| Objective: The goals were to compare the outcomes,value and surgical skill of using posteolateral fusion versus posterior lumbar interbody fusion in the treatment of degenerative spondylolisthesis.Methods: This retrospective study analyzed the outcome of 44 patients with single level degenerative spondylolisthesis during the period from April 2000 to October 2004. All the patients were divide random tow groups: I (PLIF) Treatment group consisted of 23 patients who had underwent laminectomy ,decompression of spinal canal and posterior lumbar interbody fusion with single oblique cage supplemented pedicle screw-rod fixation 9 males and 14 females with average age at time of operation of 51.4 years (range 45–68 years);the course of disease was average 2.6 years (range 0.5–6 years); Grade I 13 and Grade II 10 according to the classification by Meyerding ; 16 L4–5 segment slippage, 7 L5-S1 segment slippage.20 patients had preoperative back pain was present in, 15 patients had neurogenic claudication, and 17 patients had radicular leg pain.Motor weakness in the nerveroot distributio was present in 16 patients, sensory deficit in 11 patients ,tendinous reflex weakness in 9 patients. II (PLF) Control group consisted of 21 patients who had underwent laminectomy,decompression of spinal canal and Posterolateral lumbar Fusion supplemented pedicle screw-rod fixation.8 males and 13 females with average age at time of operation of 53.4 years (range 46–70 years);the course of disease was average 3.1years (range 0.6–7 years); Grade I 12 and Grade II 9 ;15 L4–L5 segment slippage ,6 L5-S1 segment slippage.18 patients had preoperative back pain was present in, 12 patients had neurogenic claudication, and 15 patients had radicular leg pain.Motor weakness in the nerveroot distribution was present in 13 patients, sensory deficit in 9 patients ,tendinous reflex weakness in 10 patients, Bladder or bowel symptoms in 1 patients. Surgical Technique: The edidural anesthesia was applied in all of the patients.A posterior longitudinal incision in middleline including slippage provided direct access to expose the spinous processes,lamina, transverse process and facet joints.Making sure the position of slippage segment and then cut off a bit superior articular process in order to expose point which pedicle screw were to placed. An acknowledged criterion of"AO"was used to placed pedicle screw: the point was at the intersection of a linedrawn transversely through the midportion of the transverse process and linedrawn vertically through outbord hem of the facet joints. Short segment pedicle fixation including slippage segment and adjacent inferior segment were conducted to all the patients.It's proved perfect position by X-ray then began to relieve of pressure of vertebral canal. The PLIF used approach that involved laminectomy,entire inferior of slippage segment and 1/3～2/3 adjacent inferior segment superior articular process facetectomy,foraminotomy. nerve roots were retracted and bilateral incisions were made over the disc.when verified that its were protected. The disc nucleus was exscinded entirely.Applying instruments to support the interbody space and reduce the slippage segment. In the PLF group,the preceding procedure was samely performed .At the same time disc nucleus would be exscinded if was there protrusion of the lumbar intervertebral disc.After adequate decompression and reducation, the bed for graft was prepared. In the PLIF group: the disc nucleus was exscinded entirely, end plates were curetted to the bleeding cancellous bone. Autologous iliac crest cancellous bone was inserted cage, which then single proper cage were placed in the disc spaces at an angle of 45o anteriorposteriorly and then closed suction drainage system was employed. In the PLF group, Subperiosteal dissection was performed between the transverse processes and lateral aspects of the facet joints. Iliac crest autograft was placed in this bed after stabilization with pedicle screws and Isola rods.The Clinical outcome according to relief of pain was assessed using the scoring system of the Japanese Orthopaedic Association (JOA) for low back pain and the scoring system of Visual analogue scale. In radiographic assessment: Preoperative and 1 week ,3 month and last follow-up radiographs were analyzed including the index of Taillard ,relative posterior disc height and fusion rate.All datas between the two groups were calculated by using SAS6.12 statistical software.Results: The mean follow-up period for this study was 28.5 months (range 15–36 months).In PLIF group: The JOA scores before surgery averaged 14.52±4.83 points and after surgery increased to 24.69±3.53(paired ttest, p< 0.01),which resulted in an 81% satisfactory outcome (excellent and better) according to the rate of the improved JOA score (RIS);the VAS score of the low back pain and radicular leg pain before surgery averaged 7.36±0.62 and 6.21±0.54 decreased to1.89±0.55and 0.61±0.33 (P<0.01)respectively. In PLF group: The JOA scores before surgery averaged 15.23±4.27 points and after surgery increased to 23.48±4.26(p< 0.01),which resulted in an 76% satisfactory outcome;the VAS score of the low back pain and radicular leg pain before surgery averaged 7.66±0.47 and 6.85±0.28 decreased to 2.3±0.47 and 0.73±0.34(P<0.01)respectively.After operation,the difference between the two groups was not statistically significant in JOA score and RIS (P>0.05).However, the difference was statistically significant in the VAS score of the low back pain between the two groups(P<0.05). Radiographic assessment,In PLIF group: relative disc height before surgery averaged 54.2±9.9% and after surgery increased to 84.9±9.7%, at last follow-up it's 82.5±9.2%; the index of Taillard was 24.3±7.1% before surgey and 5.81±4.9 after operation, at last follow-up 6.6±0.96%,In PLF group: relative disc height before surgery averaged 52.2±9.5% and after surgery increased to 83.7±5.9%, at last follow-up it's 75.0±7.1%; the index of Taillard was 23.4±6.2% before surgey and 6.4±4.7% after operation, at last follow-up 7.7±1.1%.The difference was statistically significant in relative disc height and the index of Taillard between the two groups at last follow-up (P<0.05).There were one nonunions in the PLIF group and three in the PLF, the fusion rate was 95.7% vs 85.7%, it showed no statistical difference in two group (p>0.05).Compliciations: there were 2 dural tears and 1 disc space infection and 4 transient neuropraxia in PLIF.There were 3 pseudarthrosis which caused low back pain and 1 instrumentation failure in PLF.Conclusion: This study demonstrated : adequate decompression and solid fusion was a satisfactory procedure for treating degenerative lumbar spondylolisthesis.Comparing with PLF procedure,PLIF showed better outcomes in maintaining disc height and restoration of sagittal balance.On the other hand, PLIF was a high rate of fusion,lower of implant failure and improved low back pain because of predominant biomechanics. It's an ideal method for posterior lumber interbody fusion in the treatment of degenerative spondylolisthesis...
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