Effect of Gap Size on Ulnar Variance Changes in Malunited Distal Radius after Open Wedge Osteotomy with Volar Locking Plate without Bone Graft in Malunited Distal Radius

Abstract

Background: Distal radius malunion may result in wrist pain, decreased range of motion, midcarpal instability, and affect the quality of life of the patients. There are many osteotomy techniques to correct malunion of the distal radius. The usage of a volar locking plate can also avoid extensor tendon irritation problems. To date, no previous study has mentioned about relation of gap size and radiographic parameter after corrective osteotomy, leading to the question of this study. Objective: to determine whether the time to union and the post-operative radiographic parameter changes were affected by gap size in malunited distal radius patients who underwent opening wedge osteotomy with volar locking plate without bone graft. Method: Retrospectively and prospectively analyzed data from 24 patients, including gap size, union time, and three radiographic parameters (ulnar variance, radial inclination, and volar tilt). The three radiographic parameters were collected at preoperative, immediate postoperative, and at the union time. The average follow-up time was 6 months. Result: The average gap size was 4.7 mm. The average union time was 11.2 weeks. No significant loss of reduction was found regarding the three radiographic parameters. All radiographic parameters were improved. No correlations between gap size and union time, as well as the three radiographic parameters, were found. Preoperative volar tilt had a moderate negative correlation and time from injury had a positive moderate correlation with the union time. Conclusion: When performing corrective osteotomies of malunited distal end radius without bone graft, increasing gap size was not correlated with delay union time nor radiographic reduction loss. Decreasing preoperative volar tilt and delayed operation may negatively affect union time.