The outcome of shoulder replacement for trauma has been studied in large series but not always all factors have been examined for their effects on the final results. One important element not sufficiently considered regards neurological impairment. This complication is reported in 1%–67% of shoulder dislocations and humeral neck fractures. Electromyography has an important role in revealing nerve injuries undetected by clinical examination alone. Three patients with typical neurological impairment complicating proximal humeral fractures are reported. The cases were studied through clinical, radiographical and electromyographical examinations, before and after undergoing shoulder hemiarthroplasty. Only a few reports have described nerve lesions in hemiarthroplasty for proximal humeral fractures, we discuss these typical cases and review the recent literature on the topic.