| Background Lumbar spondylolisthesis is one of the common causes of lumbocrural pain,which seriously affects the quality of daily life for the patients and often requires surgical treatment.Due to the advantages of the ability to provide 3-column fixation,to facilitate short-segment instrumentation,and to maintain anatomic or desired sagittal alignment,the Posterior lumbar interbody fusion(PLIF)method has currently been regarded as the classic surgical procedure for lumbar spondylolisthesis.The key to the fixation is the strength obtained by the screws in the trabecular bone of the pedicle and vertebral body(VB).However,for the patients with osteoporosis(OP),there is usually a high risk of screw loosening and detachment,due to the decreasing bone density of the vertebral body,the thinning trabecular bone,and the significant reduction of the holding force of the screw-bone interface.Studies showed that the screw loosening rate is as high as 11%~21.2% after five years’ follow-up of lumbar PLIF surgery performed in the OP patients.At present,in order to improve the stability of the pedicle screws in osteoporotic vertebral body and reduce the rate of screw loosening,spine surgeons have to choose to increase the fusion levels that sacrificing the lumbar range of motion;or inject bone cement into the screw canal,that facing the possibility of serious bone cement leakage related complications such as vascular-nerve injury and pulmonary cement embolism.Based on these clinical requirements,our research group had developed a new type of FPS with a “gradient hole” structure.Previous experiments revealed that the FPS had superior in terms of strength of screw fixation and low cement leakage rate,and it was applied in clinical practice in 2013.The purpose of this study is to analyze the results of lumbar fusions in spondylolisthesis patients with poor bone quality performed with the new FPS comparing with the common pedicle screw(CPS),to verify the clinical efficacy and safety of this novel fixation instrument.Purpose: This study evaluates the safety and efficiency of a new-structured Polymethylmethacrylat(PMMA)-augmented fenestrated pedicle screw(FPS)in the treatment of lumbar spondylolisthesis with osteoporosis(OP).Material and Methods: The authors retrospectively reviewed 66 patients suffering from the lumbar spondylolisthesis and OP.FPSs were instrumented in 32 patients,that included in the FPS group,and enrolled the other 34 patients who were implanted with common pedicle screw(CPS)in the CPS group.Record the duration of surgery,the amount of intraoperative blood loss and the length of hospital stay.Measure the radiological data and take the Oswestry Disability Index Questionnaire(ODI)score and Visual Analogue Score(VAS)scores at pre-operation,post-operation and the last follow-up.Results: After 12-65 months follow-up(mean 41.8 months): 1.Comparison of the surgical data: although the operation of FPS group was more complicated,there was no statistically significant difference of time consuming of operation,intraoperative blood loss and hospitalization between the two groups(p=0.264,p=0.658,p=0.856).2.Comparison of the radiological data: the FPS group exhibited significantly higher reduction rate of slippage(85.6 vs.66.8% for CPS,p=0.001),rate of kyphosis deformation correction(80.0 vs.50% for CPS,p=0.034),and fusion rate(100.0 vs.82.4% for CPS,p=0.025)and greater improvement of the ODI score(81.1 vs.64.4% for CPS,p=0.001)and the VAS score(84.7vs.72.7% for CPS,p=0.004);3 FPSs in this study(rate 2.2%)occurred intraoperative cement leakage,all of which were Yeom type-C;however,there was no postoperation discomfort.3.Evaluation of pain and function: The ODI score and VAS score of the two groups were significantly improved(p<0.05)at 3 months and 12 months after surgery,and at the last follow-up,the ODI score of the FPS group was 81.1%,which was much higher than 64.4% of the CPS group(p=0.001).The VAS score of the FPS group was 53.8 mm lower than that before surgery at the last follow-up,which of CPS group is 44.1 mm,and the FPS group was significantly better than the CPS group(p=0.004).4.Complications: During the follow-up period,all cases of the FPS group had no recurrence,no screw loosening and fragmentation and according to the Suk standard,the success rate of intervertebral fusion was 100%.But in the CPS group,there were 2 cases of pedicle screw fracture(4 CPS,nail break rate 5.9%),2 cases of pedicle screw loosening(5.9% loosening rate,2 patients had different degrees of spondylolisthesis),and on account of 30 cases success fusion,the fusion success rate was 88.2%.Excluding bone cement leakage,the incidence of complications of the CPS group(17.7%)was significantly higher than the FPS(0%,p=0.025).However,there was no statistically significant difference in the overall complication rate between the two groups(9.4% in the FPS group,p=0.477)and fusion success rate(p=0.113).Conclusions: The new-structured FPS offered greater slippage reduction ability,deformity correction,and fusion rate compared with the CPS in the treatment of lumbar spondylolisthesis with OP.Moreover,it resulted in no severe PMMA-related complication and no pedicle screw fracture that provided a safe option for those patients. |
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