Arthrogenic muscle inhibition is not present in the limb contralateral to a simulated knee joint effusion.
OBJECTIVE
The purpose of this investigation was to estimate bilateral neuromuscular activity in the vastus medialis on induction of a unilateral knee joint effusion.


METHODS
Eight subjects each were assigned to effusion or control groups. The effusion group had 60 ml of sterile saline injected into their superolateral knee joint capsules. The control group rested for 8 mins. Bilateral recruitment curves for the Hoffmann reflex (H-reflex) and muscle response (M-wave) were obtained before and 10, 20, and 30 mins after the effusion or rest. The maximum H-reflex (Hmax), maximum M-wave (Mmax), and the Hmax/Mmax ratio were utilized for data analysis.


RESULTS
Both Hmax and Hmax/Mmax ratios decreased from the baseline measure in the effused vastus medialis, whereas no changes were detected on the contralateral side. Effused subjects demonstrated decreased motoneuron pool excitability in the effused limb, whereas control subjects did not differ from baseline.


CONCLUSIONS
Knee joint effusion results in ipsilateral but not contralateral impairment of quadriceps function. Rehabilitation protocols after knee joint injury should focus on ipsilateral neuromuscular and mechanical alterations that occur as the result of joint damage.
Palmieri
Riann M
RM
Department of Human Services, University of Virginia, Charlottesville 22904-4407, USA.
Ingersoll
Christopher D
CD
Edwards
Jeffrey E
JE
Hoffman
Mark A
MA
Stone
Marcus B
MB
Babington
J Patrick
JP
Cordova
Mitchell L
ML
Krause
B Andrew
BA
D000328:Adult; D006181:H-Reflex / Q000502:physiology*; D006801:Humans; D007718:Knee Injuries / Q000503:physiopathology*; D007719:Knee Joint / Q000473:pathology*; D009046:Motor Neurons / Q000502:physiology; D018482:Muscle, Skeletal / Q000502:physiology*; D011999:Recruitment, Neurophysiological / Q000502:physiology