Facet Inclinations and Interfacet Angle of the Distal Radius on Posteroanterior Radiographs: Clinical Associations With 3 Carpal Pathologies.

Purpose: The radiographic interfacet angle (IFA), scaphoid facet inclination (SFI), and lunate facet inclination (LFI) of the distal radius were measured in patients with 3 distinct wrist pathologies to determine whether there is an association between these radiographic measurements and these conditions.

Methods: Posteroanterior wrist radiographs were compiled from patients with 3 types of common wrist pathologies (scaphoid waist fracture [n = 54], scapholunate [SL] dissociation [n = 23], and dorsal ganglion [n = 51]). The patients were all Caucasians aged 20 to 45 years who met strict radiographic criteria. The IFA, SFI, and LFI values of these patients were compared with those obtained from 400 normal wrist radiographs of subjects who met the same selection criteria.

Results: In men with a scaphoid waist fracture, the IFA and SFI were significantly greater than in normal men, whereas the LFI was significantly lower. In the SL dissociation group, for all patients and for subgroups stratified according to sex, the IFA and SFI were significantly lower than in the normal matched groups. In the dorsal ganglion group, differences were found in the IFA and SFI for women, but not for men.

Conclusions: The facet orientations of the distal radius in patients with scaphoid fracture, SL dissociation, and dorsal ganglion differed from those in the normal population. The IFA alone is most likely to be associated with all 3 pathologies. The SFI and LFI are less likely to be associated with patients with carpal pathologies.

Clinical Relevance: Patients with a greater IFA may be susceptible to scaphoid fractures when they fall on an overstretched hand. Patients with a smaller IFA may be susceptible to SL dissociation when they fall on an overstretched hand.