title: Low-intensity pulsed ultrasound enhances early healing of medial collateral ligament injuries in rats.
abstract: OBJECTIVE
  To investigate the effect of low-intensity pulsed ultrasound exposure on the healing of injured medial collateral ligaments.
  
  
  METHODS
  Thirteen male Sprague Dawley rats were used in the study. After surgical transection of the bilateral medial collateral ligaments, the ligament of 1 knee received low-intensity pulsed ultrasound exposure (30 mW/cm2 for 20 minutes daily), whereas no ultrasound was applied to the contralateral knee (control side). Eight rats were killed at 12 days after surgery, and 5 rats were killed at 21 days. The bilateral knees of 5 rats were used for mechanical testing at each of the 2 periods, and 12-day specimens of the remaining 3 rats were prepared for the electron microscopic examination. The knees of 5 additional rats were used to obtain mechanical data of the normal uninjured medial collateral ligament.
  
  
  RESULTS
  On the 12th day, the low-intensity pulsed ultrasound-treated side exhibited significantly superior mechanical properties when compared with the control side in ultimate load, stiffness, and energy absorption (P < .05). However, the treatment did not afford any mechanical advantage when tested on the 21st day. The mean diameter of the fibril was significantly larger on the treatment side than on the control side (P < .05).
  
  
  CONCLUSIONS
  Low-intensity pulsed ultrasound exposure is effective for enhancing the early healing of medial collateral ligament injuries.
authors.affiliation: Department of Orthopaedic Surgery, Kobe University School of Medicine, Hyogo, Japan.
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Takakura
authors.forename: Nobuzo
authors.initials: N
authors.lastname: Matsui
authors.forename: Shinichi
authors.initials: S
authors.lastname: Yoshiya
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Fujioka
authors.forename: Hirotsugu
authors.initials: H
authors.lastname: Muratsu
authors.forename: Masaya
authors.initials: M
authors.lastname: Tsunoda
authors.forename: Masahiro
authors.initials: M
authors.lastname: Kurosaka
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D006614:Hindlimb; D008297:Male; D017888:Medial Collateral Ligament, Knee / Q000293:injuries*; D008854:Microscopy, Electron; D051381:Rats; D017207:Rats, Sprague-Dawley; D013997:Time Factors; D014464:Ultrasonic Therapy; D014945:Wound Healing