Effects of ankle joint effusion on lower leg function.
BACKGROUND
Inversion ankle sprains are among the most frequently encountered injuries in and outside of sport. Altered feedback from joint damage and/or edema may negatively affect dynamic stabilization, thereby increasing the patients' susceptibility to further injury. In order to understand better how the sensorimotor system responds to the presence of ankle edema during a functional task, further examination is warranted.


OBJECTIVE
To quantify muscle activation in the peroneal, tibialis anterior, and soleus musculature as well as to determine ankle joint peak torque, peak power, and root mean square (RMS) power during a closed kinetic chain activity following artificial ankle effusion.


METHODS
Dependent variables were compared within subjects across time intervals and between groups.


METHODS
All data were collected in the biomechanics laboratory.


METHODS
Subjects were 20 healthy, neurologically sound volunteers (age 21.9 +/- 2.1 y, height 174.5 +/- 9.3 cm, mass 79.3 +/- 15.9 kg) with no lower extremity injuries.


METHODS
Subjects were prepared for surface electrodes on the peroneus longus (PL), tibialis anterior (TA), soleus (Sol), and medial malleolus (ground). Anthropometric measures for the lower extremity were recorded for use by the Omnikinetic closed chain dynamometer. Measurements were taken prior to ankle effusion (baseline), immediately following effusion (post), and again at 30 minutes.


METHODS
Testing consisted of 6 repetitions at 35% of 1-repetition max and a constant speed of 1.5 Hz. Separate two-way MANOVAs with repeated measures on time intervals were used to detect differences between groups (effusion and control) over time for torque, power, and RMS power and for peak and average EMG.


RESULTS
An overall time x group interaction was detected for EMG (F4,72=3.878; P=0.007) and kinetic variables (F6,70=5.55; P=0.0001). Average and peak PL EMG decreased immediately following effusion (Sidak's; P=0.048), and average EMG remained depressed 30 minutes following effusion (Sidak's; P=0.02). Immediately posteffusion, a decrease in ankle torque was detected (Sidak's; P=0.007). No differences in TA or Sol EMG, power, or RMS power were detected (P>0.05).


CONCLUSIONS
Decreases in ankle plantarflexion torque and PL EMG indicate that a neuromuscular deficit exists in the presence of edema that could increase the susceptibility for further ankle injury.
Hopkins
J Ty
JT
Department of Physical Education, Brigham Young University, Provo, UT 84602-2070, USA. tyhopkins@byu.edu
Palmieri
Riann
R
D000328:Adult; D000843:Ankle Joint / Q000503:physiopathology*; D001696:Biomechanical Phenomena; D004576:Electromyography; D005122:Exudates and Transudates; D005260:Female; D006801:Humans; D007592:Joint Diseases / Q000139:chemically induced / Q000503:physiopathology*; D007866:Leg / Q000503:physiopathology; D008012:Lidocaine; D008297:Male; D008954:Models, Biological; D018482:Muscle, Skeletal / Q000503:physiopathology*; D009469:Neuromuscular Junction / Q000503:physiopathology
D008012:Lidocaine