Effects of lidocaine into knee on QF strength and EMG in patients with ACL lesion.
OBJECTIVE
In our previous study, we found that injection of lidocaine into intact knees reduced the maximal voluntary contraction (MVC) and integrated electromyogram (I-EMG) of the quadriceps femoris (QF). This study was designed to investigate changes in the MVC and I-EMG of the QF in response to lidocaine, in patients with anterior cruciate ligament (ACL) lesion, to evaluate alpha-motoneuron activity innervating the QF.


METHODS
The MVC of knee extension and I-EMG of the vastus medialis (VM), vastus lateralis (VL), and rectus femoris (RF) muscles were measured in eight patients with ruptured ACL, before and after lidocaine injection into the knee.


RESULTS
There were no significant differences between preinjection and postinjection values of MVC (preinjection: 167 +/- 49 N.m; postinjection: 164 +/- 55 N.m) and I-EMG (preinjection: VL: 0.11 +/- 0.06, VM: 0.13 +/- 0.10, RF: 0.09 +/- 0.04) (postinjection: VL: 0.12 +/- 0.07, VM: 0.13 +/- 0.10, RF: 0.09 +/- 0.05).


CONCLUSIONS
Our results indicated that hindrance of afferent feedback from the knee in patients with ACL rupture did not significantly change alpha-motoneuron activity. Lidocaine injection into the knee joint of the subjects in this study only attenuated afferent feedback from mechanoreceptors in the knee joint cavity, but not in the ACL, as afferent feedback from ACL was already lost due to ACL rupture. This indicated that attenuation of afferent feedback from mechanoreceptors in the knee joint cavity other than the ACL did not significantly decrease the activity of alpha-motoneurons innervating the QF during MVC exertion. Therefore, our findings provide evidence that afferent feedback from the ACL has a major influence on the MVC exertion of the QF.
Department of Life Sciences, Graduate School of Arts and Science, University of Tokyo, Tokyo, Japan. yuk1@fb.freeserve.ne.jp
Yu
Y
Konishi
Yuji
Y
Suzuki
Norikazu
N
Hirose
Toru
T
Fukubayashi
D000293:Adolescent; D000328:Adult; D016118:Anterior Cruciate Ligament / Q000187:drug effects / Q000503:physiopathology; D000070598:Anterior Cruciate Ligament Injuries; D004576:Electromyography; D005246:Feedback / Q000502:physiology; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000187:drug effects* / Q000503:physiopathology; D008012:Lidocaine / Q000008:administration & dosage; D008297:Male; D009046:Motor Neurons / Q000502:physiology; D009119:Muscle Contraction / Q000502:physiology; D018482:Muscle, Skeletal / Q000187:drug effects* / Q000294:innervation / Q000503:physiopathology
D008012:Lidocaine