Brace Versus Casting in Pediatric Low Risk Ankle Fractures

Objective: To determine if a removable ankle brace is at least as effective as casting in children between 5 and 18 years old with low-risk ankle fractures.

Rationale: Ankle injuries are very common among children. The Canadian Health Injury Reporting and Prevention Program reports approximately 5500 ankle injuries per year in children presenting to the 16 participating emergency departments, 35% of which are fractures. The majority of ankle injuries in children, including ankle fractures, have an excellent prognosis with a very low risk for any complications. We have recently shown that a predefined structured 'low-risk' clinical exam reliably identifies these low risk injuries, while simultaneously excluding 100% of high-risk fractures. This clinical rule reduces the need for radiography in children with ankle injuries by 63%. However, all low-risk injuries are currently not managed uniformly. Low-risk ankle fractures are often treated with a cast while soft tissue injuries are treated in a brace. Due to this distinction in management, many physicians still feel compelled to do radiographs in children with low risk ankle injuries in order to identify the fractures. We will now expand our previous work to show that all low risk ankle fractures can be safely treated in the same way as soft tissue injuries of the ankle. The current treatment of low risk fractures is casting which is inconvenient, necessitates orthopedic referral, and may be associated with soft tissue complications. Furthermore, casting is not an evidence-based practice. Preliminary evidence in adults with stable ankle fractures suggests that an ankle brace may offer a safe alternative to casting, while allowing comparable resumption of usual activities and less reliance on sub-specialty care. Therefore, the primary purpose of this study is to compare the functional outcomes that result from ankle bracing with those from casting in children with low-risk ankle fractures.

Design: In this randomized, outcomes assessor blinded, single center trial, children diagnosed with low-risk ankle fractures will receive either an ankle brace or a below-knee walking cast.

Outcome Measures: The primary outcome measure will be an assessment of functional daily activities as measured by the modified performance Activities Scale for Kids (ASKp) at four weeks post injury. Secondary outcomes will include an assessment of pain scores, ankle range of motion and return to baseline function. A concurrent health economic evaluation will be conducted using both patient and health care sector costs.

Sample Size and Analysis: The null hypothesis for the primary analysis is that the brace is less effective than casting by at least five percentage points on the ASKp scale. Assuming a standard deviation of 10%, alpha = 0.05, beta = 0.2 and 10% dropout rate yields a sample size of 112 patients. Secondary analyses will include Fisher's Exact test to compare proportions of children with full range of motion of the injured ankle at four weeks and with full baseline activity level at four months, and the area under the curve of a pain-time profile curve will be compared using a Student's t-test. An economic analysis will assess the incremental net benefit of bracing versus casting from a health care perspective.

Significance: If the removable brace is found to be at least as effective as the cast, this study has the potential to standardize the treatment of all low risk ankle injuries. Since these injuries can be reliably detected by physical examination, routine radiography of these injuries can be eliminated. These injuries could therefore be safely treated by primary physicians, thereby reducing the number of emergency department visits, obviating the need for orthopedic referral, or a return visit for cast removal. As a result, this study will provide critical information about the optimal treatment for the majority of ankle injuries in children from the perspective of clinical efficacy and health economics.