Detection of Pseudarthrosis in Adult Spinal Deformity: The Use of Health-related Quality-of-life Outcomes to Predict Pseudarthrosis.

STUDY DESIGN: Single-center, retrospective study of consecutive surgeries.

OBJECTIVE: Evaluate the reliability of previously published anterior fusion grading systems and assess the ability of health-related quality-of-life (HRQOL) outcomes to predict pseudarthrosis (PSAR).

SUMMARY OF BACKGROUND DATA: Despite existing radiographic indicators, PSAR may still go unidentified on biplanar radiographs, and little data is available on the reliability of such grading systems in adult spinal deformity patients. As such, there is a need for a practical, non-invasive tool to help identify PSAR.

METHODS: Consecutive primary surgical patients with idiopathic or degenerative scoliosis undergoing anterior and posterior correction with instrumentation to the sacrum or pelvis and minimum two-year follow-up. Patients grouped into Fused (no radiographic or clinical signs of PSAR) and PSAR (known PSAR diagnosed by surgical exploration or thin cut CT scan at least one year after surgery) cohorts. Two-year radiographs were graded by an independent blinded orthopedic deformity surgeon and a neuroradiologist. HRQOL scores (SRS-22 and ODI) at one-year follow-up were analyzed as potential predictors of future PSAR.

RESULTS: 34 patients with average follow-up of 2.2 years (2-2.5) were evaluated. Eight (23.5%) patients had known PSAR consisting of 40 (24.8%) anterior levels. Analysis by independent reviewers incorrectly identified two levels as unfused and failed to identify any PSAR levels. The PSAR group had lower average SRS scores in all domains and lower average ODI scores at one-year post-op relative to fused patients. The PSAR group also showed no significant improvement in SRS or ODI scores relative to baseline. In comparison, the fused group showed significant improvement in all domains.

CONCLUSION: Standard radiographs are insufficient for identifying PSAR in adult spinal deformity patients. Failure to achieve significant improvement in SRS and ODI should lead the surgeon to suspect PSAR and consider additional investigation.