Effect of Axon Misdirection on Recovery of Electromyographic Activity and Kinematics after Peripheral Nerve Injury

In this study, patterns of activity in the soleus (Sol) and tibialis anterior (TA) muscles and hindlimb kinematics were evaluated during slope walking in rats after transection and surgical repair either of the entire sciatic nerve (Sci group) or of its two branches separately, the tibial and common fibular nerves (T/CF group). With the latter method, axons from the tibial and common fibular nerves could not reinnervate targets of the other nerve branch after injury, reducing the opportunity for misdirection. Activity in the TA shifted from the swing phase in intact rats to nearly the entire step cycle in both injured groups. Since these changes occur without misdirection of regenerating axons, they are interpreted as centrally generated. Sol activity was changed from reciprocal to that of TA in intact rats to coactivate with TA, but only in the Sci group rats. In the T/CF group rats, Sol activity was not altered from that observed in intact rats. Despite effects of injury that limited foot movements, hindlimb kinematics were conserved during downslope walking in both injury groups and during level walking in the T/CF group. During level walking in the Sci group and during upslope walking in both groups of injured rats, the ability to compensate for the Published online: March 17, 2011 Dr. Manning J. Sabatier Department of Natural Sciences, Health and Fitness Management Clayton State University 2000 Clayton State Blvd, Morrow, GA 30260 (USA) Tel. +1 678 466 4619, Fax +1 678 466 4669, E-Mail ManningSabatier @ clayton.edu © 2011 S. Karger AG, Basel Accessible online at: www.karger.com/cto Abbreviations used in this paper EMG electromyographic MTP metatarsophalangeal PC principal component PCA principal components analysis Sci group sciatic nerve group Sol soleus TA tibialis anterior T/CF group tibial and common fibular nerves group D ow nl oa de d by : 54 .7 0. 40 .1 1 11 /5 /2 01 7 7: 13 :0 0 P M