Effects of Low-magnitude Whole Body Vibration (WBV) on Knee Osteoarthritis in Rabbits

Objective To determine the effects of low-magnitude whole body vibration (WBV) on the structure and function of subchondral trabecular bones, cartilage degradation, bone/cartilage turnover, and osteoarthritis (OA) joint function. Methods Knee osteoarthritis model was established in 96 rabbits through left anterior cruciate ligament transaction (ACLT). The rabbits were randomly divided into six groups: ACLT control group, WBV+ACLT group (five subgroups, each comprising 16 rabbits receiving 5 Hz, 10 Hz, 20 Hz, 30 Hz and 40 Hz WBV, respectively, with 2-4 mm amplitude for 40 min/d and 5 d/week over a period of 8 weeks). Joint function was tested via weight-bearing asymmetry. The microarchitecture of subchondral trabecular bones was examined using vivo micro-computed tomography (micro-CT). Cartilage samples from knee joints were taken for gross morphology and histology examinations. Serum samples were taken to detect cartilage oligomeric matrix protein (COMP), C-terminal telopeptide of type Ⅰ collagen (CTX)-Ⅰ and urine CTX-Ⅱ. Results Knee joint pain decreased with 10 Hz （P<0.05） and 20 Hz WBV treatment （P<0.05）, but increased with 40 Hz treatment (P<0.05). The micro-CT results showed that articular cartilage increased first, peaked at 20 Hz, and then decreased （P<0.05）. With increased frequency of WBV, the trabecular number, subchondral bone thickness and bone volume fraction increased, serum CTX-Ⅰ decreased, COMP and CTX-Ⅱ increased, especially at 20 Hz (P<0.05). Conclusion Lower frequency (20 Hz) WBV can improve bone microstructure, increase bone turnover, delay cartilage degeneration and improve limb function of rabbits with OA.