[Morphologic basis for electric stimulation therapy of the vastus medialis and vastus lateralis muscles]

Based on knowledge of the pattern of motorend plates in the m. vastus medialis (VM) and lateralis (VL), the author investigated the electrically most excitable sites which can be used in standard procedures of transcutaneous electric stimulation in muscular hypotrophy. The investigation was made in 21 patients, most of them after a reconstruction of the anterior cruciate ligament and one healthy adult. For stimulation and recording of potentials the EMG device Neuromatic 2000 C (Dantec, Scovlunde, Denmark) was used. First by means of a needle electrode the zone of motorend plates was verified. Then the minimal intensities causing muscular contraction and equal amplitude were compared during stimulation of the zone of motorend plates and 2.5 proximal and distal from the zone. The potentials were recorded by means of surface electrodes from distal portions of the muscle bellies. In five patients automatic RTI 50 analysis according to Brismar was used as well as monopolar stimulation where the cathode was placed at different sites above the muscle belly and the anode above the proximal margin of the muscle. The results of evaluation of minimal stimulation intensities of both muscles revealed significantly lowest values during stimulation of the zone of motorend plates (mean VM 8.5 mA, VL 9.9 mA) followed by intensities on stimulation proximally from the zone (VM 18.2 mA, VL 17.5 mA) and the highest intensities were recorded on stimulation of the distal part of the muscle (VM 21.2 mA, VL 25.8 mA). Similarly the results of RTI 50 analysis and monopolar stimulation provide evidence of maximal excitability in the area of the motorend plate zone.(ABSTRACT TRUNCATED AT 250 WORDS)