Abstract
Background Wrist anatomy variability is associated with differing susceptibility to pathology.
For example, a flat radial inclination is associated with Kienbock's disease. Lunate
facet inclination (LFI) also exhibits variability. Its relationship with other wrist
features is poorly documented.
Purposes We tested the hypothesis that high LFI is associated with increased uncovering of
the lunate, negative ulnar variance (UV), and type 2 lunates to balance forces across
wrists.
Methods In total, 50 bilateral and 100 unilateral wrist posteroanterior radiographs were
reviewed. Lunate type, lunate uncovering index (LUI), lunate tilting angle (LTA),
UV, and sigmoid notch angle (SNA) were measured, and correlation with LFI was assessed
on 150 right wrist radiographs followed by an assessment of differences based on lunate
morphology. Symmetry of 50 bilateral wrists was assessed.
Results There was no correlation of LFI with lunate morphology, LUI, and LTA. There was a
low correlation of LFI with SNA and UV. There was an inverse relationship between
UV and SNA. Wrists with type 2 lunates had more oblique sigmoid notches and higher
LTA in comparison to wrists with type 1 lunates. Side-to-side comparison revealed
strong correlation except for LUI, which exhibited moderate correlation.
Conclusions There is no correlation between LFI, LUI, and lunate morphology. Type 2 lunates are
associated with higher LTA and more oblique SNA. Wrists were symmetrical.
Clinical Relevance Factors other than lunate morphology are essential in balancing forces across wrists.
A better understanding of soft tissue and other factors will improve the understanding
of wrist biomechanics and pathology. Contralateral wrist radiographs can guide reconstructive
surgery.
Keywords
radius - ulna - lunate - morphology - radiograph
