A propensity-matched comparison of risk factors for proximal junctional failure (PJF
), which is a symptomatic proximal junctional kyphosis developing after corrective surgery for adult spinal deformity
To elucidate the role of bone strength for developing PJF
Summary of Background Data. PJF
, a devastating complication of corrective surgery for ASD, often recurs even after revision surgery. Most studies of risk factors for PJF
are retrospective and have a selection bias in surgical strategy, making it difficult to identify modifiable PJF
We conducted propensity-matched comparisons of 113 surgically treated ASD patients who were followed for at least 2 years, to elucidate whether low bone-mineral density (BMD
) was a true risk factor
in a uniform population from a multicenter database. Patients were grouped as having mildly low to normal BMD
(M group; T-score≧ − 1.5) or significantly low BMD
(S group; T-score < −1.5), and were propensity-matched for age, upper and lower instrumented vertebrae, history of spine surgery, and Schwab-Scoliosis Research Society (SRS) ASD classification. PJF
was defined as a ≥20° increase from the baseline proximal junction angle with a concomitant deterioration of at least one SRS-Schwab sagittal modifier grade, or any type of proximal junctional kyphosis requiring revision.
developed in 22 of 113 patients (19%). There were 48 propensity-matched patients in the M and S groups (24 in each) with similar parameters for age, body mass index, number of vertebrae involved, C7SVA, pelvic incidence − LL, and SRS-Schwab type. In this propensity-matched population, the incidence of PJF
was significantly higher in the S group (33% vs.
< 0.01, odds ratio 6.4, 95% CI: 1.2–32.3).
was a significant risk factor
in this propensity-matched cohort (odds ratio 6.4). Surgeons should consider prophylactic treatments when correcting ASD in patients with low BMD
Level of Evidence: 3