The Clinical Observation Of The Forepart-expansible Cage For Treating Lumbar Instability

Objective:Retrospective analysis of 83 cases of lumbar instability treated with micro endoscopic discectomy(MED)and posterior lumbar interbody fusion using the forepart-expansible cage.Sum up the,explore the clinical therapeutic effect,to provide the guidance for the clinical application of the forepart-expansible cage.Method:Retrospective analysis of 83 cases of lumbar instability treated with micro endoscopic discectomy(MED)and posterior lumbar interbody fusion using the forepart-expansible cage from January 2013 to January 2015 in The First Affiliated Hospital of Zhengzhou University.There were 43 males and 40 females,with an average age of 59 years(46-76 years).There were 145 segmental lesions: L1/2 6 lesions,L2/3 8 lesions,L3/4 31 lesions,L4/5 66 lesions,L5/S1 34 lesions.The following indicators of each segmental lesions were measured in lumbar lateral X-ray images: the anterior intervertebral heights(a),the anterior intervertebral concave region heights(b).All the cases were implanted into the anterior end of the intervertebral space with two forepart-expansible cages,postoperative CT was performed to confirm fusion.analyze the implanted location and clinical effect of different types with the forepart-expansible cage.Result:There were 209 segmental lesions in 83 cases of lumbar instability.All the patients treated with micro endoscopic discectomy(MED)and posterior lumbar interbody fusion using the forepart-expansible cage.a>b,accounting for 89%(129/145),a=b accounting for 10.3%(15/145),a<b,accounting for 0.7%(1/145).Paired t test of each segment data,a > b in L3/L4,L4/L5 and L5/S1 segments was statistically significant.Follow up for 3--24 months.According to the Japan Department of orthopedics Association(JOA),improvement rate was 83.5%±13.0%.According to Suk criterion,solid union occurred in 60 cases(41.3%)and probable union in 85 cases(58.7%).Subsidence of two cages were found,the total subsidence rate was 1.4%(2/145).Displacement of one cage were found,the total translocation rate was 0.7%(1/145).Conclusion:When the forepart-expansible cage placed in front of vertebral body,aligned with anterior edge of vertebral body,its wedge shaped structure is in good agreement with the most of the front disc endplate high to low(a,b)structure,forepart-expansible cage and vertebral endplate can form stable "surface contact",and stability is difficult affected by lumbar spine activity.Compared with the placement of forepart-expansible cage in the middle part of the intervertebral space,it can achieve better clinical effect and reduce the risk of complications such as the cage displacement and so on.