Evaluation of fracture toughness of cartilage by micropenetration

N. K. Simha, C. S. Carlson, J. L. Lewis

Research output: Contribution to journalArticlepeer-review

98 Scopus citations


Failure properties of cartilage are important in injury repair and disease, but few methods exist for measuring these properties, especially in small animals. To meet this need, a new indentation/penetration method for measuring fracture toughness of cartilage is proposed. During indentation, a conical tip is displaced into the surface of the cartilage, causing first a non-penetrating indentation, and then a penetration into the tissue. The method assumes that tissue penetration occurs during periods of "rapid work", which are identified from a curve of work rate vs. time. Total penetration depth is determined by summing the displacement during these periods. Fracture work is the work that occurs during "rapid work", or penetration, and fracture toughness defined as the fracture work divided by one-half the penetrated surface area of the indenting tip. The method was validated by indentation testing of bovine cartilage. Penetrating indentations with a conical tip were performed in bovine patellar cartilage and depth of penetration and fracture toughness predicted. For comparison with the indentation data, depth of penetration was measured in histological sections. These measurements agreed well with the predicted depth. Predicted fracture toughness also agreed with values measured via a macroscopic test. This newly described method has promise as a general method for measuring fracture toughness in cartilage, particularly in small animals, since penetrating tips with small tip radius can be manufactured and penetration may be accomplished in cartilage of minimal thickness.

Original languageEnglish (US)
Pages (from-to)631-639
Number of pages9
JournalJournal of Materials Science: Materials in Medicine
Issue number5
StatePublished - May 2004

Bibliographical note

Funding Information:
This work was supported primarily by the MRSEC Program of the National Science Foundation under Award Number DMR-9809364, and partially by the Catharine Mills Davis Endowment to the Department of Orthop aedic Surgery and a grant from the NIH (AR-14099). We are grateful to Anne Undersander, who prepared the histology sections.


Dive into the research topics of 'Evaluation of fracture toughness of cartilage by micropenetration'. Together they form a unique fingerprint.

Cite this