The Clinical Outcomes of Operative Treatment Versus Conservative Treatment for Dancer’s Fractures: Protocol for a Retrospective Cohort Study
Authors: de Ruijter Marinus Alexander , Yuan Jian Zhang , Derksen Robert Jan 
Published: April 2022

Background
Fifth metatarsal fractures are one of the most common foot fractures, and 11% to 25% of such fractures are Dancer’s fractures (distal spiral fractures). Conservative therapy while wearing a cast and operative treatment have been used as preferred modes of treatment in the limited literature available. However, we often see healing problems, such as delayed union and nonunion, when Dancer’s fractures are treated nonoperatively, resulting in a need for secondary intervention. In our institution, treatment has changed over the years from predominantly conservative treatment to mostly operative treatment. To investigate whether our hypothesis holds true that primary surgical treatment is beneficial, a retrospective study was designed.

Objective
The objective of the study is to compare differences between outcomes (delayed union and nonunion) of conservative and operative treatments for Dancer’s fractures.

Methods
A retrospective comparative cohort study will be conducted in a level II trauma center (Zaandam Medical Center). Patients who experienced a Dancer’s fracture in the period of 2012 to 2021 will be included and divided into 2 cohorts—the conservative (2012-2015) and operative (2016-2021) treatment cohorts. The primary outcome will be the differences in percentages of delayed union and nonunion between the two groups. The secondary outcomes will be the percentage of primary conservative treatment failure, the need for secondary operative treatment, complications (infection and hardware failure), and functional outcomes. If 118 patients are included in each group, sufficient power is expected to be reached, depending on the age distribution of patients. The percentages of delayed union and nonunion among the two groups will be calculated and statistically compared via chi-square statistics. A logistic regression analysis will be used to investigate possible associations between patient characteristics and failed conservative treatment. A Mann-Whitney U test will be used to compare functional outcomes between groups. An independent, 2-tailed t test will be used to compare mean 12-Item Short Form Survey scores if they are normally distributed, and a Wilcoxon rank sum test will be used if they are nonnormally distributed.

Results
In total, 2134 potentially relevant health insurance codes have been extracted from the hospital’s register. We expect to find a total of 236 Dancer’s fractures in this data set.

Conclusions
Our study has limitations due to it being a single-center study and data collection being performed retrospectively. However, it covers a large time period and may provide the possibility to show treatment outcome differences (delayed union and nonunion, complications, and functional outcomes) in 2 reasonably large cohorts (conservative and operative treatment cohorts), which has not been done before in literature on Dancer’s fractures. If our hypothesis that surgery is beneficial for Dancer’s fractures is proven true by our study, we plan to further corroborate it by conducting a prospective randomized controlled trial.

International Registered Report Identifier (IRRID)
PRR1-10.2196/37171