Preventive Effects of Cement and Hook Augmentation on Proximal Junctional Kyphosis Development in Adult Spinal Deformity Surgery: Multiple Regression Analyses With Adjustment for Confounding Factors

BACKGROUND AND OBJECTIVES: – Cement augmentation and hook fixation are popular prophylactic techniques against proximal junctional kyphosis (PJK) development. However, the efficacy of cement and hook has been inconsistent and conflicting. This study investigated the prophylactic effects of cement and hook augmentation in preventing PJK after adult spinal deformity surgery.METHODS: – We included patients undergoing ≥7-level fusion including sacrum for adult spinal deformity. The patients were divided into 3 groups: no-augmentation, cement, and hook groups. PJK was evaluated as mild (proximal junctional angle [PJA] 10°-27°) or severe (PJA ≥28°) PJK according to the PJA. In addition, patients undergoing revision surgery were assigned to severe PJK. Multivariate regression analyses were performed, including confounding variables, which showed significant differences between the no-augmentation and cement groups and between the no-augmentation and hook groups on comparison of baseline and perioperative radiographic data.RESULTS: – Altogether, 227 patients were included in the study (female, 90.1%; mean age, 69.7 years; total levels fused, 8.6). There were 105, 79, and 68 patients in the no-augmentation, cement, and hook groups, respectively. Multivariate analysis revealed that no use of cement augmentation did not increase the risk of PJK (odds ratio [OR] = 0.818, P = .706 for mild PJK; OR = 3.483, P = .087 for severe PJK). Multivariate analysis for hook fixation showed that no use of hook fixation did not affect the development of mild PJK (OR = 1.057, P = .891), but significantly increased the risk of severe PJK (OR = 8.287, P = .004).CONCLUSION: – Cement augmentation did not prevent PJK development in the bivariate and multivariate analyses. The preventive effect of hook fixation on PJK development was not significant in unadjusted bivariate analysis. However, hook fixation significantly mitigated the risk of severe PJK in the confounder-adjusted multivariate analysis.