General Session: Adult Spinal Deformity-2

Presented by: C. Cain - View Audio/Video Presentation (Members Only)


C. Barton(1), A. Noshchenko(1), V. Patel(1), C. Cain(1), C. Kleck(1), E. Burger(1)

(1) University of Colorado Anschutz Medical Campus, Denver, CO, United States


Purpose: Osteotomies including pedicle subtraction (PSO) and Smith-Peterson (SPO) are widely used to facilitate correction in the treatment of adult spinal deformity (ASD), but are associated with mechanical complications (MC). The purpose of this study was to determine the incidence and risk factors for mechanical complications after osteotomy for adult spinal deformity.

Study Design: Retrospective review of adult deformity database (COMIRB #14-1258).

Methods: Retrospective review of ASD database yielded 83 consecutive ASD patients (55 female, avg. age 58) meeting strict inclusion/exclusion criteria and follow up of at least 1 year or incidence of MC. Data was extracted for each operation including patient variables, surgical variables, instrumentation variables, and postoperative variables. Operations were divided into groups based on MC (e.g. proximal junctional failure (PJF) vs. non-PJF) and odds ratios were calculated to assess risk factors for specific MCs.

Results: Incidence of MC occurred in 32/83 (39%) of patients following 37/90 (41%) of osteotomy operations and trended higher in PSO 49% (24/49) vs. SPO 32% (13/41) (p=.13). Number of operations with specific MCs: 13 with loose screws, 11 PJFs, 10 pseudarthrosis, 7 subsequent adjacent decompressions, 5 broken rods, 5 compression fractures, 4 isolated pedicle fractures, 4 uncoupling of instrumentation, 1 sacral fx, 1 screw fx, and 1 osteotomy displacement. Risk factor meeting statistical significance for entire MC group was postop lumbar lordosis (LL) < 49 degrees (OR=2.53, p=.04). Statistically significant risk factors for MCs: Loose screws risk factor of fusion crossing lumbosacral junction (OR=7.66, p=.05); PJF risk factors were ever smoker (OR=8.76, p=.04) and presence of 2 or more cross-links (OR=3.87, p=.04); subsequent decompression surgery risk factor was fusion stopping above sacrum (OR=13.92, p=.02).

Conclusions: Current study shows incidence of mechanical complications occurred in 39% of patients following osteotomy and trends higher in PSO vs. SPO. Postop LL < 49 degrees was found to be a risk factor for all mechanical complications. Fusion across the lumbosacral junction was found to be a risk factor for loose screws. Ever smoking and presence of 2 or more cross-links were found to be risk factors for PJF. Fusion stopping above the sacrum was found to be a risk factor for subsequent decompression surgery.