Distal radius fracture is one of the most common fractures of the forearm and accounts for approximately 16% of all skeletal fractures. Distal radial fractures are associated with injuries to the TFCC and carpal ligaments that may lead to carpal malalignment later. The purpose of this study was to assess the frequency of carpal instability on radiological basis following conservative management of distal radius fractures. Other objective was to identify other factors including carpal malalignment in an attempt to predict the final functional outcome.

In a prospective study, 100 distal radial fractures treated with conservative method were followed–up with serial radiographs for assessment of various radiological parameters. The alignment of each wrist was checked radiographically in pre reduction, immediate post–reduction and subsequently at 6–week follow–up radiographs. Serial measurements of radial length, dorsal tilt, radial inclination, scapho–lunate, radio–lunate, radioscaphoid, scapho–capitate angles and effective radiolunate flexion (ERLF) angle were made. Regression analysis showed high correlation among the severity of axial shortening, prereduction dorsal angulation and radio–carpal malalignment pattern with loss of reduction at 6 week. Two patterns of carpal malalignment were identified depending upon the effective radiolunate flexion (ERLF) measured on pre–reduction radiographs. The midcarpal malalignment was seen in 82% radial fractures with the lunate following the dorsiflexed fracture fragment and a measured ERLF of less than 25⁰. The second pattern of radio–carpal malalignment showed the fracture fragment to dorsiflex without taking the lunate with a measured ERLF of more than 25⁰. The scaphoid did not follow the fracture fragment in both the patterns of malalignment.

Our study highlights the importance of various radiological parameters on post–reduction radiographs as a predictor of carpal instability.