ABSTRACT
BACKGROUND: Anterior interbody fusion has previously been demonstrated to increase neuroforaminal height in a cadaveric model using cages. No prior study has prospectively assessed the relative change in magnetic resonance imaging (MRI) demonstrated neuroforaminal dimensions at the index and supradjacent levels, after anterior interbody fusion with a corticocancellous allograft in a series of patients without posterior decompression. The objective of this study was to determine how much foraminal dimension can be increased with indirect foraminal decompression alone via anterior interbody fusion, and to determine the effect of anterior lumbar interbody fusion on the dimensions of the supradjacent neuroforamina. METHODS: A prospective study comparing pre- and postoperative neuroforaminal dimensions on MRI scan among 26 consecutive patients undergoing anterior lumbar interbody fusion without posterior decompression was performed. We studies 26 consecutive patients (50 index levels) that had undergone anterior interbody fusion followed by posterior pedicle screw fixation without distraction or foraminotomy. We used preoperative and postoperative MRI imaging to assess the foraminal dimensions at each operated level on which the lumbar spine had been operated. The relative indirect foraminal decompression achieved was calculated. The foraminal dimension of the 26 supradjacent untreated levels was measured pre- and postoperatively to serve as a control and to determine any effects after anterior interbody fusion. RESULTS: In this study, 8 patients underwent 1 level fusion (L5-S1), 12 patients had 2 levels (L4-S1) and 6 patients had 3 levels (L3-S1). The average increase in foraminal dimension was 43.3% (p 0.05). CONCLUSIONS: Anterior interbody fusion with a coriticocancellous allograft can significantly increase neuroforaminal dimension even in the absence of formal posterior distraction or foraminotomy; anterior interbody fusion with a coriticocancellous allograft has little effect on supradjacent neuroforaminal dimensions.
Subject(s)
Female , Humans , Male , Intervertebral Disc Degeneration/diagnosis , Lumbar Vertebrae , Magnetic Resonance Imaging , Prospective Studies , Spinal FusionABSTRACT
Objective To establish L4 vertebrae burst fractures and take a biomechanical test of different internal fixations so as to discuss the significance of internal fixation using short-segment plus Index-level screws in treatment of low lumbar burst fractures.Methods Ten fresh human lumbosacral vertebrae specimens were used to establish models of L4 vertebrae burst fractures by corpectomy and partial removal of ligament.Thereafter,the biomechanical test was performed in order as below:longsegment fixation,short-segment fixation and short-segment construction plus Index-level screw fixation.Differences of range of motion (ROM) of the lumbar after three different internal fixations were compared.Results Compared with short-segment fixation,short-segment plus Index-level screw fixation showed that ROM of the lumbar was decreased in front flexion,axial rotation and lateral bending (P ＜ 0.05),but stability was improved and ROM of lumbar was decreased by 32.7％ in back extension (P ＞ 0.05).Conclusions Compared with short-segment fixation,the short-segment plus Index-level screw fixation can increase initial lumbar stability by average 32.5％ in treatment of low lumbar burst fractures.In the meantime,short-segment plus Index-level screw fixation provides larger ROM of the lumbar than the long-segment fixation.