The Feasibility And Efficacy Of Additional Bone Grafting Around The Cage In Anterior Approach For Thoracolumbar Fracture

Abstract:Objective: To evaluate the feasibility and efficacy of additional bonegrafting around the cage in anterior approach for the treatment ofthoracolumbar burst fracture. Methods: From March2005to March2011，167patients(including105male,62female patients)with thoracolumbar fracturewere treated with anterior approach in the department of spinal surgery ofaffiliated hospital of Luzhou Medical College. The inclusion criteria were (1)patients without adjacent vertebral fracture,(2) no posterior ligament complexinjury,(3) no obvious osteoporosis,(4) delayed thoracolumbar fractures withpost-traumatic kyphosis or incomplete paralysis which necessitated anteriorsurgery and (5) patients needing reversion surgery after failures of posteriorinstrumentation. Exclusion criteria included patients had (1) compressionfracture of adjacent vertebrae which precluding stable anterior instrumentation,(2) posterior ligamentous complex injury,(3) less than50%encroachment ofspinal canal or intact neurological deficits,(4) less than half loss of height ofvertebral body and (5) posterior facet joint dislocation or interlocking. Allpatients were evaluated with x-ray and3dimensional CT scans preoperativelyand3,6, l2months postoperatively and annually thereafter to observe thefusion status graft and to measure the Kyphotic Cobb angle, height of fracturedvertebrae and spinal stenotic rate. The neurological functions were measured by Frankel grade. The modified Brantigan grade was used to assess the fusion rate.SPSS17.0statistic software was used for statistic analysis. Quantitativeparameters were analyzed with t test and the P value was set at0.05.Results: All patients were successfully managed with this technique. Nodeterioration of neurological functions, CSF leakage, thoracic hematoma, deepvein thrombosis happened postoperatively. All patients received additionalbone graft in the adjacent disc spaces and lateral side of cage.116patientsincluding74male and42female with the average of42.5years (18to64years),were followed for2.2years (1-4.5years). They included65cases of freshthoracolumbar fractures (<21d),26cases of delayed thoracolumbar fracturesand25cases of reversion surgery after failure of posterior approach. X-ray afterone week postoperatively revealed no bones shift into the spinal canal, thepleural cavity (if present of pleural rupture). No obvious hematoma formedaround the Cage. At3months’ follow-up,1-2mm of bright line around theCage (titanium nets/artificial bone) was seen and no fragment encroachment ofspinal canal was found in CT scans. At6months’ follow-up, X-ray did notshow heterotopic ossification formation in82patients. CT scan showed a thinlayer bone trabeculae formed in41cases between Cage and surrounding area.At one year after surgery,54patients achieved grade E fusion,23grade Dfusions and27grade C fusions. But in12patients who received nano-artificialcage grafting, only few trabeculae formed between the cage and the endplatesand a1-2mm radiolucent line formed. Appositions of cages were found in3 cases with titanium mesh and4cases with artificial cage grafting (in sagittal orcoronal were less than10otilting), but no obvious scoliosis or kyphosisoccurred at last follow-up. One to two Frankel grades of improvement in spinalcord function were documented for all patients with incomplete paralysis. Themeans height of fractured vertebrae was31.6±4.8mm before surgery,39.3±3.7mm at1week after surgery and38.6±3.6mm at final follow up and themean loss of correction was0.8mm．Subsidence of cages was found in4cases(3.3%)(more than2mm of height loss). The average Cobb angle was17.8°preoperatively,-2o-15opostoperatively, and8.4oat last follow-up.Compared with the preoperative value, significant improvement was foundpostoperatively(t=4.65, P＜0.001）. CT scan showed the stenosis was44%preoperatively,0-18%at discharge and10％at final follow up in32patients.Compared with the preoperative value, significant improvement was found atlast follow-up(t=3.42, P＜0.001）. During the follow-up, no dislocation of cage,heterotopic ossification and internal fixation failure and neurologicaldeterioration occurred. Conclusions: Anterior approach with additional bonegrafting around Cage for thoracolumbar burst fracture can reduce gap aroundthe Cage, and increases contact area between the cage and surrounding bonetissues, and thus improve the incorporation of the grafting material and reducethe risk of sinking, collapse and tilt of cage. It also increases the mechanicalstrength of spine and reduces the risk of implant failure.