Individuals with both perceived ankle instability and mechanical laxity demonstrate dynamic postural stability deficits.
BACKGROUND
Chronic ankle instability is a frequent and serious consequence of lateral ankle sprains. The contribution of perceived instability and potential for mechanical laxity to contribute to the overall deficit in dynamic postural stability is unclear. The purpose was to determine if those with mechanical laxity demonstrated significant differences in dynamic postural stability compared to controls, copers and those with perceived instability.


METHODS
Of 93 participants, 83 recreationally active individuals were divided into 4 groups: controls, copers, those with perceived instability, and those with both perceived instability and mechanical laxity. Injury history and the Cumberland Ankle Instability Tool were collected, and an instrumented arthrometer was applied. Participants completed a single limb jump landing, balancing upon completion. Ground reaction force data were collected, scaled to body mass, and the Dynamic Postural Stability Indices were calculated for anterior-posterior, medial-lateral, vertical and composite. One-way ANOVAs with Tukey post-hoc tests (α<0.05) were conducted on each of the stability indices among the four groups.


RESULTS
The mechanically lax group had significantly greater mean (standard deviation) medial-lateral stability index scores 0.57 (0.62) than the coper group 0.24 (0.20; P=0.02) and significantly greater composite index scores 0.73 (0.57) than the perceived instability 0.49 (0.09) and coper groups 0.47 (0.12 P=0.05). No other indices were significantly different among groups.


CONCLUSIONS
Individuals with perceived instability and mechanical laxity exhibited dynamic postural deficits compared to copers and those with perceived instability alone. Mechanical laxity may contribute to the deficits in dynamic postural stability.
Biomechanics Laboratory, Department of Kinesiology, University of Georgia, 330 River Rd, Athens, GA 30602, USA. Electronic address: browncn@uga.edu.
Cathleen N
CN
Brown
Biomechanics Laboratory, Department of Kinesiology, University of Georgia, 330 River Rd, Athens, GA 30602, USA. Electronic address: jpko@uga.edu.
Jupil
J
Ko
School of Health, Physical Education and Recreation, University of Nebraska at Omaha, HPER Building 207Y, Omaha, NE 68182-0216, USA. Electronic address: arosen@unomaha.edu.
Adam B
AB
Rosen
Biomechanics Laboratory, Department of Kinesiology, University of Georgia, 330 River Rd, Athens, GA 30602, USA. Electronic address: khsieh7@uga.edu.
Katherine
K
Hsieh
D000328:Adult; D000704:Analysis of Variance; D016512:Ankle Injuries / Q000503:physiopathology*; D000843:Ankle Joint / Q000503:physiopathology*; D001696:Biomechanical Phenomena; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D007593:Joint Instability / Q000503:physiopathology*; D008297:Male; D004856:Postural Balance / Q000502:physiology*; D013180:Sprains and Strains / Q000503:physiopathology*; D055815:Young Adult
Arthrometry; Chronic ankle instability; Talar tilt