The optimal treatment of complex shoulder fracture is controversial. In general, non-surgical treatment is recommended for older patients, but results are often unsatisfying. Therefore different surgical approaches have been tried to improve outcomes for this group of patients. Reverse shoulder arthroplasty has shown promising results for these types of fractures and changes in the design of the implant might improve outcomes further. The aim of this study is to compare the outcomes of complex shoulder fractures after non-surgical versus surgical treatment and compare two different types of implants.

The optimal treatment of proximal humeral fracture (PHF) Neer type III and IV AO B1.1,1.2 and C1.1,3.1 is controversial. National guidelines for Denmark have been published in 2015 and updated 2019. They recommend conservative treatment to all kinds of PHF for patients aged above 60 years. Exceptions are fracture-dislocations, headsplits or surgical conditions, where intervention is mandatory like open fractures and impaired nerve- and circulation.

Recently reverse shoulder arthroplasty (RSA) has gained expanding popularity in treating PHF . Compared with osteosynthesis (ORIF) or hemiarthroplasty (HA) outcomes were superior , . The importance of tuberosity healing for good functional outcomes has lead to development of different implants and fixation techniques. The original RSA design by Grammont with 155 degree inclination of the humeral stem was made for cuff-arthropathy. This design moves the center of rotation in a medial direction, and increase the tension on the tuberosities.

In contrast "anatomical" designed humeral implants with 135 degree enables more anatomical refixation of the tuberosities with less tension and might reduce the risk of resorption or displacement of the fragments. To implant a 155 degree RSA the surgeon has to remove parts of the rotator cuff, to enable the sliding rotation. On the other hand with a 135 degree inclination humeral component, a cuff sparing technique is possible.

The aim of this study is to compare outcomes of two different designed RSA stems versus conservative treatment of PHF Neer type III or IV / AO B&C.

Inclusion Criteria:

Displaced Proximal Humeral Fractures (PHF) Neer type III or IV / AO B&C. Radiological confirmed

Exclusion Criteria:

other types of PHF, Head splits, gleno-humeral dislocations, pathological fractures. Refuse to participate in the study. Non-compliant, drug/alcohol abuse or institutionalized, (Low-cooperative),

non information of the type of implant used is given to the patient