Development of an effective diagnostic inventory for the valid assessment of functional ankle instability

Research objective: The lateral ankle sprain (LAS) is one of the most common injury in sports as well as in the general population and has a high risk of re-injury potentially leading to chronic problems. While impairment-based rehabilitation approaches for LAS are widely recommended, a fundamental challenge remains: the lack of standardized test inventories to objectively quantify mechanical and sensorimotor deficits in the acute phase of LAS. The aim of this thesis is to determine an effective diagnostic inventory for the valid measurement of a functional ankle instability. Specifically, the aim is to identify sensitive parameters that can differentiate between acutely injured LAS patients and a healthy control group. Ultimately, this study seeks to define cut-off values for an effective diagnostic inventory and develop a clinical implementation strategy to improve and guide rehabilitation following acute LAS. Methods: 2-3 weeks after first-time acute LAS, 36 injured and 36 uninjured participants performed a diagnostic comprising several test domains. This included psychometrics, postural control, strength, range of motion (ROM), proprioception, gait/ running, jumpperformance/ landing strategy. Independent t-tests for discrete parameters and statistical parametric mapping independent t-test for continuous parameters was performed. For each specific test domain, the significant parameter with the highest effect size was selected. Receiver operating characteristic curves with its according Youden-Index was used to estimate optimal cut-off values for the chosen parameters. Results: The recommended effective diagnostic inventory with its according cut-off values includes: - Psychometry – Foot and Ankle Ability Measure Sport (<86) & Cumberland Ankle Instability Tool (<26) - Postural Control – Star Excursion Balance Test Composite Score (<92.8) - Strength – concentric plantarflexion (<2.24 Nm/kg) - ROM – passive plantarflexion/ passive total ROM (<44°/ <72°) - Gait/ Running – Gait (transverse ankle kinematics) (<-15°) - Jump-Performance/ Landing-Strategy – Drop jump contact time (>0.23 sec) Conclusion: An implementation strategy could involve an initial screening of all acute LAS patients using the psychometric assessment within 2–3 weeks post-injury. If questionnaire scores fall below the established cut-off values, patients could be invited for a comprehensive assessment using the full diagnostic inventory, including postural control, strength, ROM, gait analysis, and jump performance. Based on these test results and the corresponding cut-off values, targeted rehabilitation recommendations could be provided to address specific impairments. This individualized rehabilitation strategy ensures a patient-centred approach, optimizing recovery and preventing long-term complications associated with LAS.