Loosening, Failure, and Revision in Adult Deformity Surgery

Lumbopelvic fixation failure rates are high following adult spinal deformity correction and are associated with lesser clinical improvements, according to a new multi-center U.S. study.

Traditional iliac and S2-alar-iliac (S2AI) pelvic fixation methods for correcting adult spinal deformity are unique techniques that can affect the body differently leading, potentially, to different lumbopelvic fixation failure types and rates, the study authors said.

The team found that S2AI screws were more likely to be associated with loosening, but less frequently with rod fractures at the lumbopelvic region.

The study, “Rates of Loosening, Failure, and Revision of Iliac Fixation in Adult Deformity Surgery,” was published online on July 15, 2022 in the journal Spine.

In this retrospective cohort review of a prospective multicenter patient surgery database, the researchers collected data on rates and variations for lumbopelvic fixation failure after adult spinal deformity correction.

The patients who were undergoing correction with more than five level fusion and pelvic fixation were separated by pelvic fixation, traditional iliac, and S2-alar-iliac. The team then collected data regarding rates of screw loosening/fracture, rod fracture, and revision surgery.

Of 1,422 patients, 418 were included in the study. There were 287 patients in the traditional iliac fixation group and 131 in the S2AI group. The two groups had similar scores in baseline health related quality of life (HRQL) measure, Oswestry Disability Index, Scoliosis Research Society, and numeric rating scale leg and back, p > 0.05) and as well as in deformity (pelvic tilt, pelvic incidence-lumbar lordosis, and sagittal vertical axis, p > 0.05).

The iliac fixation group had more unilateral fixation versus S2-alar-iliac (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 2.63, p = 0.001; OR 6.05, p = 0.022).

The researchers also noted that while pelvic screw (2.3%) and rod fracture (14.0%) rates were similar between groups, there was a trend toward less occurrence with S2AI (OR 0.47, p =0.06).

In addition, 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 was associated with worse HRQL scores (physical component score 36.23 vs. 39.37, p = 0.04; ODI 33.81 vs. 27.93, p = 0.036), and less 2 years improvement (physical component score 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).

The study authors include Robert K. Eastlack, M.D., Alex Soroceanu, M.D., Gregory M. Mundis, Jr., Alan H. Daniels, M.D., Justin S. Smith, M.D., Ph.D., Breton Line, BSME, Peter Passia, M.D, Pierce D. Nunley, M.D., David O. Okonkwo, M.D., Ph.D., Khoi D. Than, M.D., Juan Uribe, M.D., Praveen V. Mummaneni, M.D., MBA, Dean Chou, M.D., Christopher I. Shaffrey, M.D, Shay Bess, M.D., and the International Spine Study Group.

The researchers are associated with Scripps Clinic, La Jolla, CA, San Diego Spine Foundation, San Diego, CA, University of Calgary, Calgary, Canada, Brown University, Providence, RI, University of Virginia, Charlottesville, VA, Denver International Spine Center, Denver, CO, Rocky Mountain Hospital for Children, Denver, CO, Presbyterian/St. Luke’s Medical Center, Denver, CO, New York Spine Institute, New York, NY, New York University Medical Center/New York University School of Medicine, New York, NY, Spine Institute of Louisiana, Shreveport, LA, University of Pittsburgh, Pittsburgh, PA, Duke University, Raleigh, NC, Barrow Neurological Institute, Phoenix, AZ, and the University of California, San Francisco, CA.