ENFORCED EXERCISE SOFTENS AND HELPS LIMIT HISTOLOGICAL CHANGES IN RETROPATELLAR CARTILAGE AFTER BLUNT TRAUMA TO THE RABBIT PATELLO-FEMORAL JOINT.

Journal of Orthopaedic Research

In press

Weaver,BT, Ewers,BJ, Haut,RC

ABSTRACT:

Our laboratory has developed an animal model to study some of the factors leading to chronic disease processes in an impacted joint. Acutely, earlier studies have shown that blunt trauma will generate surface lesions on retro-patellar cartilage. While at 36 months post-trauma the cartilage is significantly thinned and softened versus the un-impacted limb, the model otherwise shows few signs of an advanced pathology such as osteoarthrosis. The current study hypothesized that the disease process would be accelerated in the patello-femoral joint if regular post-trauma exercise were mitigated in the model. The study involved 2 groups of animals with post-trauma exercise and 2 groups with cage-activity. The animals were sacrificed at 12 and 24 months. Mechanical and histological analyses were performed on retro-patellar cartilage from each group. While the impacted retro-patellar cartilage was mechanically softened at each time point in the treadmill-exercised groups, histological analyses indicated that the cartilage was more degraded in the cage-activity groups. This study suggested that regular post-trauma exercise program was beneficial to the health of traumatized retro-patellar cartilage at 24 months. The benefit of regular exercise in this joint trauma model may directly relate to the stability of the joint, as no ligament ruptures or osteochondral fractures have been reported in this model.

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