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

This study aimed to 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, noninvasive tool to help identify PSAR.

METHODS

This study included consecutive primary surgical patients with idiopathic or degenerative scoliosis undergoing anterior and posterior correction with instrumentation to the sacrum or pelvis and minimum 2-year follow-up. Patients were grouped into fused (no radiographic or clinical signs of PSAR) and PSAR (known PSAR diagnosed by surgical exploration or thin-cut computed tomography scan at least 1 year after surgery) cohorts. Two-year radiographs were graded by an independent blinded orthopedic deformity surgeon and a neuroradiologist. HRQOL scores [22-item Scoliosis Research Society questionnaire (SRS-22) and the Oswestry Disability Index (ODI)] at 1-year follow-up were analyzed as potential predictors of future PSAR.

RESULTS

Thirty-four patients with average follow-up of 2.2 years (2-2.5 y) were evaluated. Eight (23.5%) patients had known PSAR consisting of 40 (24.8%) anterior levels. Analysis by independent reviewers incorrectly identified 2 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 1-year postoperatively 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.

CONCLUSIONS

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.