Functional deficits in chronic mechanical ankle instability

Abstract

Background: The interaction of functional and mechanical deficits in chronic ankle instability remains a major issue in current research. After an index sprain, some patients develop sufficient coping strategies, while others require mechanical support. This study aimed to analyze persisting functional deficits in mechanically unstable ankles requiring operative stabilization. Methods: We retrospectively analyzed the functional testing of 43 patients suffering from chronic, unilateral mechanical ankle instability (MAI) and in which long-term conservative treatment had failed. Manual testing and arthroscopy confirmed mechanical instability. The functional testing included balance test, gait analysis, and concentric-concentric, isokinetic strength measurements and was compared between the non-affected and the MAI ankles. Results: Plantarflexion, supination, and pronation strength was significantly reduced in MAI ankles. A sub-analysis of the strength measurement revealed that in non-MAI ankles, the peak pronation torque was reached earlier during pronation (maximum peak torque angle at 20°vs. 14°of supination, p < 0.001). Furthermore, active range of motion was reduced in dorsiflexion and supination. In balance testing, patients exhibited a significant increased perimeter for the injured ankle (p < 0.02). During gait analysis, we observed an increased external rotation in MAI (8.7 vs. 6.8°, p<0.02). Conclusions: This study assesses functional deficits existent in a well-defined population of patients suffering from chronic MAI. Impairments of postural sway, gait asymmetries, and asymmetric isokinetic strength can be observed despite long-term functional treatment. The finding that pronation strength is particularly reduced with the foot in a close-to-accident position indicates potential muscular dysfunction in MAI. Possibly, these deficits alongside the underlying mechanical instability characterize patients requiring mechanical stabilization.

Sprunggelenk-Instabilität: Wie unterscheide ich mechanisch von funktionell?

“…Isokinetic strength measurement also belongs to the portfolio of functional diagnostics for chronic upper ankle instability. As previously indicated with regard to gait, a deficit in the periarticular muscles have been observed with functional instability (and also with mechanical instability) [5,54]. The muscular deficits affect the isometric, eccentric, and concentric muscular activity of the pronators/supinators in different angular velocities, as shown in a current meta-analysis [54].…”

A test battery for evaluation of muscle strength, balance and functional performance in subjects with chronic ankle instability: a cross-sectional study

“…Regarding an acute trauma such as an ankle sprain, reduced strength is often noted in eversion and inversion [ 7 ]. Strength impairments have also been noted in chronic ankle instability patients [ 18 , 19 ]. The CAI subjects in the present study had reduced strength with a 20% difference in eversion and 16% in inversion between injured and non-injured ankle, but strength values did not differ compared to healthy subjects.…”

Limited medial osteochondral lesions of the talus associated with chronic ankle instability do not impact the results of endoscopic modified Broström ligament repair

“…It is more likely that OLTs of the medial portion of the talus are present in patients with long-standing CLAI [ 25 ] and rotational instability of the ankle [ 26 ]. In CLAI patients, internal–external rotation, anterior–posterior translation, and inversion in flexion increase: the medial side of the talus experiences greater sagittal plane motion within the mortise, resulting in increased shear forces and overload along this area [ 27 , 28 ]. Thus, OLTs on the medial talar dome are more commonly associated with CLAI as a result of rotational instability of the ankle [ 29 ].…”