147. Proximal junctional failure in primary thoracolumbar fusion/fixation to the sacrum/pelvis for adult symptomatic lumbar scoliosis: long-term follow-up of a prospective multicenter cohort of 160 patients

Abstract

<h3>BACKGROUND CONTEXT</h3> Proximal junctional kyphosis (PJK) is a common adverse event in adult spinal deformity (ASD) surgery. Proximal junctional failure (PJF) is a severe form of PJK that often warrants revision surgery. Previous reports on PJK/PJF have been limited by heterogeneous patient populations and relatively short follow-up. <h3>PURPOSE</h3> The objectives of this study were to better understand risk factors for PJF and assess its long-term incidence and revision rates in a prospectively-collected, homogenous patient population (primary adult symptomatic lumbar scoliosis [ASLS]) with long-term follow-up. <h3>STUDY DESIGN/SETTING</h3> Retrospective review of prospectively-collected multicenter patient cohort. <h3>PATIENT SAMPLE</h3> This study included 160 ASLS patients. <h3>OUTCOME MEASURES</h3> Occurrence of PJF; Patient-reported outcome measures (ODI, SRS-22r, SF-36). <h3>METHODS</h3> We reviewed data from ASLS-1, an NIH-sponsored multicenter prospective study. Inclusion criteria were: age=40 years with ASLS (Cobb >30° and ODI >20 or SRS-22 7 levels. PJF was defined as postop proximal junctional angle (PJA) change=20°, fracture of the upper-most instrumented vertebra (UIV) or UIV+1 with 20% vertebral body height loss, anterolisthesis of UIV/UIV +1 =3 mm, and/or UIV screw dislodgment. Demographic, clinical, radiographic and surgical data were collected. Comparative and multivariate analysis were performed comparing patients with and without PJF. <h3>RESULTS</h3> A total of 160 patients were included (mean age 61 yrs; 141 women) with mean follow-up of 4.3 yrs (range: 0.1-6.1 yrs). Forty-six patients (28.7%) developed PJF at a median of 0.92 yrs (interquartile range: 0.14-1.23 yrs) postop. PJF incidences at 1, 2, 3, and 4 yrs were 14.4%, 21.9%, 25.9%, and 27.4%, respectively. On univariate analysis, factors associated with PJF included greater age (p=0.03), greater body mass index (BMI; p=0.03), worse baseline PROMs (ODI; SRS-22r: subscore, pain, function, mental health; SF-36 PCS; all p <0.04), greater use of posterior column osteotomies (p=0.004), and worse TK (p=0.0031) and PJA (P <0.001 on first postop standing imaging. Use of hooks at the UIV was protective against PJF (p=0.03). On regression analysis (excluding postop imaging measures), factors associated with PJF were greater BMI (OR=1.077, 95%CI=1.007-1.153, p=0.03), lower preop PJA (OR=0.607, 95%CI=0.407-0.906, p=0.01), and greater preop TK (OR=1.362, 95%CI=1.082-1.715, p=0.009). Patients with PJF had significantly worse PROMs at last follow-up (ODI; SRS-22r subscore and self-image; SF-36 PCS; all p <0.04). Sixteen (34.8%) of the patients with PJF underwent revision surgery; recurrent PJF occurred in 3 of the 16. <h3>CONCLUSIONS</h3> In this homogenous population of primary ASLS patients, the PJF rate was 28.7% at mean 4.3-yr follow-up with a revision rate of 34.8%. Higher risk of PJF was associated with greater age and BMI, use of posterior column osteotomies, lower preop PJA, and greater preop TK. Use of UIV hooks was protective against PJF. These findings demonstrate that PJF remains a challenge and that new strategies to mitigate its occurrence are needed. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.