Characterization of OA Severity in Knee Articular Cartilage in-Vivo Using MR Imaging and Loading Techniques

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Abstract and keywords

Early osteoarthritis (OA) is primarily associated with proteoglycan (PG) loss and changes in collagen structure. MR T2 imaging of knee under in-vivo loading may help to further reveal the differences between healthy and OA cartilage.

This study investigated the in-vivo loading effect on MR T2 values of human knee patellar cartilage. The results demonstrated T2 value distributions in patellar cartilage were inhomogeneous. In-vivo loading had a site-specific influence on participants’ T2 values. The in-vivo loading produced a significant difference on T2 values in the middle region of interest (ROI) of patellar cartilage (p=0.004<0.025), but not at the superior or inferior ROIs. The T2 value variation for the OA group during loading was lower than that of the healthy group (p=0.016<0.025).

The T2 recovery ratio was presented in this study as a new variable. The findings indicated the T2 recovery ratio of the OA group was significantly lower than the healthy group (p=0.042<0.05) in the patellar cartilage middle ROI. It suggests that the OA cartilage had weaker ability to restore its original status after off-loading than healthy cartilage.

This study examined the glycosaminoglycan (GAG) mass% concentration (relating PG) in human cadaveric patellar cartilages using biochemical assay. Results showed that the GAG mass% concentrations in OA lesion positions were lower than that in comparative healthy positions (p<0.001). MR T2 imaging of healthy and OA cadaver knee joints were performed. Correlations between T2 values and the GAG mass(%) of cadaver patellar cartilage specimens were established. As PG concentration of in-vivo human articular cartilage cannot be directly measured non-invasively, the correlation of cadaveric patellar cartilage may serve as an important bridge between the T2 value and GAG mass% for living human assessment. The findings provide an indirect approach to estimate PG concentration of in-vivo patellar cartilage based on an individual’s cartilage T2 values to evaluate the extent of degradation within cartilage.

This subject specific method is especially suitable for longitudinal evaluation of OA. By position-matched comparison of previous and current T2 images, the GAG mass% variation may be estimated to assess OA progression non-invasively

Keywords: Osteoarthritis; patellar cartilage; MR T2 imaging; in-vivo loading; proteoglycan

Cited Works (12)

Year	Entry
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.
2008	Küpper J. A Novel Measure of in-Vivo Knee Joint Laxity [Master's thesis]. Calgary, AB: University of Calgary; January 2008.
1980	Mow VC, Kuei SC, Lai WM, Armstrong CG. Biphasic creep and stress relaxation of articular cartilage in compression: theory and experiments. J Biomech Eng. February 1980;102(1):73-84.
1994	Roughley PJ, Lee ER. Cartilage proteoglycans: structure and potential functions. Microsc Res Tech. August 1, 1994;28(5):385-397.
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.
1986	Bland JM, Altman DG. Statistical methods for assessing agreement between two methods of clinical measurement. Lancet. February 8, 1986;327(8476):307-310.
2009	Robu I. In Vivo Investigation of Patellofemoral Joint Characteristics Under Loading [Master's thesis]. Calgary, AB: University of Calgary; 2009.
1980	Woo SL-Y, Simon BR, Kuei SC, Akeson WH. Quasi-linear viscoelastic properties of normal articular cartilage. J Biomech Eng. May 1980;102(2):85-90.
2009	Natoli RM, Responte DJ, Lu BY, Athanasiou KA. Effects of multiple chondroitinase ABC applications on tissue engineered articular cartilage. J Orthop Res. July 2009;27(7):949-956.
1986	Farndale RW, Buttle DJ, Barrett AJ. Improved quantitation and discrimination of sulphated glycosaminoglycans by use of dimethylmethylene blue. Biochim Biophys Acta. September 4, 1986;883(2):173-177.
2002	Elliott DM, Narmoneva DA, Setton LA. Direct measurement of the Poisson’s ratio of human patella cartilage in tension. J Biomech Eng. April 2002;124(2):223-228.
1982	Farndale RW, Sayers CA, Barrett AJ. A direct spectrophotometric microassay for sulfated glycosaminoglycans in cartilage cultures. Connect Tissue Res. 1982;9(4):247-248.