A Novel Trigonometry Equation; Precisely Restoring Distal Radius Volar Tilt

Abstract

Introduction: Displaced distal radius fractures are often associated with loss of normal volar tilt. Restoration of volar tilt is critical for preservation of normal wrist biomechanics. There is no standardized way to reliably and predictably restore the volar tilt. We introduce a technique of using a locking screw in the most proximal hole of a locking plate to provide a predictable restoration of volar tilt in dorsally displaced distal radius fractures. The desired correction is dictated by the locking screw length to be used which can be calculated by the following equation: tan(θ) x d=b. In this equation, θ is the desired correction angle to restore the volar tilt, d is the distance from the locking screw to the volar bend of the plate, and b is the length of the locking screw. Methods: We performed a retrospective review of 20 patients who sustained distal radius fractures. The volar tilt status post closed reduction of the distal radius fracture was recorded for each patient. Additionally, the volar tilt status post open reduction internal fixation with our novel technique using a synthes 2.4mm volar plate was recorded for each patient. The length of the locking screw was documented and correction angle was calculated for each case. Results: The average volar tilt status post closed reduction of the distal radius fracture was -3.3 degrees. The average volar tilt status post open reduction internal fixation with our novel technique was 6.55 degrees. The resultant correction angle post-operatively was 10.75 degrees. The average length of the locking screw was 6.7 mm and the distance from the locking screw to the volar bend of the plate was 25 mm in all cases. Conclusion: Restoration of volar tilt is one of the most critical steps in the treatment of distal radius fractures. An accurate and highly reproducible technique is required to consistently achieve this goal. A simple technique using a locking screw in the most proximal hole of a locking plate can be utilized to restore the volar tilt accurately and reliably in dorsally displaced distal radius fractures.