Pseudarthrosis in Long Adult Spinal Deformity Instrumentation and Fusions to the Sacrum: Incidence and Risk Factor Analysis of 149 Cases
Purpose: To analyze the incidence of and risk factors for pseudarthrosis in long adult spinal instrumentation and fusion to S1.
Methods: A clinical and radiographic assessment of 149 adult spinal deformity patients (average age 51.0 years) who underwent long (> 5 vertebrae) spinal instrumentation and fusion to the sacrum with a minimum 2-year follow up (average 3.9 years; 2-14 years) was analyzed. Pseudarthrosis was defined as a segmental motion during exploration or implant failure. Complete sacropelvic fixation was defined as bilateral L5, S1 and iliac screw fixation in addition to anterior structural L5-S1 graft.
Results: 35 patients had pseudarthroses (24%). 17 patients (48%) demonstrated pseudarthroses at L5- S1. Pseudarthrosis was most commomly detected within four years postoperation (33 patients; 94%). Factors which statistically increased the risk of pseudarthrosis were as follows: Thoracolumbar kyphosis (T10-L2 ³20º) (p<0 .001) and osteoarthritis of the hip joint (p="0.044)" Fusion from upper thoracic spine (T2-T5) did not statistically increase pseudarthrosis rate compared to lower (T9-12) With L5-S1 pseudarthrosis, incomplete sacropelvic fixation (23%, 9 pseudos/ 39 patients) demonstrated a significantly higher pesudarthrosis than complete (9%, 8 90 Osteoarthritis joints also correlated. Patients with had total SRS-24 outcome score (average score, 75/120) those without 87/120; p="0.010)."
Conclusion: The overall incidence of pseudarthrosis following long adult spinal deformity instrumentation and fusions to S1 was 24%. L5-S1 was the most common area. Thoracolumbar kyphosis, osteoarthritis of the hip joint, and incomplete sacropelvic fixation (especially for pseudarthrosis of L5-S1) significantly increased the risks of pseudarthrosis to an extent that was statistically significant. SRS-24 outcomes scores were adversely affected when pseudarthrosis developed.