Listhesis and Spinopelvic Inclination of Upper Instrumented Vertebra Region and the Implications on Proximal Junctional Kyphosis.

STUDY DESIGN: Retrospective analysis of prospective data. OBJECTIVE: Evaluate the impact of radiographic and morphologic configuration of the uppermost instrumented vertebrae (UIV) region on proximal junctional kyphosis (PJK) rates. BACKGROUND: Literature is limited on evaluation of the preoperative landing zone (UIV-1 to UIV +2 levels) and its impact on development of PJK. METHODS: Adult ASD patients with native baseline thoracolumbar junction, postoperative UIV between T9-T12 and LIV extending to pelvis, and 2-year follow-up available were included. Landing zone was assessed on radiographs for Meyerding grade listhesis and posterior translation angle by 2 spine surgeons. Comparative analyses were performed on demographics, radiographic parameters, and PJK rates across patients with/without landing zone listhesis and above/below 15° UIV spinopelvic inclination (UIV SPi). Multivariable regression, accounting for listhesis, UIV SPi, PJK prophylaxis, age, osteoporosis, radiographic UIV quality (bridging osteophytes/degenerative disc disease) and change in PI-LL and SVA, was used to identify independent predictors of PJK. RESULTS: Among 244 patients, mean age was 64.41 years, 73.0% were female, mean CCI was 1.97. In total, 30% had preoperative landing zone listhesis and 42% had posterior translation (41% with baseline posterior translation and 59% with iatrogenic translation). Listhesis patients had similar baseline and 2-year radiographic alignment but higher 2-year PJK rates (32.9% vs. 20.5%, P=0.04). UIV SPi>15° patients also had higher PJK (37.5% vs. 14.2%, P<0.01) and PJK reoperation (16.3% vs. 5.8%, P=0.01) rates. Patients with both listhesis and UIV SPi>15° had the highest PJK (45.5%, P=0.03) and PJK reoperation (21.1%, P=0.18) rates. Multivariable regression (R2=0.33) identified landing zone listhesis (coeff=1.0, P=0.01) and UIV SPi (coeff=-0.22, P<.001) to be predictive of PJK. CONCLUSIONS: Preoperative listhesis and postoperative posterior translation are independent predictors of 2-year PJK. These findings highlight the importance of meticulous selection of the UIV landing zone, with particular emphasis on preoperative listhesis and spinopelvic inclination. LEVEL OF EVIDENCE: IV.

Duke Scholars

Author Christopher Ignatius Shaffrey Orthopaedic Surgery

Author Peter Passias Orthopaedic Surgery