The Clinical Study Of The Modified Thoracolumbar Posterior Midline Approach

Objective1.To compare the clinical effect of the posterior lumbar modified midline approach and the traditional approach for the treatment of lumbar degenerative disease,and discuss clinical application value of the former.2.To analysis the effects of pedicle screw fixation via the injured vertebra and across the injured vertebra on the recovery of the middle height of the fractured vertebral body for thoracic or lumbar fractures,and discuss clinical significance.Methods1.From April 2014 to December 2015,165 patients with single segment lumbar degenerative disease were treated with posterior lumbar interbody fusion(PLIF).They were divided into two groups according to different surgical approaches.The modified group(n=70)were treated with modified mini-open PLIF which retains the attachment area of thoracolumbar fascia and erector aponeurosis at the supraspinal ligament and makes a vertical incision along the posterior layer and erector aponeurosis at 1.5 to 2.0 cm lateral to the midline,and the remaining steps are the same with the traditional approach.Whereas the traditional group(n=95)with traditional open PLIF.The surgical incision length,blood loss,postoperative drainage,use of analgesics,visual analogue scale(VAS)and oswestry disability index(ODI)were compared between modified group and conventional group.After pre-and postoperative cross sectional areas(CSAs)of the paraspinal muscle were measured at the L3/4,L4/5 and L5/S1 levels using a 3-T magnetic resonance(MR)scanner by Picture Archiving and Communication System(PACS),the atrophy ratios of the paraspinal muscle were compared between two groups.The paraspinal muscle atrophy after surgery was determined as the ratio of postoperative CSA to preoperative CSA(atrophy ratio).Then the clinical effect of the two groups was compared,and the clinical value of the modified approach was discussed.2.From January 2011 to December 2012,67 patients with thoracolumbar type A spinal injuries were treated with short-segment fixation via the injured vertebra and across the injured vertebra.36 males and 31 females with a mean age of 37.8±7.5 years(range,17?52 years),a mean follow-up of 26 months(range,18-40 months)had complete records.The types were T11?L2 single vertebral fractures(AOspine type A)without serious neurologic deficits(ASIA typeD?E).All patients were divided into two groups according to different instrumentation,group A(n=37)were treated with fixation via the injured vertebra,whereas group B(n=30)skipping the injured vertebra.Using the PACS imaging system to measure the anterior(Ha),middle(Hm)and posterior(Hp)height of the fractured vertebral body,and the kyphotic Cobb angle on lateral X-ray films at preoperative,postoperative 1 week and final follow-up,then compression ratio of Ha and Hm were calculated to observe the recovery of the middle height of the fractured vertebral body.Results1.There was no significant difference in gender,age,fusion segment and hospitalization day(P>0.05).Compared with the traditional group,the shorter surgical incision lengths,less blood loss and postoperative drainage,quicker recovery and less use of analgesics were recorded in modified group(P<0.05).The atrophy ratios of paraspinal muscle at the L3-L4,L4-L5 and L5-S1 levels were significantly higher in the modified group than in the conventional PLIF group(P<0.01).However,the modified group needed significantly longer operation time.There were no significant differences in VAS and ODI scores between the two groups before surgery(P>0.05).Postoperative VAS and ODI scores were significantly reduced than preoperative scores both the groups(P<0.001),but the modified group were obviously lower(P<0.05).At final follow-up,they showed no significant differences in VAS and ODI scores(P>0.05).2.Regardless of fixation via or across the injured vertebra,postoperative compression ratio of Ha or Hm and Cobb angle were significantly decreased compared with preoperation(P<0.05).At preoperative,1 week after operation and final follow-up,compression ratio of Hm was 44.8±10.3%,31.6±7.1%and 31.3 ± 6.8%in group A;likewise compression ratio of Hm was 38.6±8.3%,32.0±8.4%and 31.7±8.6%in group B.In terms of Hm,there were still about 30%compressive residual that was not recovered in two groups.Conclusions1.The modified approach and traditional approach can both obtain satisfactory clinical effect for the treatment of lumbar degenerative diseases.However,the modified approach has the advantages of shorter incision,less trauma,less postoperative pain and quicker recovery.What's more,the learning curve is shorter,and the operation is more simple.2.Both above two fixations can recover the height of the fractured vertebral body and kyphosis Cobb angle,but there were all obvious compressive residual for Hm at postoperation,which play an important role in the disc degeneration,narrowing of intervertebral space,spinal imbalanced alignment and chronic low back pain.