A Prediction Model for Chronic Ankle Instability

Study Overview
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Brief Summary
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Chronic ankle instability is a common problem that may follow an ankle sprain. Until a patient has developed chronic ankle instability they are ineligible for surgical treatment although early surgical treatment yields better results compared to surgical treatment of subjects that have experienced recurrent ankle sprains. However, treating all patients with an ankle sprain surgically is not an option due to the high amount of unnecessary invasive interventions. The objective of this study is to identify which patients will develop chronic ankle instability and to develop a model to predict which patients should receive early surgical treatment. In this prospective observational cohort all patients (older than 18 years) that report at the emergency department of the participating hospitals after a lateral ankle sprain, of whom an x-ray is made after positive Ottawa Ankle Rules and on which there is no visible fracture or other pathology. The main study parameter is a significant difference in patient characteristics, foot and ankle configuration and joint pathology between patients who develop chronic ankle instability and patients who do not experience recurrent ankle sprains and restriction during daily live after an initial sprain.

Official Title
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A Prediction Model for Chronic Ankle Instability: Indications for Early Surgical Treatment? An Observational Prospective Cohort

Conditions
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Chronic Ankle Instability

Intervention / Treatment
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* Other: Patients do not undergo any type of interventions, but standard care if offered and accepted.


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: At least 16 years old Visited the ER within one week after a lateral ankle sprain An anteroposterior and lateral x-ray have been made Agreed with being approached for this study Questionnaires have been returned within 4 weeks Reported lateral ankle pain after an ankle sprain or ankle distortion ankle Exclusion Criteria: Present fracture or other joint pathology/bone matrix pathology A diagnosed osteochondral defect after primary inclusion Medial ankle instability Previous ankle surgery An unreliable x-ray due to the angle in which it is made or low quality Acute surgical repair of the anterior talofibular ligament and/or calcaneofibular ligament or another form of surgery within 6 months after the initial ankle sprain

Ages Eligible for Study
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Minimum Age: 16 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Patients with chronic ankle instability<br>All patients that develop chronic ankle instability after an ankle sprain and reporting at the emergency department. Experiencing persisting complaints of instability for more than 6 months. | Other: Patients do not undergo any type of interventions, but standard care if offered and accepted.<br> <br> |
| Patients without chronic ankle instability<br>All patients that do not develop chronic ankle instability after an ankle sprain and reporting at the emergency department. Complaints resolve within 6 months. | Other: Patients do not undergo any type of interventions, but standard care if offered and accepted.<br> <br> |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| The primary outcome measure is a prediction model based several factors. One of these is ankle joint alignment. | Ankle alignment is assessed as the medial distal tibial angle on a standard anteroposterior x-ray | 2 years anticipated | 
| The primary outcome measure is a prediction model based several factors. One of these is fibular position in relation to the tibia. | Position of the fibula is assessed on a lateral x-ray. | 2 years anticipated | 
| The primary outcome measure is a prediction model based several factors. One of these is the tibiotalar contact ratio. | The tibiotalar contact ratio is assessed as an angle originating from the center of the talus to the anterior and posterior edges of the distal tibia. | 2 years anticipated | 
| The primary outcome measure is a prediction model based several factors. One of these is sex. | Sex is registrated as male-female and has proven to be of prognostic value in previous research | 2 years anticipated | 
| The primary outcome measure is a prediction model based several factors. One of these is height. | Height is registrated in centimeters and has proven to be of prognostic value in previous research | 2 years anticipated | 
| The primary outcome measure is a prediction model based several factors. One of these is Body Mass Index (BMI). | BMI is registrated and has proven to be of prognostic value in previous research | 2 years anticipated | 
| The primary outcome measure is a prediction model based several factors. One of these is sports intensity. | Sports intensity is registrated using the ankle activity score taking type of sports into account and has proven to be of prognostic value in previous research. | 2 years anticipated | 
| The primary outcome measure is a prediction model based several factors. One of these is talar curvature. | The talar curvature is defined as the angle between the talar neck, most proximal talar part articulating with the tibia and the most distal part of the talus | 2 years anticipated | 
| The primary outcome measure is a prediction model based several factors. One of these is the height of the medial malleolus. | The medial malleolus is thought to restrict inversion motion, therefore the height is assessed using the angle between the tibiotalar joint and most distal part of the medial malleolus | 2 years anticipated | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Inter- and intrarater reliability of the prognostic factors assessed on ankle x-rays | Assessment of reliability of the bone geometric factors on anteroposterior and lateral x-rays | at about 6 months, when 40 patients are included | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Ankle, Instability, Prediction