Fiberoptic microindentation technique for early osteoarthritis diagnosis: an in vitro study on human cartilage
In this study, the capability of a fiber optic microindenter sensor to discriminate between healthy and slightly degenerated human articular cartilage samples is demonstrated. The purely optical indenter sensor is characterized by extremely reduced dimensions (0.125 mm in diameter and 27 mm in length) in comparison to existing indenter probes offering advantages for endoscopic deployment. The indenter sensor is intended to assist the surgeon in the identification of damaged articular cartilage. From each of seven specimens of human tibia plateau three samples showing different Outerbridge grading were extracted. On each sample stress-relaxation measurements were performed with eight indentation steps, each step being 40 μm and the relaxation of the material was observed for 240 s after each step. A viscoelastic model was used to fit the relaxation and to extract the characteristic parameters according to the model. A highly significant difference in stiffness (p value <0.01) was observed between the native (grade 0) and early diseased (grade 1) human cartilage samples demonstrating the potential of the fiber optic indenter for the diagnosis of cartilage breakdown.
KeywordsFiber Bragg grating Osteoarthritis Indentation Cartilage biomechanics
The research was funded by the Deutsche Forschungsgemeinschaft (DFG) (grants RO 4145/4-1, CS 409/2-1 and AS 150/10.1). The authors thanks Rolf Kuttler for technical support, as well as Sabrina Wagner, Carmen Marthen and Jutta Tübel of the University Hospital Klinikum rechts der Isar for the Outerbridge grading of the human samples.
Compliance with ethical standards
Conflict of interests
The authors declare that no conflict of interest exists.
All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.
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