Comparison Of Unilateral Versus Bilateral Posterior Lumbar Fixation In Two-level Degenerative Diseases Of The Lumbar Spine

Objective: To investigate the clinical efficacy and imaging results of unilateral and bilateral posterior lumbar fixation in the treatment of bilateral degenerative diseases.Methods: From March 2015 to May 2019,63 patients with two-level degenerative diseases of the lumbar spine who were treated by lumbar posterior unilateral pedicle screw fixation(UPSF)and bilateral pedicle screw fixation(BPSF)were retrospectively analyzed.A total of 31 patients in the UPSF group,16 had intervertebral fusion,9 had posterolateral fusion,and 7had intervertebral fusion combined with posterolateral fusion.In the BPSF group,all 32 cases underwent intervertebral fusion.The improved Visual analog scale(VAS)scores and Oswestry Disability Index(ODI)were used to evaluate the postoperative clinical efficacy,and the intervertebral disc height changes of operative segmental and cranial adjacent segmental,as well as the changes of lumbar lordosis were compared according to the imaging data,and fusion grades were evaluated by the Bridwell grading.Results: The mean follow-up period in all patients was 34.3±12.7months,and there was no significant difference in age,gender,body mass index(BMI),follow-up period,preoperative diagnosis and operated segments between the two groups.Obviously,the UPSF group was significantly lower than the BPSF group in terms of operation time,intraoperative blood loss and hospitalization expenses(P<0.001).VAS back and leg pain scores and ODI scores were significantly reduced in both groups after surgery at each time points and before surgery(P<0.001).The intervertebral disc height and lumbar lordosis(LL)in both groups after surgery at each time points was significantly increased compared with that before surgery(P<0.001).At the last follow-up,the disc height of cranial adjacent segmental between the two groups was reduced significantly in the UPSF group than in the BPSF group(P<0.001).There was no statistically significant difference in the rate of postoperative interbody fusion between the two groups(P>0.05).In the UPSF group,screw loosening occurred in 15 patients during the final follow-up after surgery,including 2 patients in the cranial side,10 patients in the caudal side,and 3 patients in both the cranial and caudal sides.In the BPSF group,there were 3 patients,all of which occurred caudal side.However,the intermediate vertebral screw was not loosened in all patients.The incidence of screw loosening in the unilateral fixation group was significantly higher than that in the bilateral fixation group(P<0.001).Conclusions: Unilateral fixation and bilateral fixation have similar clinical effects in the treatment of two-level degenerative diseases of the lumbar spine,and reduce the muscle injury,operation time,intraoperative blood loss,hospitalization expenses and delay the adjacent segment degeneration(ASD).Although the caudal screws were loosened in some patients,there was no significant difference on the clinical efficacy.