title: Minimally invasive unilateral versus bilateral technique in performing single-segment pedicle screw fixation and lumbar interbody fusion.
abstract: OBJECTIVE
  The minimally invasive transforaminal lumbar interbody fusion procedure with percutaneous pedicle screws was adopted in clinical practice, but the choice between a unilateral pedicle screw (UPS) or bilateral pedicle screw (BPS) fixation after lumbar fusion remains controversial. The purpose of the present retrospective study was to compare the clinical outcomes and radiological results of unilateral and bilateral pedicle screw fixations.
  
  
  METHODS
  The retrospective study recruited seventy-eight patients with a single-level pedicle screw fixation and lumbar interbody fusion at L4-L5 or L5-S1 from January 2010 to January 2013. The patients were treated with MIS TLIF with BPS fixation, and since May 2012, all patients were treated with UPS fixation. The perioperative outcomes including operative time, blood loss, hospital-stay length, and complication rates were accessed. Radiological outcomes regarding fusion were determined with the Bridwell grading system. Clinical outcomes were evaluated with the Oswestry Disability Index (ODI) and visual analog scale (VAS) during the mean follow-up of 2 years.
  
  
  RESULTS
  According to perioperative assessments, the operative time was significantly shorter for group UPS (84.7 ± 6.4 min) than for group BPS (103.6 ± 10.6 min; p < 0.0001), and similar results were found with regard to the mean blood loss (UPS, 96.3 ± 17.5; BPS, 137.4 ± 32.9, p < 0.0001). With regard to the hospital-stay period, though the UPS group seems shorter, there is no statistical significance (UPS, 10.0 ± 2.1; BPS, 10.4 ± 2.4, p = 0.428). There were four in the BPS group and six in the UPS group defined as unfused at 6 months pest-operative, but at 12 months post-surgery, all patients achieved solid fusion. Regarding clinical outcomes, the VAS and ODI scores were significantly lower in the UPS group than the BPS group at 7 days post-surgery, but there was no difference at 1 month post-surgery and during the later follow-up.
  
  
  CONCLUSIONS
  There was no difference between the UPS and BPS flexion techniques about the clinical outcomes at 24 months post-surgery. However, because the UPS involves a shorter surgical time, less blood loss, faster pain relief, and faster functional recovery, UPS might be more suitable in performing single-segment pedicle screw fixation and lumbar interbody fusion.
authors.affiliation: Department of Orthopaedics, The General Hospital of Jinan Military, No.25 Shifan Road, Tianqiao Square, Jinan, 250031, China. cc_jno@163.com.
authors.forename: Chen
authors.initials: C
authors.lastname: Chen
authors.affiliation: Department of Orthopaedics, The General Hospital of Jinan Military, No.25 Shifan Road, Tianqiao Square, Jinan, 250031, China. xccao_jno@163.com.
authors.forename: Xuecheng
authors.initials: X
authors.lastname: Cao
authors.affiliation: Department of Orthopaedics, The General Hospital of Jinan Military, No.25 Shifan Road, Tianqiao Square, Jinan, 250031, China. med@163.com.
authors.forename: Lin
authors.initials: L
authors.lastname: Zou
authors.affiliation: Department of Orthopaedics, The General Hospital of Jinan Military, No.25 Shifan Road, Tianqiao Square, Jinan, 250031, China. hgl_ddr@163.com.
authors.forename: Guangliang
authors.initials: G
authors.lastname: Hao
authors.affiliation: Department of Orthopaedics, The General Hospital of Jinan Military, No.25 Shifan Road, Tianqiao Square, Jinan, 250031, China. zyz_ortho@163.com.
authors.forename: Zhenyu
authors.initials: Z
authors.lastname: Zhou
authors.affiliation: Department of Orthopaedics, The General Hospital of Jinan Military, No.25 Shifan Road, Tianqiao Square, Jinan, 250031, China. guichun_zzz@163.com.
authors.forename: Guichun
authors.initials: G
authors.lastname: Zhang
mesh_terms: D000368:Aged; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D055959:Intervertebral Disc Degeneration / Q000000981:diagnostic imaging / Q000601:surgery; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging* / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D019060:Minimally Invasive Surgical Procedures / Q000379:methods*; D065289:Pedicle Screws / Q000706:statistics & numerical data; D011859:Radiography; D020127:Recovery of Function / Q000502:physiology; D012189:Retrospective Studies; D013123:Spinal Fusion / Q000379:methods*