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This Article Full Text Full Text (PDF) All Versions of this Article: 34/12/1970    most recent 0363546506290989v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Request Reprints Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Delahunt, E. Articles by Caulfield, B. Search for Related Content PubMed PubMed Citation Articles by Delahunt, E. Articles by Caulfield, B. Related Collections Kinematics and kinetics Ankle

Altered Neuromuscular Control and Ankle Joint Kinematics During Walking in Subjects With Functional Instability of the Ankle Joint

From the School of Physiotherapy and Performance Science, Health Sciences Centre, University College Dublin, Dublin, Republic of Ireland

^* Address correspondence to Eamonn Delahunt, BSc, School of Physiotherapy and Performance Science, Health Sciences Centre, University College Dublin, Belfield, Dublin 4, Republic of Ireland (e-mail: eamonn.delahunt{at}ucd.ie).

Background: The ankle joint requires very precise neuromuscular control during the transition from terminal swing to the early stance phase of the gait cycle. Altered ankle joint arthrokinematics and muscular activity have been cited as potential factors that may lead to an inversion sprain during the aforementioned time periods. However, to date, no study has investigated patterns of muscle activity and 3D joint kinematics simultaneously in a group of subjects with functional instability compared with a noninjured control group during these phases of the gait cycle.

Purpose: To compare the patterns of lower limb 3D joint kinematics and electromyographic activity during treadmill walking in a group of subjects with functional instability with those observed in a control group.

Study Design: Controlled laboratory study.

Methods: Three-dimensional angular velocities and displacements of the hip, knee, and ankle joints, as well as surface electromyography of the rectus femoris, peroneus longus, tibialis anterior, and soleus muscles, were recorded simultaneously while subjects walked on a treadmill at a velocity of 4 km/h.

Results: Before heel strike, subjects with functional instability exhibited a decrease in vertical foot-floor clearance (12.62 vs 22.84 mm; P < .05), as well as exhibiting a more inverted position of the ankle joint before, at, and immediately after heel strike (1.69°, 2.10°, and –0.09° vs –1.43°, –1.43°, and –2.78°, respectively [minus value = eversion]; P < .05) compared with controls. Subjects with functional instability were also observed to have an increase in peroneus longus integral electromyography during the post–heel strike time period (107.91%·millisecond vs 64.53%·millisecond; P < .01).

Conclusion: The altered kinematics observed in this study could explain the reason subjects with functional instability experience repeated episodes of ankle inversion injury in situations with only slight or no external provocation. It is hypothesized that the observed increase in peroneus longus activity may be the result of a change in preprogrammed feed-forward motor control.

Key Words: ankle sprain • electromyography (EMG) • gait analysis • motor control