Carpal alignment in distal radial fractures

BACKGROUND Carpal malalignment following the malunited distal radial fracture is described to develop as an adaptation to realign the hand to the malunion. It worsens gradually after healing of the fracture due to continued loading of the wrist. It is also reported to develop during the immobilization itself rather than after fracture healing. The present work was aimed to study the natural course and the quantitative assessment of such adaptive carpal realignment following distal radial fracture. METHODS In a prospective study, 118 distal radial fractures treated with different modalities were followed-up with serial radiographs for a year for assessment of various radiological parameters. RESULTS Two patterns of carpal malalignment were identified depending upon the effective radio-lunate flexion (ERLF) measured on pre-reduction radiographs. The midcarpal malalignment was seen in 98 radial fractures (83%) with the lunate following the dorsiflexed fracture fragment and a measured ERLF of less than 25 degrees. The second pattern of radio-carpal malalignment showed the fracture fragment to dorsiflex without taking the lunate with a measured ERLF of more than 25 degrees. The scaphoid did not follow the fracture fragment in both the patterns of malalignment. CONCLUSION It is better to assess distal radial fractures for any wrist ligamentous injury on the post-reduction film with the restored radial anatomy than on the pre-reduction film since most carpal malalignments get corrected with the reduction of the fracture. Similar carpal malalignment reappear with the redisplacement of the fracture as seen in pre-reduction radiographs and develops during the immobilization rather than as a later compensatory mechanism for the malunion.