Subfracture insult to a knee joint causes

alterations in the bone and in the

functional stiffness of overlying cartilage.

J. Orthopaedic Research 15(3):450-455, 1997.

Newberry, WN, Haut,RC.

ABSTRACT:

Current criteria used by the automotive industry for predicting joint injury are based on fracture of bone, but clinical studies suggest chronic diseases such as OA can occur from a single blunt insult without bone fracture. In the current study blunt insults were delivered to rabbit patello-femoral joints without producing bone fracture. Biomechanical and histological studies were performed on joint tissues at various post-insult times. Functional integrity of retro-patellar cartilage on the lateral facet was measured with mechanical indentation experiments. The thickness of the subchondral bone was measured from histological sections. Impacts produced surface lesions on retro-patellar cartilage. The thickness of subchondral bone in representative animals tended to increase with time post-insult, and exhibited significant thickening at 12 months. The overlying cartilage showed signs of degeneration. However, mechanical stiffness of the cartilage did not change until one year post-insult.

Orthopaedic Biomechanics Laboratories,

College of Osteopathic Medicine,

Michigan State University,

East Lansing, Michigan 48824

Please address correspondence to:

Roger C. Haut, Ph.D.,

Orthopaedic Biomechanics Laboratory,

College of Osteopathic Medicine,

A414 East Fee Hall,

Michigan State University,

East Lansing, MI 48824,

Tel: (517)355-0320,

Fax: (517)353-0789,

E-mail: haut@msu.edu