Subgroup characteristics of patients with chronic ankle instability in primary care

Objectives To examine clinical and radiological characteristics of participants with an ankle sprain in general practice, classified into subgroups of a previously described chronic ankle instability (CAI) model. Design Cross-sectional study. Methods 206 participants, who visited their general practitioner with a lateral ankle sprain 6–12 months before inclusion, completed a questionnaire, physical examination, radiography and magnetic resonance imaging. They were classified into three subgroups of the previously described CAI-model: mechanical instability (MI), perceived instability (PI) and recurrent sprains (RS). Regression analyses were applied to evaluate differences in subgroup characteristics. Results A total of 192 participants were eligible to be classified into the model. Of these participants, 153 participants were classified into the subgroups and 39 could not be classified. With overlap between the subgroups and patients falling into more than one subgroup, 59 were classified having MI, 145 having PI and 30 having RS. Participants with RS and PI were more often sports participants (OR 6.83;95%CI 1.35–34.56 and OR 4.44;95%CI1.06–18.63 respectively) than participants without RS and PI. Participants with MI more often had a tenderness on palpation of the anterior talofibular ligament (OR 4.09;95%CI 1.91–8.72) and a KL-score ≥ 1 in the talonavicular joint on X-ray (OR 2.24;95%CI 1.09–4.58), compared to participants without MI. Conclusions Sports participation, tenderness on palpation of the anterior talofibular ligament and early signs of osteoarthritis were variables that discriminated between subgroups of CAI. However, further research is mandatory in order to examine the usefulness of the CAI model in relation to prognosis and suitable intervention.