Background <p>Polymethylmethacrylate (PMMA) augmentation of pedicle screws is a common technique to improve fixation in patients with poor bone quality. However, it can lead to complications such as cement leakage and pulmonary embolism. Although most cases are asymptomatic, apprehension about serious complications frequently results in unnecessary interventions and delayed enhanced recovery protocols. This study aimed to determine the incidence, associated factors, and clinical impact of cement leakage and pulmonary cement embolism in cement-augmented spinal instrumentation.</p> Methods <p>We retrospectively reviewed 137 patients who underwent cement-augmented spinal instrumentation between 2009 and 2019, selected from a prospective cohort of 561 cases. Only patients with a postoperative chest computed tomography (CT) scan performed for any reason were included, with a minimum follow-up of 12 months. Demographic variables, number and level of cemented vertebrae, bone mineral density (T-score), and the presence of cement leakage or pulmonary embolism were recorded.</p> Results <p>Cement leakage occurred in 67.9% of patients, mainly through segmental veins (82.8%). Leakage correlated with the number of cemented vertebrae (<i>p</i> = 0.03; 95% CI: 1.12–1.41), but not with vertebral level or T-score. Pulmonary cement embolism was detected in 56.2% of cases, while only one patient (0.72%) developed a symptomatic cement embolism.</p> Conclusions <p>Cement leakage and pulmonary cement embolism are frequent but mostly asymptomatic. Supportive treatment should be reserved for symptomatic or haemodynamically unstable patients. Further research is needed to optimise prevention, diagnosis, and management strategies.</p>