[Translated article] Electromyographic axillary nerve injury in fractures of the proximal humerus: Prospective, observational study, analysing the fracture pattern.

OBJECTIVE: Description and analysis of the relation between the proximal humerus fracture patterns and the traumatic injury of the axillary nerve. MATERIAL AND METHOD: Prospective, observational study of a consecutive case series that analysed proximal humerus fractures. Radiographic evaluation was performed, and AO (Arbeitsgemeinshaft für Osteosynsthesefragen) system was used to classify the fractures. Electromyography was used to diagnose the axillary nerve injury. RESULTS: Thirty-one patients on 105 who had a proximal humerus fracture met inclusion criteria. Eighty-six percent of the patients included were women and 14% men. The mean age was 71.8 years (30-96 years). Of the patients included in the study, 58% had normal or mild axonotmesis EMG, 23% had axillary nerve neuropathy without muscle denervation and 19% had injury with axillary nerve denervation. Patients who suffered complex fractures of the proximal humerus (AO11B and AO11C) had a higher risk of presenting axillary neuropathy type lesions with muscle denervation in the EMG, this relationship being statistically significant (p<0.001). CONCLUSION: Patients who have more risk on presenting axillary nerve neuropathy with muscle denervation in electromyography are those who present complex proximal humerus fractures AO11B and AO11C (p<0.001).