P101. Distal junctional failure: a feared complication of adult spinal deformity surgery

Abstract

BACKGROUND CONTEXT Distal junctional failure DJF is a rarer and less extensively described complication than proximal junctional failure or kyphosis following adult spinal deformity (ASD) surgery. Multifactorial etiologies are reported for DJF and there is no consensus on which risk factors may contribute to it. PURPOSE The aim of this study was to describe a cohort of patients requiring revision surgery for DJF taking into account sagittal spinopelvic alignment and suggest potential risk factors in light of the current literature. STUDY DESIGN/SETTING Single-center retrospective cohort study. PATIENT SAMPLE Nineteen adult spinal deformity patients with distal junctional failure that required revision surgery. OUTCOME MEASURES Quantification of sagittal alignment correction after revision surgery and number of reoperations. METHODS We performed a single center retrospective review of adult spinal deformity patients who had any type of clinically and radiographically significant distal junctional failure and had to undergo revision surgery between June 2009 and January 2019. Demographic characteristics (age, gender, body mass index and comorbidities), and surgical details were collected to identify risk factors for DJF. Radiographical measurements included a preoperative and postoperative sagittal alignment analysis for each index or revision surgery, distal junctional sagittal Cobb angle and a coronal alignment analysis. The number of fused levels, location of upper instrumented vertebra (UIV), lower instrumented vertebra (LIV) and fusion length were recorded. A case-by-case analysis was performed to identify potential risk factors and main reasons for DJF in light of the current literature. RESULTS Nineteen revision cases due to distal junctional failure are reported. Mean age was 64.74 ± 13.55 years old and average follow-up was 4.7 ± 2.4 years (12 F, 7 M). The average number of instrumented levels was 6.79 ± 2.97. We observed that 84.2 % (n=16) of the patient sample had at least one risk factor for mechanical complications. The most frequently observed LIV was L5 in 10 cases while two patients had a LIV at S1 without pelvic fixation. Only six patients had a circumferential fusion performed in the first surgery. Most frequently observed DJFs were fracture below the fusion (n=2), L5 pull out (n=6), spinal stenosis and instability (n=8). The average time to revision surgery was 15.62 ± 17.86 months, eight cases being revised in the first postoperative year. The most frequent revision was the fusion to the pelvis. In our series, nine patients had to undergo a second revision procedure and three underwent a third revision surgery. After DJF, all patients were sagittally unbalanced. Revision surgery was able to partially restore SVA (60.43±55.24 mm at DJF vs 37.64±34.4 mm postoperatively). CONCLUSIONS Our data supports that female gender, osteoporosis, stopping at L5 or at S1 without iliac fixation in long constructs with UIV proximal to L1 represent a high risk of DJF. Insufficient sagittal balance restoration also probably represents a high risk of DJF and revision surgery. Restoring spinal balance (hardware revision, correction and extension of fusion) and obtaining a solid fusion at the lower extremity of constructs (pelvic fixation, possible anterior column support) represent key steps. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.