title: A Novel In Vivo Joint Loading System to Investigate the Effect of Daily Mechanical Load on a Healing Anterior Cruciate Ligament Reconstruction.
abstract: We designed and validated a novel knee joint fixation/distraction system to study tendon-to-bone healing in an in vivo rat model of anterior cruciate ligament (ACL) reconstruction. The system uses an external fixator to apply a cyclic distraction of the knee joint while monitoring the resultant force developed across the joint, thus providing a temporal indication of structural changes during the healing process of the bone-tendon-bone reconstruction. The validation was performed using an optical kinematic tracking system to determine the local displacement of the knee. The average system compliance was determined to be 42.4 +/- 8.8 mum/N with a coefficient of variation of 20.7%. The compliance was used to obtain a best fit correction factor which brought the total root mean square error of knee joint distraction to within 179 mum (16.1%) of the applied distraction. We performed a pilot study using 15 rats that had ACL reconstructions using a flexor digitorum longus tendon autograft and found that the animals tolerated the indwelling fixator and daily anesthesia over a 10 day loading protocol. Our knee joint fixation/distraction system provides a valuable tool to study how mechanical stimuli affect in vivo bone-tendon-bone healing.
authors.affiliation: Laboratory for Soft Tissue Research, Hospital for Special Surgery, 535 East 70th Street, New York, NY 10021; Department of Biomedical Engineering, City College of New York, New York, NY.
authors.forename: Mark
authors.initials: M
authors.lastname: Stasiak
authors.forename: Carl
authors.initials: C
authors.lastname: Imhauser
authors.forename: Jonathan
authors.initials: J
authors.lastname: Packer
authors.forename: Asheesh
authors.initials: A
authors.lastname: Bedi
authors.forename: Robert
authors.initials: R
authors.lastname: Brophy
authors.forename: David
authors.initials: D
authors.lastname: Kovacevic
authors.forename: Kent
authors.initials: K
authors.lastname: Jackson
authors.forename: Xiang-Hua
authors.initials: XH
authors.lastname: Deng
authors.forename: Scott
authors.initials: S
authors.lastname: Rodeo
authors.forename: Peter
authors.initials: P
authors.lastname: Torzilli