Acute lateral ankle sprain to chronic ankle instability: a pathway of dysfunction.

Lateral ankle sprains (LAS) have been reported as one of the most common musculoskeletal injuries observed in sports and in individuals who are recreationally active. Approximately 40% of individuals who sustain a LAS develop a condition known as chronic ankle instability (CAI). Years of research has identified numerous impairments associated with CAI such as decreases in range of motion (ROM), strength, postural control, and altered movement patterns during functional activities when compared to individuals with no LAS history. As a result, an impairment-based rehabilitation model was developed to treat the common impairments associated with CAI. The impairment-based rehabilitation model has been shown to be an effective rehabilitation strategy at improving both clinical and patient-oriented outcomes in patients with CAI. To date, the efficacy of an impairment-based rehabilitation model has not been evaluated in patients with an acute LAS. Prior to implementing an impairment-based model for the treatment of an acute LAS, similarities between impairments associated with acute LAS and CAI across the spectrum of the healing process is warranted. Therefore, the purpose of this review paper is to compare and contrast impairments and treatment techniques in individuals with an acute LAS, sub-acute LAS, and CAI. A secondary purpose of this review is to provide clinical commentary on the management of acute LAS and speculate how the implementation of an impairment-based rehabilitation strategy for the treatment of acute LAS could minimize the development of CAI. The main findings of this review were that similar impairments (decreased ROM, strength, postural control, and functional activities) are observed in patients with acute LAS, sub-acute LAS, and CAI, suggesting that the impairments associated with CAI are a continuation from the original impairments developed during the initial LAS. Therefore, the use of an impairment-based model may be advantageous when treating patients with an acute LAS.