Articular cartilage is fluid-swollen tissue at the ends of synovial joints, which functions by providing a lubricated surface for articulation and facilitates efficient transmission of loads. Cartilage biomechanical function is highly dependent on the integrity of its matrix, consisting of water, collagen and proteoglycans (PG), and the interaction between these components. Consequently, alteration of articular cartilage matrix components, either by injury or degenerative conditions such as osteoarthritis (OA), results in compromised functional behaviour. This makes the assessment of this tissue essential early in the degenerative process to prevent or reduce further joint damage, often characterised by pain and immobility, with associated socio-economic impact.
Mechanical compression and indentation techniques have long been used to assess the biomechanical and functional integrity of articular cartilage in vitro. Although they have led to a general understanding of the bulk properties of the tissue and its subsequent changes due to osteoarthritis, there are limitations to these studies. This thesis aims to develop a new mechanical indentation framework to address the limitations of the conventional indentation techniques.
In this research, two new mechanical indentation frameworks were established where the two different indenters (cylindrical and ring-shaped flat-ended indenters) were integrated with ultrasound for assessing functional properties of articular cartilage during loading/unloading, i.e. deformation and recovery.
In these frameworks, articular cartilage osteochondral samples were subjected to loading/unloading while the response of the tissue at the middle was captured by ultrasound at the same time. The mechanical response of a wider continuum of articular cartilage in the loaded area and its surrounding region was captured in these frameworks, leading to the investigation of two parameters, L and TS, related to the surrounding tissue of the loaded area for functional assessment of cartilage. L is the distance between the ultrasound transducer and articular cartilage surface and TS is the transient thickness of articular cartilage during loading and unloading.
The capacity of the two mechanical indentation frameworks and new parameters (L and TS) to distinguish mechanically intact from proteoglycan-depleted tissue during loading/unloading was investigated. The ring-shaped flat-ended indenter, integrated with an ultrasound transducer, was shown to be capable of distinguishing normal from enzymatically degraded bovine osteochondral samples.
Then, the potential of the ring-shaped flat-ended indenter integrated with an ultrasound transducer for functional assessment of normal and different types of cartilage degeneration models (proteoglycan loss and collagen disruption) during deformation/recovery, was investigated. This was also used to investigate the interrelationship between cartilage matrix components with deformation and recovery. Classification Analysis based on Principal Component Analysis was used to investigate the capacity of the new parameters (L and TS) to assess the functionality of the tissue. Multivariate statistics based on Partial Least Squares regression was employed to identify the correlation between the response of the tissue in the indented area and its surrounding cartilage.
The results of this research indicate that there is a significant correlation between the responses of cartilage in the directly-loaded area with its surrounding region. While the deformation data was ineffective in distinguishing between normal and proteoglycan-depleted samples, the recovery data was more reliable for this degeneration model. For cartilage degenerated samples where the tangentially aligned collagen fibres at the cartilage surface were disrupted, deformation data was more efficient than recovery data for tissue integrity assessment. Therefore, it is concluded that both aspects of the cartilage biomechanical response, deformation and recovery, should be considered for a more reliable and efficient characterisation of the tissue’s integrity.
|1991||Ateshian G, Soslowsky L, Mow V. Quantitation of articular surface topography and cartilage thickness in knee joints using stereophotogrammetry. J Biomech. January 1991;24(8):761-776.|
|1982||Armstrong CG, Mow VC. Variations in the intrinsic mechanical properties of human articular cartilage with age, degeneration, and water content. J Bone Joint Surg. 1982;64A(1):88-94.|
|1976||Maroudas A. Balance between swelling pressure and collagen tension in normal and degenerate cartilage. Nature. April 29, 1976;260(5554):808-809.|
|1983||Muir H. Proteoglycans as organizers of the intercellular matrix. Biochem Soc Trans. December 1983;11(6):613-622.|
|2002||Wang CC-B, Deng J-M, Ateshian GA, Hung CT. An automated approach for direct measurement of two-dimensional strain distributions within articular cartilage under unconfined compression. J Biomech Eng. October 2002;124(6):557-567.|
|2004||Chahine NO, Wang CC-B, Hung CT, Ateshian GA. Anisotropic strain-dependent material properties of bovine articular cartilage in the transitional range from tension to compression. J Biomech. August 2004;37(8):1251-1261.|
|1993||Mow VC, Ateshian GA, Spilker RL. Biomechanics of diarthrodial joints: a review of twenty years of progress. J Biomech Eng. November 1993;115(4B):460-467.|
|1971||Clarke IC. Articular cartilage: a review and scanning electron microscope study, I: the interterritorial fibrillar architecture. J Bone Joint Surg. November 1971;53B(4):732-750.|
|2001||Chen AC, Bae WC, Schinagl RM, Sah RL. Depth- and strain-dependent mechanical and electromechanical properties of full-thickness bovine articular cartilage in confined compression. J Biomech. January 2001;34(1):1-12.|
|2001||Quinn TM, Allen RG, Schalet BJ, Perumbuli P, Hunziker EB. Matrix and cell injury due to sub-impact loading of adult bovine articular cartilage explants: effects of strain rate and peak stress. J Orthop Res. March 2001;19(2):242-249.|
|2002||Thibault M, Poole AR, Buschmann MD. Cyclic compression of cartilage/bone explants in vitro leads to physical weakening, mechanical breakdown of collagen and release of matrix fragments. J Orthop Res. November 2002;20(6):1265-1273.|
|1992||Spilker RL, Suh J-K, Mow VC. A finite element analysis of the indentation stress-relaxation response of linear biphasic articular cartilage. J Biomech Eng. May 1992;114(2):191-201.|
|1972||Hayes WC, Keer LM, Herrmann G, Mockros LF. A mathematical analysis for indentation tests of articular cartilage. J Biomech. September 1972;5(5):541-551.|
|2001||Kurz B, Jin M, Patwari P, Cheng DM, Lark MW, Grodzinsky AJ. Biosynthetic response and mechanical properties of articular cartilage after injurious compression. J Orthop Res. 2001;19(6):1140-1146.|
|2002||Hunziker EB. Articular cartilage repair: basic science and clinical progress. a review of the current status and prospects. Osteoarthritis Cartilage. June 2002;10(6):432-463.|
|1968||Maroudas A. Physicochemical properties of cartilage in the light of ion exchange theory. Biophys J. May 1968;8(5):575-595.|
|1992||Hardingham TE, Fosang AJ. Proteoglycans: many forms and many functions. FASEB J. February 1992;6(3):861-870.|
|1983||Hoch DH, Grodzinsky AJ, Koob TJ, Albert ML, Eyre DR. Early changes in material properties of rabbit articular cartilage after meniscectomy. J Orthop Res. 1983;1(1):4-12.|
|1991||Lai WM, Hou JS, Mow VC. A triphasic theory for the swelling and deformation behaviors of articular cartilage. J Biomech Eng. August 1991;113(3):245-258.|
|1981||Maroudas A, Bannon C. Measurement of swelling pressure in cartilage and comparison with the osmotic pressure of constituent proteoglycans. Biorheology. 1981;18:619-632.|
|1971||Kempson GE, Spivey CJ, Swanson SAV, Freeman MAR. Patterns of cartilage stiffness on normal and degenerate human femoral heads. J Biomech. December 1971;4(6):597-609.|
|1997||Poole CA. Articular cartilage chondrons: form, function and failure. J Anat. 1997;191(1):1-13.|
|2003||Korhonen RK, Laasanen MS, Töyräs J, Lappalainen R, Helminen HJ, Jurvelin JS. Fibril reinforced poroelastic model predicts specifically mechanical behavior of normal, proteoglycan depleted and collagen degraded articular cartilage. J Biomech. September 2003;36(9):1373-1379.|
|1986||Radin EL, Rose RM. Role of subchondral bone in the initiation and progression of cartilage damage. Clin Orthop Relat Res. December 1986;213:34-40.|
|1976||Kempson GE, Tuke MA, Dingle JT, Barrett AJ, Horsefield PH. The effects of proteolytic enzymes on the mechanical properties of adult human articular cartilage. Biochim Biophys Acta. May 28, 1976;428(3):741-760.|
|1989||Mow VC, Gibbs MC, Lai WM, Zhu WB, Athanasiou KA. Biphasic indentation of articular cartilage, II: a numerical algorithm and an experimental study. J Biomech. 1989;22:853-861.|
|1997||Khalsa PS, Eisenberg SR. Compressive behavior of articular cartilage is not completely explained by proteoglycan osmotic pressure. J Biomech. June 1997;30(6):589-594.|
|1976||Woo SL-Y, Akeson WH, Jemmott GF. Measurements of nonhomogeneous, directional mechanical properties of articular cartilage in tension. J Biomech. 1976;9(12):785-791.|
|1971||Kempson GE, Freeman MAR, Swanson SAV. The determination of a creep modulus for articular cartilage from indentation tests on the human femoral head. J Biomech. July 1971;4(4):239-250.|
|1987||Jurvelin J, Kiviranta I, Arokoski J, Tammi M, Helminen HJ. Indentation study of the biomechanical properties of articular cartilage in the canine knee. Eng Med. January 1987;16(1):15-22.|
|1984||Mow VC, Holmes MH, Lai WM. Fluid transport and mechanical properties of articular cartilage: a review. J Biomech. 1984;17(5):377-394.|
|1975||Maroudas A. Biophysical chemistry of cartilaginous tissues with special reference to solute and fluid transport. Biorheology. 1975;12(3-4):233-248.|
|2009||Fox AJS, Bedi A, Rodeo SA. The basic science of articular cartilage: structure, composition, and function. Sports Health. November–December 2009;1(6):461-468.|
|1991||Athanasiou KA, Rosenwasser MP, Buckwalter JA, Malinin TI, Mow VC. Interspecies comparisons of in situ intrinsic mechanical properties of distal femoral cartilage. J Orthop Res. May 1991;9(3):330-340.|
|1970||Muir H, Bullough P, Maroudas A. The distribution of collagen in human articular cartilage with some of its physiological implications. J Bone Joint Surg. August 1970;52B(3):554-563.|
|1990||Schmidt MB, Mow VC, Chun LE, Eyre DR. Effects of proteoglycan extraction on the tensile behavior of articular cartilage. J Orthop Res. May 1990;8(3):353-363.|
|1998||Basser PJ, Schneiderman R, Bank RA, Wachtel E, Maroudas A. Mechanical properties of the collagen network in human articular cartilage as measured by osmotic stress technique. Arch Biochem Biophys. March 15, 1998;351(2):207-219.|
|1963||Elmore SM, Sokoloff L, Norris G, Carmeci P. Nature of "imperfect" elasticity of articular cartilage. J Appl Physiol. 1963;18(2):393-396.|
|1986||Akizuki S, Mow VC, Müller F, Pita JC, Howell DS, Manicourt DH. Tensile properties of human knee joint cartilage, I: influence of ionic conditions, weight bearing, and fibrillation on the tensile modulus. J Orthop Res. 1986;4(4):379-392.|
|1982||Kempson GE. Relationship between the tensile properties of articular cartilage from the human knee and age. Ann Rheum Dis. October 1982;41(5):508-511.|
|2001||Chen SS, Falcovitz YH, Schneiderman R, Maroudas A, Sah RL. Depth-dependent compressive properties of normal aged human femoral head articular cartilage: relationship to fixed charge density. Osteoarthritis Cartilage. August 2001;9(6):561-569.|
|1995||Bay BK. Texture correlation: a method for the measurement of detailed strain distributions within trabecular bone. J Orthop Res. March 1995;13(2):258-267.|
|1998||Setton LA, Tohyama H, Mow VC. Swelling and curling behaviors of articular cartilage. J Biomech Eng. June 1998;120(3):355-361.|
|1996||Schinagl RM, Ting MK, Price JH, Sah RL. Video microscopy to quantitate the inhomogeneous equilibrium strain within articular cartilage during confined compression. Ann Biomed Eng. July–August 1996;24(4):500-512.|
|1970||Kempson GE, Muir H, Swanson SAV, Freeman MAR. Correlations between stiffness and the chemical constituents of cartilage on the human femoral head. Biochim Biophys Acta. July 21, 1970;215(1):70-77.|