A Radiographic Classification of Capitate Morphology and Its Association With Kienböck Disease

Area of Science:

• Orthopedic surgery
• Radiology
• Biomechanics

Background:

• Kienböck disease (KD) etiology is unclear, though negative ulnar variance (UV) is associated.
• The capitate bone's morphology may influence lunate loading and KD pathogenesis.

Purpose of the Study:

• To investigate the association between capitate morphology and Kienböck disease (KD).
• To classify capitate morphology based on radiographic joint line characteristics.

Main Methods:

• A case-control study involving 80 KD patients and 467 controls.
• Radiographic analysis of capitate morphology (Type I, II, intermediate) and ulnar variance (UV).

Main Results:

• Type II capitate was more prevalent in KD patients (30% vs 18% in controls).
• Negative UV (35% vs 7%) and Type II capitate (30% vs 18%) were significantly higher in KD patients.
• Multivariable analysis identified negative UV (OR=9.2) and Type II capitate (OR=2.7) as independent risk factors for KD.

Conclusions:

• A novel radiographic classification of capitate morphology is introduced.
• Type II capitate morphology is associated with Kienböck disease, independent of negative UV.
• Further research is needed on the mechanical and vascular roles of Type II capitate in KD.