Association of preoperative vertebral kyphosis and other factors with cement leakage after percutaneous kyphoplasty: a retrospective cohort study

BACKGROUND: Percutaneous kyphoplasty (PKP) is an established treatment modality for painful vertebral compression fractures; however, cement leakage remains its most frequent complication. Although factors such as cortical disruption and fracture type have been widely studied, the influence of preoperative sagittal deformity on leakage risk remains unclear. This study aimed to evaluate the association between preoperative vertebral kyphosis and cement leakage after PKP, with particular attention to CT-based bone quality. METHODS: We retrospectively reviewed patients who underwent PKP for thoracolumbar compression fractures. Bone quality was assessed using CT-derived Hounsfield unit (HU) measurements, and patients were stratified into two groups using a threshold of 114.8 HU: low HU (≤ 114.8) and high HU (> 114.8). Cement leakage was evaluated on routine postoperative CT scans. Radiologic parameters included vertebral kyphosis, segmental kyphosis, Beck index, and posterior wall involvement. To account for multiple procedures within the same patient, we used a generalized linear mixed-effects model (GLMM) with patient ID as a random effect. RESULTS: Cement leakage was detected in 57.4% of procedures (224/390). Leakage patterns included intradiscal leakage in 28.2%, venous leakage in 2.8%, anterior/lateral leakage in 9.5%, spinal canal leakage in 1.8%, and mixed leakage in 15.1%. Despite the relatively high radiographic leakage rate, all leakage events were clinically silent, with no symptomatic neurological deficits or embolic complications observed. In both HU groups, leakage was associated with greater preoperative vertebral kyphosis and a lower Beck index. In the low HU group, each 1° increase in preoperative vertebral kyphosis increased the odds of leakage by 7% (OR 1.07; 95% CI 1.02-1.12; p = 0.009), whereas surgery performed within 3 days was associated with a reduced risk of leakage (OR 0.36; 95% CI 0.14-0.90; p = 0.028). CONCLUSION: Although radiographic cement leakage was common after PKP, clinically significant complications were rare. An increased preoperative vertebral kyphosis may be associated with a higher risk of cement leakage and should be kept in mind during patient assessment. In addition, delayed intervention in patients with poor CT-based bone quality may be associated with an increased leakage risk.