title: Effect of transosseous application of low-intensity ultrasound at the tendon graft-bone interface healing: gene expression and histological analysis in rabbits.
abstract: The present study investigates the effect of transosseous low-intensity pulsed ultrasound (LiUS) on the healing at tendon graft-bone interface, in molecular and histological level. The anterior cruciate ligament (ACL) in both knees of 52 New Zealand White rabbits was excised and replaced with the long digital extensor. A custom-made ultrasound transducer was implanted onto the medial tibial condyle, adjacent to the surface of the bone tunnel at both knees of the rabbits. The LiUS-treated right knees received 200-mus bursts of 1 MHz sine waves at a pulse repetition rate of 1 kHz and with 30 mW/cm(2) spatial-average temporal-average intensity for 20 min daily (study group), while the left knee received no LiUS (control group). Thirty-six rabbits were used to perform semiquantitative reverse transcription-polymerase chain reaction (RT-PCR) analysis from both study and control groups for transforming growth factor-beta1 (TGF-beta1), biglycan and collagen I. RT-PCR products showed statistically significant upregulation of biglycan and collagen I gene expression in the study group, while TGF-beta1 gene expression exhibited a bimodal profile. Histological examination performed in 16 rabbits from both groups supported the findings of the molecular analysis, indicating a faster healing rate and a more efficient ligamentization process after ultrasound treatment. These findings suggest that transosseous application of LiUS enhances the healing rate of the tendon graft-bone interface, possibly by affecting the expression levels of genes significant for the tendon to bone healing process.
authors.affiliation: Department of Orthopaedic Surgery & Musculoskeletal Trauma, University Hospital of Larissa, School of Health Sciences, University of Thessaly, 22 Papakiriazi st., Larissa, Greece.
authors.forename: Loukia K
authors.initials: LK
authors.lastname: Papatheodorou
authors.forename: Konstantinos N
authors.initials: KN
authors.lastname: Malizos
authors.forename: Lazaros A
authors.initials: LA
authors.lastname: Poultsides
authors.forename: Michael E
authors.initials: ME
authors.lastname: Hantes
authors.forename: Katerina
authors.initials: K
authors.lastname: Grafanaki
authors.forename: Stamatina
authors.initials: S
authors.lastname: Giannouli
authors.forename: Maria G
authors.initials: MG
authors.lastname: Ioannou
authors.forename: Georgios K
authors.initials: GK
authors.lastname: Koukoulis
authors.forename: Vasilios C
authors.initials: VC
authors.lastname: Protopappas
authors.forename: Dimitrios I
authors.initials: DI
authors.lastname: Fotiadis
authors.forename: Constantinos
authors.initials: C
authors.lastname: Stathopoulos
mesh_terms: D000818:Animals; D000070598:Anterior Cruciate Ligament Injuries; D058578:Biglycan; D024042:Collagen Type I / Q000235:genetics; D016326:Extracellular Matrix Proteins / Q000235:genetics; D008297:Male; D023421:Models, Animal; D011509:Proteoglycans / Q000235:genetics; D011817:Rabbits; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D013710:Tendons / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000637:transplantation*; D013977:Tibia / Q000000981:diagnostic imaging*; D053773:Transforming Growth Factor beta1 / Q000235:genetics; D014182:Transplantation, Autologous; D014464:Ultrasonic Therapy / Q000379:methods*; D014463:Ultrasonography; D015854:Up-Regulation; D014945:Wound Healing
chemical_list: D058578:Biglycan; D024042:Collagen Type I; D016326:Extracellular Matrix Proteins; D011509:Proteoglycans; D053773:Transforming Growth Factor beta1