[Free-hand technique of S(2) alar iliac screw placement for sacropelvic fusion in lumbar degenerative scoliosis].

ABSTRACT

Objective: To evaluate the feasibility of placement of S(2) alar iliac screw (S(2)AI) using free-hand technique for sacrapelvic fusion in lumbar degenerative scoliosis. Methods: Eighteen patients with Lumbar Degenerative Scoliosis treated by S(2)AI screw fixation at Department of Orthopedics, General Hospital of Southern Theater Command of People's Liberation Army and Department of Orthopedics, 89th hospital of People's Liberation Army from August 2014 to October 2018 were analyzed retrospectively. There were 5 males and 13 females, aged 63.2 years old (range55 to 71 years old).Parameters of spine including Cobb Angle, C(7) plumb line -center sacral vertical line (C(7)PL-CSVL), lumbar lordosis(LL), sagittal vertical axis(SVA), pelvic incidence(PI), pelvic tilt(PT), sacral slope (SS) and pI-LL were measured on the whole spine X-ray before operation and at final follow-up. Pelvic CT scan was performed postoperatively to assess the accuracy of S(2)AI placement. Oswestry disability Index (ODI) was also recorded. The data were compared by paired t test or Wilcoxon tests. Results: All patients were followed up for 23.7 months (range 12~62 months).At the last follow up, Cobb Angle decreased from (32.28±4.97) °preoperative to (6.56±3.20) ° (t=41.142, P<0.01) and C(7)PL-CSVL deceased from (1.11±2.07) cm preoperative to (0.18±1.08) cm (t=41.142, P=0.06) .LL improved from (-22.39±13.07) °preoperative to (-36.39±4.29) ° (t=4.470, P<0.01) , PI-LL decreased from (26.83±14.83)°preoperative to (13.72±8.3)° (t=4.396, P<0.01) , PT decreased from (27.94±4.26) °to (23.39±6.08) ° (t=2.680, P=0.02) , and SS increased from (22.22±6.36) °to (26.28±7.24) ° (t=-2.178, P=0.04) .SVA decreased from (6.54±4.51) cm preoperative to (2.62±1.29) cm (t=3.052, P=0.01) .ODI decreased from 0.58(0.40) (M(Q(R))) to 0.18 (0.15) (Z=-4.567, P<0.01) .No complications such as nerve and blood vessel injury occurred during the operation. A total of 32 S(2)AI screws were placed, 3 screws were placed with mild to moderate cortical breaches, 2 were perforated the pelvis ventrally, 1 was perforated posteriorly, with no clinically notable neurovascular or visceral complications. Eight patients finished the SRS-22 questionnaire, with mean score of 4.4 in terms of satisfaction with management. Conclusions: Free-hand technique of S(2)AI screw placement for sacrapelvic fusion in degenerative lumbar scoliosis is safe and feasible.S(2)AI fixation in DLS can provide great correction of deformity, maintain the stability of lumbo-pelvic area and improve the clinical symptoms.