Objective     To investigate the role of matrix metalloproteinase-13 (MMP-13) in articular cartilage injury by observing the MMP-13 changes in articular cartilage in rat hindlimb after ischemia/reperfusion (IR).      Methods     Wistar rat model of left hindlimb IR was used. Fifty-six rats were randomly divided into sham operation group

8-hour ischemia group

and groups that were reperfused for 3

7

14

30 and 60 d after 8-hour ischemia. Articular cartilages of tibial plateau were taken to study MMP-13 and type Ⅱ col

lagen (COL Ⅱ) by immunohistochemical method (SP). The pathological changes of articular cartilages also were observed.      Results     Cartilage matrix was compact in sham operation group and 8-hour ischemia group. Articular facet became rough

cartilage matrix became looser

and chondrocytes were in disorder gradually after reperfusion

especially on day 30 and 60. MMP-13 of cartilages increased significantly in reperfusion groups (

P

<

0.01)

and peaked on day 14. COL Ⅱ of cartilages decreased progressively and were lower than that in sham operation group and 8-hour ischemia group significantly (

P

<

0.01).      Conclusion     The decrease of COL Ⅱ and the destruction of collagen network structure in articular cartilages resulting from MMP-13 increase could be one very important reason for dissatisfactory recovery of articular functions after replantation of amputated limb.