40. Long-term radiographic outcomes following adult spinal deformity surgery

Abstract

BACKGROUND CONTEXT Sagittal balance in adult spinal deformity is topic of ongoing exploration. Junctional kyphosis and junctional failure are challenging problems whose contributing factors are not entirely understood. A high native pelvic incidence has been shown to be a risk factor for adjacent segment disease. Recent developments in sagittal plane measures include the T1 pelvic angle which was proven to correlate with health-related quality of life scores. PURPOSE To evaluate whether a high preoperative pelvic incidence, postoperative pelvic incidence-lumbar lordosis mismatch, or postoperative T1-pelvic angle is predictive of proximal junctional kyphosis or failure and subsequent revision or persistent pain at long-term follow-up. STUDY DESIGN/SETTING A multicenter, multisurgeon retrospective cohort study. PATIENT SAMPLE All patients who underwent a posterior thoracolumbar fusion with pelvic fixation, with or without interbody fusion, with or without three-column osteotomy between 2010-2019. OUTCOME MEASURES Outcome measures included radiographic evaluation of PJK or PJF, sagittal alignment, adjacent segment disease, revision rate, and back pain needing opiates, pain management, or documentation of surgical revision counseling at or before long-term follow-up. METHODS Patients were separated into cohorts of preoperative pelvic incidence less than or equal to 55° and greater than 55°. -term follow-up ranged from 1 to 8 years post index surgery. Pelvic incidence, lumbar lordosis, T1-pelvic angle, and proximal junctional angle were recorded at preoperative, short term postoperative (less than 3 months) and Long-term postoperative (over 1 year) follow-up. At Long-term follow-up the revision rate and patient symptoms were recorded as well as radiographic parameters. Multivariate statistical analysis is being conducted. RESULTS Preliminary data indicates that 60% of patients with a high native pelvic incidence had evidence of PJK or PJF at or prior to Long-term follow-up. No patients with a low pelvic incidence had junctional kyphosis at Long-term follow-up. Of patients with a T1-pelvic angle over 20°, 55% had evidence of PJK or PJF. The overall rate of revision surgery, continued pain or deformity was 87% in patients with a T1-pelvic angle over 20°. No patients with a T1-pelvic angle less than 20° had PJK or PJF and one patient in this cohort developed symptomatic adjacent segment disease. CONCLUSIONS A native pelvic incidence over 55° may be predictive of Long-term junctional kyphosis and symptomatic adjacent segment disease. A postoperative T1-pelvic angle greater than 20° degrees is associated with continued back pain and revision surgery following thoracolumbar fusions at up to 8 years post surgery. Interestingly, despite correction of PI-LL mismatch within 9° at the short term follow-up, the T1 pelvic angle tended to return to within 10° of the initial preoperative measure in the majority of cases at Long-term follow-up suggesting that the pursuit of sagittal plane correction to meet defined spinopelvic parameters may not account for physiologic kyphosis with increasing age. Data collection is ongoing to meet power analysis and statistical significance criteria. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.