Acceleration of tendon–bone healing of anterior cruciate ligament graft using intermittent negative pressure in rabbits

BACKGROUND The purpose of this study was to test effects of negative pressure on tendon-bone healing after reconstruction of anterior cruciate ligament (ACL) in rabbits. METHODS Hind legs of 24 New Zealand White rabbits were randomly selected as negative pressure group and the contralateral hind legs as control. Reconstruction of the ACL was done. Joints of the negative pressure side were placed with drainage tubes connecting the micro-negative pressure aspirator. Control side was placed with ordinary drainage tubes. Drainage tubes on both sides were removed at the same time 5 days after operation. After 6 weeks, joint fluid was drawn to detect the expression levels of interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α); at the same time, femur-ligament-tibia complex was obtained to determine tendon graft tension and to observe the histomorphology, blood vessels of the tendon-bone interface, and expression of vascular endothelial growth factor (VEGF). RESULTS The maximum load breakage of tendon graft was significantly greater in the negative pressure group than in the control group (P < 0.05). Histological studies of the tendon-bone interface found that there was more new bone formation containing chondroid cells and aligned connective tissue in the negative pressure group than in the control group. Expression of VEGF was higher in the negative pressure group than in the control group (P < 0.01). Content of IL-1β and TNF-α in synovial fluid is lower in the negative pressure group than in the control group (P < 0.01). CONCLUSIONS Intermittent negative pressure plays an active role in tendon-bone healing and creeping substitution of ACL reconstruction in the rabbits.