What is the Optimal Location for Bone Graft Harvest in the Distal Radius?
Andrew P Matson, MD1; Andrew E Federer, MD1; Erin M Meisel, MD1; Stephen R Barchick, BS2; David S Ruch, MD3; Marc J. Richard, MD4; (1)Duke University Health System, Durham, NC, (2)Duke University School of Medicine, Durham, NC, (3)Duke University, Durham, NC, (4)Department of Orthopedic Surgery, Duke University, Durham, NC
Autogenous bone grafting from the distal radius (DR) is commonly performed to provide cancellous bone that promotes osseous fusion or fracture healing, particularly in the case of scaphoid nonunion. Despite its widespread use, the optimal donor site within the DR has not been described. The purpose of this study was to identify regions within the distal radius containing the highest volume and density of cancellous bone, based on radiographic parameters.
Materials & Methods
Thirty-four consecutive wrist computed tomography (CT) scans in 33 patients without DR pathology at a single institution were retrospectively identified. Using three dimensional imaging reconstruction software, we systematically identified six spherical regions of interest (ROI) within the DR cancellous bone of each patient. These ROI were distinguished primarily as either distal (10 mm from articular surface) or proximal (20 mm from articular surface), and secondarily radial, central, or ulnar (Figure). In each spherical ROI, volumetric measurements were recorded and mean Hounsfield unit (HU) value was recorded as a proxy for bone density. Statistical analysis was performed using the Student's t-test for two-group comparisons, and least squares mean differences comparisons for multi-group comparisons with p-values adjusted for using Tukey's method.
Compared to proximal bone, distal bone had higher volume (0.82 vs 0.28 cm3, p<0.001) and higher density (175 vs. 153 HU, p<0.001) on average. Among the six spherical ROIs, the distal central region had the highest average volume (1.20 cm3) and was significantly higher than all other regions (all p<0.001). The distal ulnar region had the highest average density (193 HU), and was significantly higher than two of the three proximal regions (central and ulnar, both p<0.001) (Table).
Radiographically, cancellous bone is highest in volume and density at the more distal aspects of the bone. Based on these results, we recommend performing a corticotomy for distal radius cancellous bone graft at 10 mm proximal to the articular surface, with an ulnar bias relative to the coronal midline of the bone.
Using three dimensionally reconstructed images, volume and density measurements were performed in spherical regions by defining circular regions of interest within the borders or cortical bone on the axial cuts (top left) at 10 mm and 20 mm proximal to the radiocarpal articular surface. This translated to spherical regions that could be simultaneously viewed on customized coronal (bottom left) and sagittal (bottom right) series.
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