【Objective】To study the clinical effects of single Coflex interspinous implant on the treatment of degenerative disc disease (DDD). 【Methods】 From June 2008 to December 2009 ninety-two degenerative disc disease patients who were accorded with the entry and removal value were divided into two groups randomly also by considering their desire. 21 cases were treated with single Coflex interspinous implant (Coflex group) and 71 cases with posterior lumbar intervertebral fusion (PLIF group). The hospital stay

operative time

blood loss and complications of all cases were surveyed. Low back pain (LBP) and leg pain at preoperative and final follow-up were evaluated according to VAS scales

and the Oswestry Disability Index (ODI) was recorded to evaluate the function. Flexion-extension radiographs were taken separately and range of motion (ROM) of the instrumented level and upper adjacent were measured. We compared the hospital stay

operative time

blood loss between the two groups. At the same time

VAS scales of LBP and leg pain

ODI

ROM of the instrumented level and upper adjacent were also compared in and between groups. 【Results】Hospital stay

operative time and blood loss in the Coflex group were significantly less than those in the group of PLIF (P < 0.01). VAS scales of LBP and leg pain

ODI of the final follow-up were significantly lower than preoperative in both groups (P < 0.01). Between the two groups

however

there were no significant differences neither at preoperative or final follow-up (P > 0.05). It achieved bone fusion in the group of PLIF at the final follow-up

although ROM of the instrumented level at the final follow-up in the group of Coflex was similar to the preoperative(P = 0.70). It was significantly higher in terms of ROM of the instrumented level at the final follow-up in the group of Coflex(P < 0.01)

but no significant differences were found in terms of ROM at preoperative between groups(P = 0.50). ROM at the upper adjacent level at the final follow-up in the group of Coflex was similar to the preoperative(P = 0.63)

whereas that in group of PLIF was markedly increased at the final follow-up(P = 0.02)

compared with preoperative. It was significantly higher in terms of ROM of segment of adjacent upper operation at the final follow-up in the group of PLIF(P = 0.02)

though no significant differences were found in terms of ROM at preoperative between groups(P = 0.61).【Conclusion】 There is no significant differences between single Coflex interspinous implant treated for DDD and posterior interbody fusion in improving clinical symptoms. But hospital stay

operative time

blood loss were less in the single Coflex interspinous implant groups than those in posterior interbody fusion groups. Coflex interspinous implant not only provides control but not limited activity of the surgery segment

but also effectively reduces the activity of the adjacent segment.