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SUMMARY OF BACKGROUND DATA Differing presentations of adult spinal deformity(ASD) may influence the extent of surgical intervention and use of prophylaxis at the base or the summit of a fusion construct to influence junctional failure rates. OBJECTIVE Evaluate the surgical technique that has greatest influence on the rate of junctional failure following ASD surgery. STUDY DESIGN/SETTING Retrospective. METHODS ASD patients with two-year(2Y) data and at least 5-level fusion to pelvis were included. Patients were divided based on UIV: [Longer Construct:T1-T4; Shorter Construct:T8-T12]. Parameters assessed included matching in age-adjusted PI-LL or PT, aligning in GAP-Relative Pelvic Version or Lordosis Distribution Index. After assessing all lumbopelvic radiographic parameters, the combination of realigning the two parameters with the greatest minimizing effect of PJF constituted a Good Base. Good Summit defined as having: (1)prophylaxis at UIV(tethers,hooks,cement), (2)no lordotic change(under-contouring) greater than 10° of the UIV, (3)preoperative UIV inclination angle<30°. Multivariable regression analysis assessed effects of junction characteristics and radiographic correction individually and collectively on development of PJK and PJF in differing construct lengths, adjusting for confounders. RESULTS 261 patients were included. The cohort had lower odds of PJK(OR: 0.5,[0.2-0.9];P=0.044) and PJF was less likely (OR: 0.1,[0.0-0.7];P=0.014) in the presence of a Good Summit. Normalizing pelvic compensation had the greatest radiographic effect on preventing PJF overall (OR: 0.6,[0.3-1.0];P=0.044). In Shorter Constructs, realignment had greater effect on decreasing the odds of PJF(OR: 0.2,[0.02-0.9];P=0.036). With Longer Constructs, a Good Summit lowered likelihood of PJK(OR: 0.3,[0.1-0.9];P=0.027). Good Base led to zero occurrences of PJF. In patients with severe frailty/osteoporosis, a Good Summit lowered incidence of PJK(OR: 0.4,[0.2-0.9]; P=0.041) and PJF (OR: 0.1,[0.01-0.99];P=0.049). CONCLUSION To mitigate junctional failure, our study demonstrated the utility of individualizing surgical approaches to emphasize an optimal basal construct. Achievement of tailored goals at the cranial end of the surgical construct may be equally important, especially for higher risk patients with longer fusions. LEVEL OF EVIDENCE III.