Osseous microarchitecture of the scaphoid: Cadaveric study of regional variations and clinical implications

Abstract

Bone strength and structure are closely associated with fracture and screw fixation, however osseous micro architecture on scaphoid has not been clearly addressed. We conducted histomorphometric study of the scaphoid using micro CT to find regional variations and differences in the scaphoid to provide better understanding of fracture mechanism and suggest optimal screw position. We divided scaphoid into eight regions and collected regional data from eleven different cadaveric scaphoids. A computer program was used to measure parameters, which includes mean subchondral bone thickness, bone mineral density for bone density parameters, and tissue mineral density, trabecular thickness, trabecular spacing, trabecular number and bone volume fraction for bone quality parameters. All bone strength parameters were measured the maximum value in the regions where scaphoid articulates with radius. Articular regions presented higher bone strength parameters and thicker subchondral bone. The minimum value of trabecular number was in midcarpal side of waist portion. There was trend of higher subchondral bone thickness in the scaphoid which articulates with capitate and radius. This histomorphometric study showed regional variation of the scaphoid in terms of bone density and quality parameters. Waist portion presented thick subchondral and trabecular bone for high cross section moment of inertia against bending. Three point bending for scaphoid fracture and vertical screw placement are suggested based on these variations.

3D computational anatomy of the scaphoid and its waist for use in fracture treatment

“…Interestingly, this zone corresponded to the mid-portion of the scaphoid where the centre of the waist is located. Su-Bum et al [37] found in CT scans of 20 male scaphoids the highest bone density parameters at regions that articulate with the radius and the capitate. The low bone density at the centre combined with the narrow anatomical shape of the waist explains the frequency of fractures at this site which is approximately 75% of all scaphoid fractures [3].…”

Application of high-resolution peripheral quantitative computed tomography in a clinical setting

“…However, extremity length was not taken into account in the previous HR-pQCT studies in adults with OI, and the effects of bone deformities on scan region were not discussed. Also, trabecular void spaces have been noted on HR-pQCT in OI [62], but their influence on HR-pQCT parameters has not been described. Evaluation of the feasibility of using HR-pQCT in OI is limited to a small study in nine children with OI [64].…”

“…Additionally, it may, as a single parameter, not fully describe the complexity and heterogeneity of OI. HR-pQCT has recently been used to investigate bone microarchitecture in adults with OI as compared to non-OI populations [61][62][63], but the small sample sizes in these studies may not have fully captured the heterogeneity in OI. Furthermore, difficulties may potentially be faced when using HR-pQCT in OI, which were not addressed in these studies.…”

“…Several aspects should be considered when using HR-pQCT to evaluate scaphoid fracture healing. For example, we adjusted standard evaluation protocols to only compute trabecular parameters and include the cortex in this computation as the outer bone layer (being subchondral rather than cortical bone) had previously been found to approximate 1-1.5 times the trabecular thickness of scaphoid bones [62]. Furthermore, standard compression tests could not be directly applied to µFE-models of the scaphoid bone due to the complex three-dimensional shape of the bone.…”