title: Open versus minimally invasive sacroiliac joint fusion: a multi-center comparison of perioperative measures and clinical outcomes.
abstract: BACKGROUND
  Sacroiliac (SI) joint pain is an under diagnosed source of low back pain due in part to lack of visible pathology on radiographs and symptoms mimicking other back-related disorders. Open SI joint fusion has been performed since the 1920s. This technique has fallen out of favor with the introduction of minimally invasive options. To date there has been no direct comparison between open and MIS SI joint fusion.
  
  
  METHODS
  We conducted a multi-center, retrospective comparative cohort study of patients who underwent SI joint fusion using either an open surgical (OS) technique using a combination of screws and cages or a minimally invasive surgical (MIS) technique with a series of titanium plasma spray (TPS) coated triangular implants. Operative measures including surgical operating time, length of hospitalization and estimated blood loss (EBL) were collected along with demographics and medical history, surgical complications, and 12- and 24-month pain scores. Improvements in pain were compared after matching for age and gender and controlling for a history of lumbar spine fusion using repeated measures analysis of variance.
  
  
  RESULTS
  Data were available for 263 patients treated by 7 surgeons; 149 patients treated with OS and 114 treated with MIS SI joint fusion. Compared to OS patients, MIS patients were on average 10 years older (mean age 57 vs. 46) and 69% of all patients were female. MIS operative measures of EBL, operating time and length of hospitalization were significantly lower than open surgery (p < 0.001). Pain relief, measured as change from baseline to 12 months in VAS pain rating, was 3.5 points lower in the MIS vs. OS group (-6.2 vs. -2.7 points, p < 0.001). When matched for age, gender and a history of prior lumbar spinal fusion, postoperative pain scores were on average 3.0 points (95% CI 2.1 - 4.0) lower in MIS vs. OS (rANOVA p < 0.001).
  
  
  CONCLUSIONS
  In this multi-center comparative study, patients who underwent either OS or MIS SI joint fusion showed postoperative improvements in pain score. Compared to OS patients, patients who underwent MIS SI joint fusion had significantly greater pain relief and more favorable perioperative surgical measures.
authors.forename: Arnold Graham
authors.initials: AG
authors.lastname: Smith
authors.affiliation: SI-BONE, Inc,, 3055 Olin Ave, Suite 2200, San Jose, CA, USA. rcapobianco@si-bone.com.
authors.forename: Robyn
authors.initials: R
authors.lastname: Capobianco
authors.forename: Daniel
authors.initials: D
authors.lastname: Cher
authors.forename: Leonard
authors.initials: L
authors.lastname: Rudolf
authors.forename: Donald
authors.initials: D
authors.lastname: Sachs
authors.forename: Mukund
authors.initials: M
authors.lastname: Gundanna
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Kleiner
authors.forename: Milan G
authors.initials: MG
authors.lastname: Mody
authors.forename: A Nick
authors.initials: AN
authors.lastname: Shamie