Rates of Loosening, Failure, and Revision of Iliac Fixation in Adult Deformity Surgery.


Study design

Retrospective cohort review of a prospective multicenter database.


Identify rates and variations in lumbopelvic fixation failure after adult spinal deformity (ASD) correction.

Summary of background data

Traditional iliac (IS) and S2-alar-iliac (S2AI) pelvic fixation methods have unique technical characteristics for their application, and result in varied bio-mechanical and anatomic impact. These differences may lead to variance in lumbopelvic fixation failure types/rates.


ASD patients undergoing correction with more than five level fusion and pelvic fixation, separated by pelvic fixation type (IS vs. S2AI). Fixation fracture or loosening assessed radiographically (Figure 1). Multivariate logistic regression, accounting for significant confounders, was used to examine differences between the two groups for screw loosening/fracture, rod fracture, and revision surgery. Level of significance set at P< 0.05.


Four hundred eighteen of 1422 patients were included (IS = 287, S2AI = 131). The groups had similar age, body mass index (BMI), baseline comorbidities, number of levels fused (P>0.05), baseline health related quality of life measures (HRQLs) (short form survey-36, Oswestry Disability Index [ODI], Scoliosis Research Society [SRS-22], numeric rating scale [NRS] leg and back, P>0.05) and deformity (pelvic tilt [PT], pelvic incidence-lumbar lordosis [PI-LL], and sagittal vertical axis [SVA], P> 0.05). The IS group had more unilateral fixation versus S2AI (12.9% vs. 6%; P = 0.02). The overall lumbopelvic fixation failure rate was 23.74%. Pelvic fixation (13.4%) and S1 screw (2.9%) loosening was more likely with S2AI (odds ratio [OR] 2.63, P = 0.001; OR 6.05, P = 0.022). Pelvic screw (2.3%) and rod fracture (14.1%) rates similar between groups but trended toward less occurrence with S2AI (OR 0.47, P= 0.06). Revision surgery occurred in 22.7%, and in 8.5% for iliac fixation specifically, but with no differences between fixation types (P = 0.55 and P = 0.365). Pelvic fixation failure conferred worse HRQL scores (physical component score [PCS] 36.23 vs. 39.37, P= 0.04; ODI 33.81 vs. 27.93, P = 0.036), and less 2 years improvement (PCS 7.69 vs. 10.46, P = 0.028; SRS 0.83 vs. 1.03, P = 0.019; ODI 12.91 vs. 19.77, P = 0.0016).


Lumbopelvic fixation failure rates were high following ASD correction, and associated with lesser clinical improvements. S2AI screws were more likely to demonstrate loosening, but less commonly associated with rod fractures at the lumbopelvic region.





Published Version (Please cite this version)


Publication Info

Eastlack, Robert K, Alex Soroceanu, Gregory M Mundis, Alan H Daniels, Justin S Smith, Breton Line, Peter Passias, Pierce D Nunley, et al. (2022). Rates of Loosening, Failure, and Revision of Iliac Fixation in Adult Deformity Surgery. Spine, 47(14). pp. 986–994. 10.1097/brs.0000000000004356 Retrieved from https://hdl.handle.net/10161/28004.

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Peter Passias

Instructor in the Department of Orthopaedic Surgery

Khoi Duc Than

Professor of Neurosurgery

I chose to pursue neurosurgery as a career because of my fascination with the human nervous system. In medical school, I developed a keen interest in the diseases that afflict the brain and spine and gravitated towards the only field where I could help treat these diseases with my own hands. I focus on disorders of the spine where my first goal is to help patients avoid surgery if at all possible. If surgery is needed, I treat patients using the most advanced minimally invasive techniques available in order to minimize pain, blood loss, and hospital stay, while maximizing recovery, neurologic function, and quality of life. In my free time, I enjoy spending time with my family and friends. I am an avid sports fan and love to eat. I try to stay physically fit by going to the gym and playing ice hockey.

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