The use of hooks in upper instrumented vertebra to prevent proximal junctional complications: a systematic review and meta-analysis.

BACKGROUND: Proximal junctional kyphosis (PJK) and proximal junctional failure (PJF) are leading complications after adult spinal deformity (ASD) surgery. Proximal hooks at the upper instrumented vertebra (UIV) may reduce stiffness transition and PJK/PJF risk, but comparative evidence is limited. This systematic review and meta-analysis evaluates the association between hook use and PJK/PJF incidence. METHODS: A comprehensive literature search was conducted using PubMed, Cochrane Library, and SpringerLink from 2000 to 2025. Studies related to the use of hooks versus other fixation methods (e.g., pedicle screws) in preventing PJK/PJF were compared and included. Data were extracted and analyzed. Risk of bias and publication bias was assessed using funnel plots and Egger’s test. Pooled estimates were calculated using random-effect models. RESULTS: Meta-analysis was conducted on five studies comprising 1,131 patients. For proximal junctional kyphosis (PJK; 2 studies, n = 183), hook fixation showed a trend toward lower incidence (22.0% vs. 29.1%) but did not reach statistical significance (RR 0.76, 95% CI 0.46–1.25, p = 0.28). For proximal junctional failure (PJF; 3 studies, n = 948), hooks significantly reduced incidence (6.9% vs. 25.3%; RR 0.32, 95% CI 0.17–0.59, p < 0.001). Combined analysis of all five studies demonstrated a significant overall protective effect of hooks against proximal junctional complications (RR 0.50, 95% CI 0.31–0.82, p < 0.05). No significant publication bias was detected. CONCLUSIONS: Hook fixation at the upper instrumented vertebra significantly reduced proximal junctional failure (PJF) by 68% (RR 0.32, p < 0.001) compared to pedicle screws alone. For proximal junctional kyphosis (PJK), a non-significant trend favored hooks (RR 0.76, p = 0.28). These findings support hooks as a protective strategy against clinically significant junctional complications, particularly PJF, in adult spinal deformity surgery.