Pediatric Tibial Tubercle Fracture-Associated Compartment Syndrome: Response

Dear Editor,

Thank you for allowing me to respond to the letter to the editor submitted in response to our study titled “Assessing the Rate and Risk Factors of Compartment Syndrome in Pediatric Tibial Tubercle Fractures.” ¹ This is an important topic relevant to pediatric orthopedic surgeons, as well as general orthopedic surgeons taking pediatric orthopedic call. Previous studies have highlighted the risk of acute compartment syndrome (ACS) in the setting of tibial tubercle fractures in children; however, these studies have been limited by small sample sizes and selection bias.

Administrative data allow for the study of large patient cohorts but have several limitations, as the letter writers note. For example, misclassification, coding inaccuracy, and the lack of clinical data are important limitations, and my co-authors and I specifically listed these as limitations in our “Discussion” section. The type of database used for a study matters; it is important to consider the research question and study population when selecting a database for clinical research. ² For this study, we aimed to assess the epidemiology of this condition and decided to use the Pediatric Health Information System database, which is derived from major children’s hospitals that presumably see the highest volume of pediatric tibial tubercle fractures. Due to the limitations of this database, we stratified patients into 3 groups based on procedure and diagnosis codes to estimate the true incidence of ACS, analogous to a sensitivity analysis. The true incidence is likely in the 1% to 4% range, and the findings from this study are consistent with previous literature on this topic. However, I agree with the letter writers that retrospective and prospective multicenter studies with clinical data are needed to better assess the incidence and risk factors of ACS in pediatric tibial tubercle fractures.

Lastly, this study attempted to identify risk factors for ACS in the setting of this injury. We found that older age was significantly associated with a higher risk, as has been shown in a previous study. ³ I agree with the letter writers that our study is likely underpowered to assess other risk factors, and we could not assess more specific risk factors that may be associated with ACS. Clinically, it is important to consider factors such as the mechanism of injury and the time of injury, which cannot be ascertained in a database study. Our study was intended to be hypothesis-generating and allow for future studies on this important topic.

In summary, I thank the letter writers for highlighting the issues related to database studies in clinical orthopedic research. I would like to underscore the importance of choosing appropriate research questions for administrative databases; selecting the appropriate database to study that question; and highlighting limitations of the database in each study. I am hopeful that studies such as ours will inform additional studies of higher quality to definitively answer important clinical questions.