title: High-frequency and low-magnitude whole body vibration with rest days is more effective in improving skeletal micro-morphology and biomechanical properties in ovariectomised rodents.
abstract: We explored the optimal regime in preventing or treating bone loss, using ovariectomised rodents loaded by mechanical stimuli with rest days during the loading cycle. Eighty-four Sprague-Dawley rats, aged 6 months, were randomly divided into 7 groups after bilateral ovariectomy. Mechanical vibration with 1-day rest (ML1R), with 3-day rest (ML3R), with 5-day rest (ML5R), with 7-day rest (ML7R), daily loading (DL), comparing the ovariectomised group (OVX) with baseline (BCL) measurements. After a recovery of one week, all the rodents were loaded daily by whole body vibration at 35 Hz and 0.25 g for 15 minutes. Eight weeks later, a three-point bending test of the radius and micro-CT scanning of the femoral head were performed after animal sacrifice. Large improvements in biomechanical properties occurred in all the experimental groups for failure load, elastic modulus and deflection, while a significantly enhanced efficacy was detected in ML7R compared with daily loading (p<0.05). In micro-CT scanning, bone volume fraction, trabecular thickness, number and separation were improved by the regime in all experimental groups, while ML7R showed a significant improvement over daily loading (p<0.05). Early bone loss in human subjects may be improved by high-frequency and low-magnitude whole body vibration with rest days or daily stimuli. Mechanical stimulus with a 7-day rest was more effective in improving biomechanical properties and micro-morphology compared with daily loading. This may have clinical implications in relation to the prevention and treatment of hip fractures, and in postoperative management following hip arthroplasty.
authors.affiliation: Department of Orthopaedics, First Hospital of Jilin University, Changchun, Jilin Province, China.
authors.forename: Renshi
authors.initials: R
authors.lastname: Ma
authors.forename: Dong
authors.initials: D
authors.lastname: Zhu
authors.forename: He
authors.initials: H
authors.lastname: Gong
authors.forename: Guishan
authors.initials: G
authors.lastname: Gu
authors.forename: Xu
authors.initials: X
authors.lastname: Huang
authors.forename: Jia zi
authors.initials: Jz
authors.lastname: Gao
authors.forename: Xizheng
authors.initials: X
authors.lastname: Zhang
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D001862:Bone Resorption / Q000209:etiology / Q000473:pathology* / Q000517:prevention & control; D004195:Disease Models, Animal; D005260:Female; D005270:Femur Head / Q000473:pathology* / Q000503:physiopathology; D010024:Osteoporosis / Q000209:etiology / Q000473:pathology / Q000517:prevention & control; D010052:Ovariectomy / Q000009:adverse effects*; D011884:Radius / Q000473:pathology* / Q000503:physiopathology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013314:Stress, Mechanical; D014732:Vibration / Q000627:therapeutic use*; D016474:Weight-Bearing