title: Achilles tendon healing: a correlation between functional and mechanical performance in the rat.
abstract: The pathogenesis and treatment of rupture of the Achilles tendon remain a source of controversy. This study presents the results of a biomechanical, functional, and morphological evaluation of a group of rats that had division and repair of the Achilles tendon. A total of 46 rats were used: 18 for biomechanical testing, 18 for functional evaluation, and 10 for histology. Morphological examination revealed an early inflammatory response with loose connective tissue formation that was replaced gradually by fibroblasts and a collagenous matrix. The functional evaluation (Achilles functional index [AFI]) was made from measurements of the hind pawprints of walking rats. Division and repair of the Achilles tendon produced a significant functional impairment (mean [+/- SEM] AFI = -87 +/- 8; p < 0.001), which gradually improved with healing time. The load to failure for the repaired tendons consistently improved with healing time, in a manner similar to the functional recovery. The average deformation (repair/control) varied considerably and was not related to healing time. The stiffness of the repaired tendons increased with healing time and was 60% of the corresponding control side by day 15. The major finding of this study was a strong correlation between the AFI and the failure load of the healing tendon-bone constructs (250-300 g group, r = 0.97, p < 0.001; 325-375 g group, r = 0.96, p < 0.001).
authors.affiliation: Division of Orthopaedic Surgery, Duke University Medical Center, Durham, NC 27710.
authors.forename: T M
authors.initials: TM
authors.lastname: Best
authors.forename: A
authors.initials: A
authors.lastname: Collins
authors.forename: E G
authors.initials: EG
authors.lastname: Lilly
authors.forename: A V
authors.initials: AV
authors.lastname: Seaber
authors.forename: R
authors.initials: R
authors.lastname: Goldner
authors.forename: G A
authors.initials: GA
authors.lastname: Murrell
mesh_terms: D000125:Achilles Tendon / Q000293:injuries* / Q000473:pathology / Q000503:physiopathology; D000818:Animals; D001696:Biomechanical Phenomena; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D012044:Regression Analysis; D013997:Time Factors; D014945:Wound Healing