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

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.

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.

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).

Lower frequency (20 Hz) WBV can improve bone microstructure, increase bone turnover, delay cartilage degeneration and improve limb function of rabbits with OA.