Use of S2-alar-iliac screws for lumbopelvic fixation and reconstruction in the treatment of lumbosacral spinal tuberculosis

English Keywords:Spinal tuberculosis  Lumbosacral region  S2-alar-iliac screw  Surgical treatment  Internal fixation

English Abstract:

  【Abstract】 Objectives: To investigate the feasibility and safety of free-hand technique of S2-alar-iliac (S2AI) screw placement in the lumbopelvic fixation, and to evaluate the clinic values in the treatment of lumbosacral spinal tuberculosis. Methods: Retrospective analysis the lumbosacral spinal tuberculosis patients who had underwent pelvic fixation using S2AI technique from October 2014 to October 2016. Total of 16 cases were enrolled in this study, consist of 9 females and 7 males, with an average age of 63.5±14.3 years. Of those patients, 11 were older than 60 years, as well as 10 patients had severe osteoporosis based on preoperative bone mineral density examination(T＜-3.5). S2AI screws were used for lumbopelvic reconstruction. Postoperative X-ray and CT scan were used to evaluate the optimal trajectory and direction of S2AI screws. Screw related complications as well as healing process of tuberculosis were recorded. Results: Ten patients underwent posterior only fixation and intervertebral debridement, while six patients received one-stage posterior fixation combined with anterior debridement and fusion. Thirty S2AI screws were inserted by free-hand technique. All trajectories were confirmed by postoperative X-ray and CT scan. The average abduction angle in coronal plan(α angle) was 65°±14°(range, 50°-80°), the average caudal angle related to S1 endplate in sagittal plan(β angle) was 0°±12°(range, -15°-16°), the average angle related to central line in axial plan(θ angle) was 50°±9°(range, 45°-57°). One screw(3.3%) protruded iliac inner cortex, two(6.7%) protruded iliac external cortex. All the protrusions were less than 5mm, without any visceral or neurovascular structures and none required removal or revision. The average follow-up was 12 months. One patient with sever osteoporosis was observed periscrew halo lucency bilaterally(6.7%). ESR and CRP decreased to normal at 6 months of follow-up. All those patients were asymptomatic at last follow-up and returned to normal life without the evidence of instrumentation failure, and solid fusion was confirmed by X-ray in all patients. The average of VAS score on back pain improved significantly from 7.7±2.1 preoperatively to 3.2±0.7 postoperatively(P=0.03). Conclusions: The free-hand technique of S2AI screw placement appears to be a safe and acceptable method of insertion, without major complications. S2AI screw provides rigid lumbosacral fixation and gives conditions for the cure of spinal tuberculosis.