The effects of subfracture impact loading on

the patellofemoral joint in a rabbit model.

Proc. 40th STAPP Car Crash Conference. SAE 962422, 1996.

1st Place in Student Paper Competition

Newberry, WN, Haut,RC.

ABSTRACT:

This study showed that subfracture impact loading to a joint creates stresses in cartilage and bone which can initiate a chronic osteoarthrosis. The magnitude and location of the impact induced stresses are dependent on the orientation and the intensity of loading. Impact loading produced lesions on retro-patellar cartilage and their depths increased as the thickness of subchondral bone increased with time post-impact. Mechanical tests of cartilage indicated significant softening twelve months post-impact. These alterations are similar to those documented clinically as early OA. In vitro impacts of isolated limbs, together with mathematical models, showed that high mean stress generated during impact may help protect joint tissues from acute injury. This study and others are being used to develop stress-based tissue failure criteria for predicting an osteoarthrosis following subfracture impact loading.

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