Risk Factors for Adjacent Fractures After Cement-Augmented Thoracolumbar Pedicle Screw Instrumentation.

Background: The aim of our study was to identify factors that influence the occurrence of adjacent fractures in patients with cement-augmented pedicle screw instrumentation.

Methods: Data were retrospectively collected from medical charts and operative reports for every surgery in which cement-augmented instrumentation was used in our hospital of 4 consecutive years. A total of 93 operations were included and examined for gender, age, T-score, number of fused segments, number of implanted screws, broken screws, loosening of screws, leakage and distribution pattern of cement, pre- and postoperative kyphosis angle, revision surgery and adjacent fractures in follow-up. Categorical data were compared using the χ2 test or by Fisher's exact test, as appropriate. Continuous variables conforming to a normal distribution were compared using Student's t test. Otherwise the Mann-Whitney U test was applied. A P -value of <.05 was considered statistically significant. A trend was defined as a P < .2.

Results: The mean age was 68.1 years with a mean T-score of -3.12. Nineteen adjacent fractures occurred during follow-up and the median follow-up was 12 months (range, 1-27). Patients showed a higher risk for adjacent fractures following revision surgery ( P = .016). Most fractures occurred superior to the instrumented level ( P = .013) and in the first 12 months. Difference of T-score between the group "no adjacent fracture" and the group "adjacent fracture" was 0.7 ( P = .138). Another trends were found in greater age ( P = .119) and long instrumentations ( P = .199).

Conclusions and Clinical Relevance: Revision surgeries are associated with a higher risk of adjacent fractures. In these cases, prophylactic kyphoplasty of the superior vertebra should be considered. This study is a retrospective, nonrandomized cohort/follow-up study.

Level of Evidence: 3.