General Session: Adult Spinal Deformity

Presented by: B. Liabaud - View Audio/Video Presentation (Members Only)


M. Gupta(1), B. Liabaud(2), J. Henry(3), V. Lafage(2), F. Schwab(2), C. Ames(4), E. Klineberg(1), J. Smith(5), V. Deviren(1), C. Shaffrey(5), R. Hart(6), R. Hostin(7), G. Mundis(8), H.J. Kim(2), D. Burton(9), International Spine Study Group

(1) UC Davis Health System, Sacramento, CA, United States
(2) Hospital for Special Surgery, New York, NY, United States
(3) NYU Hospital for Joint Diseases, New York, NY, United States
(4) UCSF, San Francisco, CA, United States
(5) University of Virginia, Charlottesville, VA, United States
(6) OHSU, Portland, OR, United States
(7) Baylor Scott & White Health, Texas, TX, United States
(8) San Diego Center for Spinal Disorders, La Jolla, CA, United States
(9) The University of Kansas Hospital, Kansas, KS, United States


Purpose: To investigate if the addition of supplementary rods, IBF, or rod material/diameter decrease the failure rate.

Introduction: Pedicle subtraction osteotomies (PSO) can provide substantial realignment, but are associated with nonunion and rod failure. The addition of supplementary rods and interbody fusion (IBF) may decrease the failure rate.

Methods: Adult spinal deformity patients with at least 1 lumbar PSO and 2-year follow-up were included. Demographic, operative, and radiographic data were collected. The number of rods across the PSO site was reviewed; more than 2 rods were categorized as accessory (A: connected to primary rods) or satellite (S: independently anchored). Potential risk factors were evaluated for PSO site failure (rod breakage or revision for nonunion).

Results: In 264 patients included, rod configurations were: 2 rods (2R)=190, 3R=36, 4R=38. There were no differences in demographics or sagittal alignment across groups. 2-3R had a trend of higher rates of failure (28%, 29%) than 4R (18%; P=0.128). In 3-4R constructs, S rods had significantly lower failure rates than A rods (10% vs 31%; P=0.034); accessory rods were similar to 2R (31% vs 29%; P=0.452). In 3-4R constructs, larger rod diameter (≥6.0mm) failed significantly less than 4.5-5.5mm rods (5% vs 33%; P=0.011). In 2R constructs, Ti rods had a significantly higher rate of breakage/nonunion (44%) than CC and SS (25%, 24%; P=0.037). There was no difference in failure by material in the 3-4R constructs (P=0.127). IBF at the PSO level resulted in fewer failures overall (21% vs 33%; P=0.046), and for 2R (22% vs 34%; P=0.112), 3-4R (16% vs 31%; P=0.164), and S (0% vs 27%; P=0.050) constructs.

Conclusions: This study confirms a high rate of nonunion and rod breakage in the 2 years following lumbar PSO surgery. The lowest rates of rod failure/nonunion were found in constructs with satellite rods, IBF adjacent to the PSO, and larger diameter rods.