Relationship between mechanical ankle joint laxity and subjective function.

BACKGROUND: An increase in ankle joint laxity has been reported in patients with chronic ankle instability (CAI). However, it is not known if this increase in joint laxity is responsible for the subjective level of functional deficits also reported in these patients.
METHODS: One hundred twenty subjects with unilateral CAI (55 males, 65 females; age, 20.6 ± 1.5 years; mass, 74.5 ± 13.6 kg; height, 174.2 ± 9.7 cm) participated in the study. Mechanical joint stability was measured with an instrumented ankle arthrometer. The arthrometer measured ankle joint motion for anterior/posterior translation and inversion/eversion angular displacement. Subjective level of function was assessed with the foot and ankle disability index (FADI) and foot and ankle disability index sport (FADIS). Bivariate correlations using Pearson Product Moments were made between all dependent variables taken on the unstable ankles.
RESULTS: The strongest relationship was between anterior laxity and the FADIS (r = -0.88, p < 0.0001). As scores on the FADIS decreased, anterior laxity increased. Similar significant results were reported for anterior laxity and the FADI (r = -0.65, p = 0.013), as well as inversion laxity and the FADI (r = -0.53, p = 0.017) and FADIS (r = -0.45, p = 0.013).
CONCLUSION: These data demonstrate that there appears to be a relationship between anterior and inversion ankle laxity and subjective function in those with CAI. Although numerous insufficiencies develop after an ankle sprain, increased laxity may cause some of the subjective functional deficits reported in those with CAI. CLINICAL RELEVANCE: Strategies to prevent increased laxity following ankle sprain may improve the patient's subjective level of function.