Does Prolonged Reconstruction of Disarticulation Defect With Bone Plate Affect the Electromyography Records of Masticatory Muscles?

OBJECTIVES: For medical or socioeconomic reasons, the primary reconstruction of disarticulation defects with bone plates stays for many years. This study was performed to assess the effect of this delay on electromyography (EMG) records of masticatory muscles. MATERIALS AND METHODS: Twenty-five patients treated by insertion of reconstruction plates in disarticulation defects were prospectively included in this study. Electromyography records for masticatory muscles were obtained before surgery and 3 months, 6 months, 1 year, 2 years, and 3 years afterward. Paired t-test was used to determine whether there was significant difference between the EMG values. RESULTS: At 3 years after surgery, the amplitude values of the masseter and temporalis muscles, on the resected side, have decreased by 39% and 60%, respectively, whereas on the nonoperated side, they have increased by 35% and 29%. The peak decrease, on the resected sides, has occurred at 3 months for the temporalis and 2 years for the masseter. On the nonoperated side, the peak increase has occurred at 6 months for both the temporalis and the masseter. CONCLUSIONS: A prolonged use of bone plates to reconstruct disarticulation defects leads to alterations in EMG values of masticatory muscles. These alterations present clinically as muscle atrophy on the operated side and hypertrophy on the nonoperated side.