Can carpal malalignment predict early and late instability in nonoperatively managed distal radius fractures?

The purpose of this study was to assess the frequency of carpal instability as a concomitant lesion in distal radius fractures and identify other factors including carpal malalignment in an attempt to predict the final radiological outcome more accurately following conservative treatment of distal radius fractures. An observational study from patient records and standardised radiological follow-up examinations as data sources was used. The alignment of each wrist was checked radiographically immediately post-reduction and subsequently at 1- and 6-week follow-up assessments. Serial measurements of radial length, dorsal tilt, radial inclination, scapho-lunate, radio-lunate, radioscaphoid, scapho-capitate angles and effective radiolunate flexion angle were made. Regression analysis showed high correlation among the severity of axial shortening, pre-reduction dorsal angulation and radio-carpal malalignment pattern with early loss of reduction at 1 week. We found the age, severity of axial radial shortening, dorsal angulation, presence of dorsal comminution and radio-carpal malalignment pattern to be significant predictors of adverse radiological outcome at 6 weeks (late instability). Our study highlights the importance of radio-carpal instability pattern on post-reduction radiographs as a predictor of early and late instability.