531 - Interspinous Process Fixation versus Pedicle Screw Fixation in Circumf...

General Session: MIS-3

Presented by: P. Passias - View Audio/Video Presentation (Members Only)


K. Kim(1), R. DenHaese(2), C. Hill(3), B. Strenge(3), A. de Moura(4), A. Kranenburg(5), M. Dennis(6), A. Cappuccino(7), T. Thaiyananthan(8), P. Arnold(9), P. Passias(4), B. Bejin(10), C. Moore(11), S. Martineck(12), C. Ferry(10), K. Martin(10)

(1) UC Davis Health System, Sacramento, CA, United States
(2) AXIS Neurosurgery and Spine, Williamsville, NY, United States
(3) Orthopaedic Institute, Paducah, KY, United States
(4) New York Spine Institute, New York, NY, United States
(5) Southern Oregon Orthopedics, Medford, OR, United States
(6) South Texas Spinal Clinic, San Antonio, TX, United States
(7) Buffalo Spine Surgery, Buffalo, NY, United States
(8) Brain and Spine Institute of California, Newport Beach, CA, United States
(9) University of Kansas Hospital, Kansas City, KS, United States
(10) Zimmer Biomet Spine, Broomfield, CO, United States
(11) University of Colorado Denver, Denver, CO, United States
(12) Medical Device Clinical Trial Consultant, Buffalo, NY, United States


Introduction: Spinal arthrodesis with supplemental posterior fixation is an effective surgical intervention for patients presenting with pain secondary to degenerative spine. Circumferential constructs provide the stability of a large interbody cage, while also enhanceing sagittal balance and segmental rigidity via the posterior fixation. However, given the structurally robust nature of an anterior (ALIF) or lateral (LLIF) cage, extensive invasive posterior instrumentation is often unnecessary. Accordingly, rigid interspinous process fixation (ISPF), placed through a minimally disruptive mid-line incision, has been proposed as a less invasive alternative to traditional pedicle screw fixation (PSF). Level I comparative evidence regarding ISPF is still limited, however. Hence, further characterization of the ISPF technology in the circumferential fusion model is needed to establish its efficacy. Aims and

Objectives: The aim of this analysis was to prospectively compare the outcomes of subjects receiving circumferential lumbar arthrodesis with adjunctive ISPF or PSF.

Methods: Data was collected as part of a prospective randomized controlled multi-center (11 investigators) study of 103 subjects receiving single-level lumbar interbody fusion (IBF) with supplemental ISPF (n=66) or PSF (n=37) for the treatment of degenerative disc disease +/- spondylolisthesis (low grade). The target randomization ratio was 2:1, ISPF (Aspen MIS Fusion System, Zimmer Biomet Spine) to PSF subjects. The PSF approach (MIS or Open; Unilateral or Bilateral) and interbody access approach (lateral or anterior) were performed per investigator institutional stand-of-care. Perioperative and patient-reported follow-up outcomes at 1.5, 3, 6, and 12months were collected and stratified by posterior fixation type. Comparative analysis was performed using a linear mixed model which included a random intercept accounting for within-site correction.

Results: See Table 1 and Figure 1 for patient demographics and follow-up outcomes. Age, sex, and BMI were not significantly associated with any study metric.

Conclusions: At 1-year, multiple follow-up metrics indicate that ISPF is a clinically effective adjunct to circumferential arthrodesis and performs well in comparison to PSF. Further assessment of outcomes at 2 years is necessary to characterize outcome maintenance and longevity.

Table 1: Patient Demographics and Follow-Up Outcomes

Figure 1: ODI Change vs. Time