Background: Subchondral bone stiffness is thought to be involved in osteoarthritis pathogenesis. Our objective was to determine if a CT imaging technique, which measures density in relation to depth from the subchondral surface, could predict the stiffness of proximal tibial subchondral bone. A second objective was to determine whether cartilage degeneration (an indicator of osteoarthritis) affected predictions.
Methods: Thirteen proximal tibial compartments (4 medial, 9 lateral) from 10 male donors (age: mean 73.2, SD 10.6 years) were scanned using quantitative CT. We assessed average subchondral bone mineral density across different depths (0–2.5, 0–5, 0–10 mm) and layers (2.5–5, 5–10 mm) measured relative to the subchondral surface. We classified cartilage status as normal or degenerated using the International Cartilage Repair Society system. We performed macro indentation testing directly at the subchondral surface, and related stiffness to density measures using power-law regression models adjusted for side, age and cartilage status. We tested the coincidence of normal and degenerated regression models using F test statistics.
Findings: Density measures nearest the subchondral bone surface (0–2.5 mm) were most effective at predicting subchondral bone stiffness (r2 = 0.67, p < 0.001). The predictive ability of depth-specific density measures decreased when density was averaged across larger depths or layers deep to the subchondral surface. Cartilage status did not affect model predictions.
Interpretation: Depth-specific density measures have potential use as in vivo imaging tools for characterizing subchondral bone density and estimating stiffness. This information could help explain the role of subchondral bone in osteoarthritis pathogenesis.
|1990||Choi K, Kuhn JL, Ciarelli MJ, Goldstein SA. The elastic moduli of human subchondral, trabecular, and cortical bone tissue and the size-dependency of cortical bone modulus. J Biomech. 1990;23(11):1103-1113.|
|1972||Radin EL, Paul IL, Rose RM. Role of mechanical factors in pathogenesis of primary osteoarthritis. Lancet. March 4, 1972;299(7749):519-522.|
|1971||Mankin HJ, Dorfman H, Lippiello L, Zarins A. Biochemical and metabolic abnormalities in articular cartilage from osteo-arthritic human hips, II: correlation of morphology with biochemical and metabolic data. J Bone Joint Surg. April 1971;51A(3):523-537.|
|1970||Timoshenko SP, Goodier JN. Theory of Elasticity. 3rd ed. New York, NY: McGraw-Hill Book Co; 1970.|
|1977||Carter DR, Hayes WC. The compressive behavior of bone as a two-phase porous structure. J Bone Joint Surg. 1977;59A(7):954-962.|
|1997||Li B, Aspden RM. Composition and mechanical properties of cancellous bone from the femoral head of patients with osteoporosis or osteoarthritis. J Bone Miner Res. 1997;12(4):641-651.|
|1986||Little RB, Wevers HW, Siu D, Cooke TDV. A three-dimensional finite element analysis of the upper tibia. J Biomech Eng. May 1986;108(2):111-119.|
|1984||Brown TD, Radin EL, Martin RB, Burr DB. Finite element studies of some juxtarticular stress changes due to localized subchondral stiffening. J Biomech. 1984;17(1):11-24.|
|2001||Day JS, Ding M, van der Linden JC, Hvid I, Sumner DR, Weinans H. A decreased subchondral trabecular bone tissue elastic modulus is associated with pre‐arthritic cartilage damage. J Orthop Res. September 2001;19(5):914-918.|
|1991||Grynpas MD, Alpert B, Katz I, Lieberman I, Pritzker KPH. Subchondral bone in osteoarthritis. Calcif Tiss Int. January 1991;49(1):20-26.|
|1994||Keyak JH, Lee IY, Skinner HB. Correlations between orthogonal mechanical properties and density of trabecular bone: use of different densitometric measures. J Biomed Mater Res. November 1994;A28(11):1329-1336.|
|1994||Zysset PK, Sonny M, Hayes WC. Morphology-mechanical property relations in trabecular bone of the osteoarthritic proximal tibia. J Arthoplast. 1994;9(2):203-216.|
|1992||Linde F, Hvid I, Madsen F. The effect of specimen geometry on the mechanical behaviour of trabecular bone specimens. J Biomech. 1992;25(4):359-368.|
|2003||Morgan EF, Bayraktar HH, Keaveny TM. Trabecular bone modulus–density relationships depend on anatomic site. J Biomech. July 2003;36(7):897-904.|
|2019||Kalajahi SMH, Nazemi SM, Johnston JD. Separate modeling of cortical and trabecular bone offers little improvement in FE predictions of local structural stiffness at the proximal tibia. Comput Methods Biomech Biomed Eng. 2019;22(16):1258-1268.|
|2020||Kalajahi SMH, Nazemi SM, Johnston JD. An exclusion approach for addressing partial volume artifacts with quantititive computed tomography-based finite element modeling of the proximal tibia. Med Eng Phys. February 2020;75:95-100.|
|2018||Michalak GJ. Concurrent Assessment of Knee Cartilage Morphology and Bone Microarchitecture Using Contrast-Enhanced HR-PQCT Imaging [Master's thesis]. Calgary, AB: University of Calgary; May 2018.|
|2018||Hosseini Kalajahi SM. Addressing Partial Volume Artifacts With Quantitative Computed Tomography-Based Finite Element Modeling of the Human Proximal Tibia [Master's thesis]. Saskatoon, SK: University of Saskatchewan; April 2018.|