Proximal junction uninstrumented bone fusion for proximal junctional kyphosis/failure prevention: a retrospective matched cohort study in Korea.

Abstract

Retrospective matched cohort study. This study aimed to determine the efficacy of proximal junction uninstrumented bone fusion (UBF) to prevent proximal junctional kyphosis/failure (PJK/F) in adult spinal deformity (ASD) surgeries. PJK/F represents significant complications in ASD surgeries. Despite many preventive strategies being developed, which have been largely categorized as additive surgical procedures and optimal alignment correction, PJK/F still remains a prevalent complication. This study retrospectively analyzed patients who underwent ASD corrective surgeries incorporating UBF at the proximal junction at a single academic institution. The patients with ASD were individually matched (1:2) for age, gender, osteoporosis status, and uppermost instrumented vertebrae. The demographic, operative, and radiographic parameters were compared, while the complication-free periods for PJK/F and any mechanical failure (MF) were separately assessed. A multivariable survival analysis identified the significant factors for mechanical complications. A total of 21 patients in the UBF group and 42 patients in the non-UBF group were enrolled. No significant differences in the demographic, operative, and radiographic parameters and the patient-reported outcome scores were observed. The median time to PJK/F was longer in the UBF group (11.0 months vs. 3.5 months, p=0.037). In the UBF group, six patients had successful bone mass fusion without any MF. The odds ratio of UBF was 0.55 (p=0.28) for PJK/F and 0.35 (p=0.056) for any MF. The results of the Kaplan-Meier analysis indicated a significantly extended MF-free period in the UBF group (p=0.028), but not for PJK/F (p=0.16). Although proximal junction UBF in ASD surgeries did not show a statistically significant PJK/F reduction, its safety, technical simplicity, and the absence of complications in patients with successful bone mass fusion suggest its potential clinical value and warrant further research.