Changes in bone density, microarchitecture, and biomechanical properties after plate removal in surgically treated distal radius fractures: a prospective study

Abstract

Purpose Removal of volar locking plates after healing of a distal radius fracture is becoming increasingly common. However, it is unclear how the fracture healing proceeds and which defects remain. The aim of this study was to assess changes in bone microarchitecture and biomechanical properties in surgically treated radius fracture after volar locking plate removal. Methods Twelve patients were recruited after undergoing plate removal. High Resolution Quantitative Computed Tomography (HR-pQCT) was used to perform scans of the fractured and contralateral distal radius on average one (M1) and 16 months (M2) after plate removal. Parameters measured were cortical- (Dcomp), trabecular- (Dtrab) and total bone density (D100), as well as cortical thickness (Ct.Th). Axial bone stiffness (FE.Kaxial) was determined through linear micro-finite element analysis (µFEA). Results At M1, no significant differences between fractured and contralateral side were detected except for Dcomp. At the fractured side, all parameters except for Dtrab increased significantly between M1 and M2. At M2, Ct.Th and FE.Kaxial were significantly higher at the fractured side compared to the contralateral side, but Dcomp remained significantly lower. Qualitatively, closure of the screw holes was observed between M1 and M2, while large trabecular defects remained. Conclusion Bone (re)modeling at the distal radius is an ongoing process even after plate removal and leads to a partial exaggeration of the bone properties relative to the intact contralateral side. It seems that the bone regains its biomechanical competence by closing screw holes and increasing cortical thickness, which compensates for trabecular defects that cannot be repaired. Level of evidence III.