title: High-grade spondylolisthesis treated using a modified Bohlman technique: results among multiple surgeons.
abstract: OBJECTIVE
  The ideal surgical management of high-grade spondylolisthesis remains unclear. Concerns regarding the original Bohlman transsacral interbody fusion technique with stand-alone autologous fibular strut include late graft fracture and incomplete reduction of lumbosacral kyphosis. The authors' goal was to evaluate the radiographic and surgical outcomes of patients treated for high-grade spondylolisthesis with either transsacral S-1 screws or standard pedicle screw fixation augmenting the Bohlman posterior transsacral interbody fusion technique.
  
  
  METHODS
  A retrospective review of patients who underwent fusion for high-grade spondylolisthesis in which a Bohlman oblique posterior interbody fusion augmented with either transsacral or standard pedicle screw fixation was performed by 4 spine surgeons was completed. Estimated blood loss, operating time, perioperative complications, and need for revision surgery were evaluated. Upright pre- and postsurgical lumbar spine radiographs were compared for slip percent and slip angle.
  
  
  RESULTS
  Sixteen patients (12 female and 4 male) with an average age of 29 years (range 9-66 years) were evaluated. The average clinical follow-up was 78 months (range 5-137 months) and the average radiographic follow-up was 48 months (range 5-108 months). Ten L4-S1 and 6 L5-S1 fusions were performed. Five fibular struts and 11 titanium mesh cages were used for interbody fusion. Six patients had isolated transsacral screws placed, with 2 (33%) of the 6 requiring revision surgery for nonunion. No nonunions were observed in patients undergoing spanning pedicle screw fixation augmenting the interbody graft. Six patients experienced perioperative complications including 3 iliac crest site infections, 1 L-5 radiculopathy without motor involvement, 1 deep vein thrombosis, and 1 epidural hematoma requiring irrigation and debridement. The average estimated blood loss and operating times were 763 ml and 360 minutes, respectively. Slip percent improved from an average of 62% to 37% (n = 16; p < 0.01) and slip angle improved from an average of 18° to 8° (n = 16; p < 0.01). No patient experienced L-5 or other motor deficit postoperatively.
  
  
  CONCLUSIONS
  The modified Bohlman technique for treatment of high-grade spondylolisthesis has reproducible outcomes among multiple surgeons and results in significant improvements in slip percent and slip angle. Fusion rates were high (14 of 16; 88%), especially with spanning instrumentation augmenting the oblique interbody fusion. Rates of L-5 motor deficit were low in comparison with techniques involving reduction of the anterolisthesis.
authors.affiliation: Orthopaedic Surgery, Oregon Health & Science University, Portland;
authors.forename: Robert A
authors.initials: RA
authors.lastname: Hart
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Domes
authors.forename: Brady
authors.initials: B
authors.lastname: Goodwin
authors.forename: Charles R
authors.initials: CR
authors.lastname: D'Amato
authors.forename: Jung U
authors.initials: JU
authors.lastname: Yoo
authors.forename: Ronald J
authors.initials: RJ
authors.lastname: Turker
authors.forename: Matthew F
authors.initials: MF
authors.lastname: Halsey
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D016063:Blood Loss, Surgical / Q000706:statistics & numerical data; D002648:Child; D005260:Female; D006801:Humans; D016268:Internal Fixators; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D061646:Operative Time; D011183:Postoperative Complications / Q000453:epidemiology; D010818:Practice Patterns, Physicians' / Q000706:statistics & numerical data; D011859:Radiography; D012086:Reoperation; D012189:Retrospective Studies; D013123:Spinal Fusion / Q000295:instrumentation / Q000379:methods*; D013168:Spondylolisthesis / Q000000981:diagnostic imaging / Q000601:surgery*; D016896:Treatment Outcome