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A Rat Tibial Growth Plate Injury Model to Characterize Repair Mechanisms and Evaluate Growth Plate Regeneration Strategies
Published on: July 4, 2017
Tendon to bone tunnel healing--a study on the time-dependent changes in biomechanics, bone remodeling, and histology
Geir Aasmund Hjorthaug1, Jan Erik Madsen, Lars Nordsletten
1Department of Orthopaedic Surgery, Division of Surgery and Clinical Neuroscience, Oslo University Hospital, Kirkeveien 166, N-0450, Oslo, Norway; Institute of Clinical Medicine, University of Oslo, Oslo, Norway; Institute for Surgical Research, Oslo University Hospital, Oslo, Norway.
Abstract:
Tendons and ligaments attach to bone through a transitional connective tissue with complex biomechanical properties. This unique tissue is not regenerated during healing, and surgical reattachment therefore often fails. The present study was designed to evaluate tendon healing in a bone tunnel and to evaluate the utilized rat model. Wistar rats (n = 61) were operated with the Achilles tendon through a bone tunnel in the distal tibia. Healing was evaluated at 2, 3, 4, and 12 weeks by biomechanical testing, bone mineral density and histology. After 2 weeks median (interquartile range) pull-out force was 2.2 N (1.9). The pull-out force increased chronologically, by 12 weeks fivefold to 11.2 N (11.4). Energy absorption, stiffness, and bone mineral density increased similarly. The histological analyses showed inflammation at early stages with increasing callus by time. Our data showed a slow healing response the first 4 weeks followed by an accelerated healing period, favoring that most of the gain in mechanical strength occurred later than 4 weeks postoperatively. These findings support the concern of a vulnerable tendon bone tunnel interface in the early stages of healing.
