OBJECTIVETo identify the initial effect of dynamic interspinous implant of Coflex on the treatment of lumbar spinal stenosis.

METHODSA retrospective study of 18 patients who underwent posterior lumbar decompression and fixation with interspinous implant of Coflex between March 2008 and October 2009 was taken to compare the Cobb angel of nature and dynamic position on the segment of Coflex fixation at the time of before and after operation and following time,including 10 males and 8 females with average age of 62.2 years old (54 to 71 years). The symptoms of patients included chronic lower back pain and intermittent claudication and lower extremity numbness. All cases including 17 cases of L4,5 and 1 case of L3,4 were central canal stenosis without obviously segmental instability. Clinical outcomes were evaluated with VAS and ODI.

RESULTSAll patients were followed up from 10 to 18 months with an average of 14.4 months. There did not about internal fixation failure. It was found that postoperative Cobb angel of fixation segment [(12.1 +/- 2.6) degrees] was significantly decreased than preoperative [(14.8 +/- 3.2) degrees] (t = 2.61, P = 0.03). But the Cobb angel [(14.9 +/- 4.1) degrees] increased at final follow-up, even reached the level of before operation (t = 1.39, P = 0.65). The Cobb angle of upper adjacent segment did not obviously change in preoperation, postoperation and final follow-up [(12.1 +/- 2.3) degrees, (12.3 +/- 3.2) degrees, (11.9 +/- 3.0) degrees, respectively]. Dynamic measure showed that Coflex can adequately limit the ROM of extension (t = 4.01, P = 0.001), but the ROM of flexion increased (t = 2.57, P = 0.02). The VAS score in follow-up (2.2 +/- 0.7) was significantly decreased than before operation (4.9 +/- 1.1, t = 2.95, P = 0.02). The ODI score in follow-up [(29.1 +/- 9.0)%] was significantly decreased than before operation [(56.5 +/- 14.2)%, (t = 3.02, P = 0.02)].

CONCLUSIONThe Coflex implanting combined with decompression can get good result clinically, but imaging showed that Coflex can not maintain the relatively kyphosis gained after operation except for extension limitation.