Patellar tendon augmentation after removal of its

central third limits joint tissue changes.

J. Orthopaedic Research 17:28-36, 1999.

Atkinson, PJ, Oyen-Tiesma, M, Zukosky,

DK, DeCamp, CE, MacKenzie, CD, Haut, RC.

Abstract:

The central third of the patellar tendon is commonly used to reconstruct the injured ACL. Some studies have noted changes in joint tissues following this procedure. It has been postulated that these changes may be associated with increased stress on the remaining tendon following graft harvest. In the current study the central third of the patellar tendon was excised in three groups of rabbits. The central tendon defects in two of the three groups of animals were fitted with different augmentation devices to limit stress on the host tendon. All animals followed a daily treadmill exercise regime for 12 weeks. Biomechanical testing of the tendon revealed that in non-augmented animals the cross-sectional area and length of the patellar tendon significantly increased 112% and 16%, respectively. There was histological evidence of host tendon remodeling throughout the cross section and extensive fibrosis in the infrapatellar fat pad. Tendon augmentation significantly reduced these changes, proportional to the stiffness of augmentation used. Animals with augmentation devices retained tendon dimensions near those of the contralateral unoperated tendon, and tendon remodeling occurred only in the defect area. Augmented animals exhibited little to no fat pad fibrosis. Structural properties of augmented and non-augmented tendons were similar despite the size differences, indicating higher tissue quality in augmented animals. This study suggests that knee joint complications may be directly related to increased stress in the healing host tendon, and these complications may be prevented by limiting this stress.

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