Biomechanical Stability Evaluation And Clinical Research Of Unilateral Versus Bilateral Pedicle Screw Fixation Plus Interbody Fusion Cage

Objective:Current clinical lumbar disc herniation on the surgical treatment of common surgical procedures are a laminectomy or semilaminectomy and discectomy with bilateral pedicle screw fixation fusion. This technique to a large extent changed the lumbar segment biomechanical characteristics, trauma, and the high cost of more controversial. Indications of how strictly to reduce the removal of the scope of the lowest possible number of fixed segments in order to reduce the vertebral body adjacent to a fixed secondary degeneration, has attracted clinical attention. The subject of a new surgical methods, that is, "the experimental group improved PLIF law" from biomechanics experimental point of view, further comparison of different operations on the lumbar spine strength, stiffness and stability of the degree of clinical lumbar spine for the surgical treatment of injuries pilot basis and to provide theoretical basis.To assess the biomechanical stability of the lumbar intervertebral segmental stiffness among posterior lumbar interbody fusion one anatomical posterolateral cage per functional spinal unit with unilateral or bilateral transpedicular screw rod fixation.The second part of article ,to explore the clinical feasibility and efficiency of treatment of lumbar disc protrution with unilateral vertebral plate decompression, interbody fusion and pedicle screw fixation.Methods:In the biomechanical experiment, 20 corpse lumbar functional spinal units(FSU) were randomly divided in 2 groups.One group was L4/5FSU;another group was L4/5,L5/S1FSU.The number of lumbar FSU in each group was 10. Each lumbar sample was made into 3 kind of models by turns: (1) Normal lumbar unit model; (2)Right unilateral facetectomy and discoidectomy,and then one single cage per FSU was implanted into intervertebral disc with PLIF method,and it was fixed by right unilateral transpedicular screws; (3)Bilateral facetectomy and disco ibdectomy,and then one single cage per FSU was implanted into intervertebral disc with PLIF method,and it was fixed by bilateral transpedicular screws. These lumbar samples were all performed by WDW-4100 experimental machine under 6 different undestructive tests in flexion,extension,right or light bending and right or light torsion.In the clinical survey,from February 2006 to February 2008,24 patients underwent posterior lumbar interbody fusion(PLIF). The following data were recorded within 1-year average follow-up: surgical time, estimated blood loss, duration of hospital stay,satisfactory clinical outcome in short-term and medium- term.Results:In the biomechanical experiment, (1)The stiffness and ROM of One Spinal Unit(OSU)L4/5 : Under flexion,extension,right or light bending and right or light torsion, Uni-Fixational Fusion(UFF) models were not statistical significance with Di-Fixational Fusion(DFF) models. (2) The stiffness and ROM of Two Spinal Units (TSU)-L4/5 and L5/S1:Under flexion,light bending and right or light torsion, UFF models were not statistical significance with DFF models. The stiffness and ROM of TSU:Under extension and right bending, UFF models were statistical significance with DFF models. In the clinical survey,all patients were followed up 3-24 months (average 12 months),who resenting with preoperative low back pain and/or lower extremity radicular pain (n=24) had resolution of symptoms postoperative. The last follow- up's Oswestry Disability Index(ODI) P0-P5 respectively was 5,11,6,2,0,0.The clinical outcomes were determined using a JOA criteria,which revealed that 18 patients had excellent result,4 had good,2 had fair. The fineness rate was 91.67%。Conclusion:In the biomechanical experiment:(1)For the seriously OSU and unilateral lunbar degenerative diseases and lumbar instability, the biomechanical effect of unilateral transpedicular screws fixation plus anatomi cal threaded cage and interbody fusion is fineness,and stiffness is well,which offers the lunbar instantly stability. (2)For the seriously TSU'degenerative diseases,we should rigourly control the operational indication;plusing anatomical threaded cages and interbody fusion,we do stress the importment of scientifically exercising the psoas when patients lying in bed,which in order to improve the lunbar stability in the long-term. In the clinical survey,the unilateral fixation could be used in patients with lumbar disc herniations who need lumbar spinal fusion.