In the treatment of proximal humeral fractures (PHF), patients are often recommended to wear a sling or orthosis and to perform physiotherapy. However, some patients, especially elderly ones, struggle to comply with these rehabilitation regimens. Therefore, the aim of the study was to evaluate whether these incompliant patients have a worse functional outcome than those who adhere to the rehabilitation protocol. After receiving a diagnosis of a PHF, patients were divided into four groups according to fracture morphology: conservative with sling, operative with sling, conservative with abduction orthosis, and operative with abduction orthosis. At the 6-week follow-up, compliance regarding brace use and physiotherapy performance were assessed, as well as the constant score (CS) and complications or revision surgeries. The CS as well as the complications and revision surgeries were also surveyed after one year. In 149 participants, with a mean age of 73.9 ± 7.2 years, only 37% terminated orthosis and only 49% underwent physiotherapy as recommended. The statistical analysis showed no significant difference in the CS, complications, and revision surgeries between the groups.