Article

In 15 patients the EMG of the glutaeus medius muscle and of different muscles of the thigh and the shank was investigated by a standard program pre- and postoperatively. The following operations were performed : tenotomy or transposition of abductors, tenotomy or transposition of kneeflexors, achillotenotomy. In most of the patients more than one operation were done simultaneously. In 12 patients the EMG was investigated on two different times without an operation between them. Furtheron the results of these investigations were compared with the results of earlier (already published) investigations of 113 cerebral palsied patients and 45 healthy probands. The electromyographic variables of the different groups were compared by the STUDENT-test. In addition, a classification of the pecularities of the EMG was done by discriminant analysis taking in consideration the most characteristics signs of the EMG. The results show that all signs concerning the pattern of coordination of the pre- and postoperative muscular activities do not show any distinct differences. Moreover the comparison of the pre- and postoperative EMG shows that they are often similar also in details. Differences are only seen in the relation of the magnitude of activities of the muscles. These changes are expression of the normalization of the relation of agonists and antagonists. They can be explained by a change of the mechanical premisses. Planning myoplastic operations one must keep in mind the possibility that the timing of muscle activity will not be influenced by the operation and that the success of the operation is caused by an improvement of the biomechanical premisses alone without change of the pattern of muscle innervation. The comparison of pre- and postoperative electromyograms is described in many papers (1, 2, 3, 4, 5, 6, 8, 9, 10, 11, 13, 14). The question was whether the results of operations can be predicted by electromyography (EMG) or not. Furtheron the investigation should inform about the effectivity of the operation. Were are interested in the influence of the following factors : 1. Is the reflectory activity of the muscles influenced by changes of the tension during operations ? 2. Does the pattern of muscle activity show reaction upon the changed mechanical conditions of work ? 3. Is the result of myoplastic operations only due to the improvement of the mechanical conditions of work ? The results of the pre- and postoperative electromyographical investigations published by other authors are different. Partial changes in muscle activity are described corresponding to the results of the operation. On the first place accomodations of the extent of activity to the mechanical requirement according to clinical observations are seen. The result of operations is a normalisation of the pattern of activity e.g. Stotz (1979). More over it was assumed that the better is the timing of activity before operation the better is the prognosis of the operations e.g. Sutherland et al. (1969). But it happened that there were often found no changes of the activity of the muscles after the operation.
The question if there is an important correlation between the change of the conditions of mechanical work and the change of muscular activity is answered in different ways. In most papers it is stated that the effect of the operation on the pattern of activity shown by the EMG is variable. A special difficulty results in the fact that in most cases several muscles are operated simultaneously.
This paper deals mainly with the question if myoplastic operations result in a changing of performance of the coordination of muscle activity and if the quality of the preoperative coordination of muscle activity and if the qualify of the preoperative coordination correlates with the success of the operation.

Langue : ANGLAIS

Identifiant basis : 1985002388