Volar Locking Plate Fixation for Distal Radius Fractures Distal to the Watershed Line with an Intact Lunate Volar Rim

Background: We treated distal radius fractures (DRFs) beyond the watershed line without fracture of the lunate volar rim using a volar locking plate (VLP) and report the radiological and clinical outcomes at least 3 years after surgery. Methods: In 41 consecutive patients between January 2012 and August 2017, the fragment was composed of the radial styloid process (distal to the watershed line) and the lunate volar rim was intact. We evaluated demographic factors, radiological features and radiological/clinical outcomes at the final follow-up. Results: Twenty-nine patients were followed and evaluated. The mean follow-up period was 5.7 years. The mean patient age was 52.7 years and 24 patients had intracapsular intra-articular fractures. The fracture line was present in the lunate fossa in all patients. Twenty patients were classified as Soong grade 2, and five and four patients were grades 1 and 0, respectively. No radiological parameter (volar tilt, radial inclination, step-off and ulnar variance) was significantly different between the affected and contralateral normal sides. The mean visual analogue scale pain score and Disabilities of the Arm, Shoulder and Hand score, as well as the range of movement of the wrist, were not different between the affected and contralateral normal wrists. Finally, the grip strength on the affected side was 92% of the contralateral value. Major complications, such as nonunion, malunion and tendon rupture, were absent. Conclusions: DRFs distal to the watershed line with an intact lunate volar rim are rare and easy to miss. Careful inspection of 3D-CT images is necessary to determine these injuries, and the optimal choice for proper fixation of the fragment amongst the commercial VLPs would result in satisfactory radiological and clinical outcomes. Level of Evidence: Level IV (Therapeutic).