitate shortening osteotomy in isolation should not expect
to improve DISI.
Keywords
capitate shortening osteotomy - dorsal intercalated segment instability - scapholunate
dissociation
