The purpose of the project is to compare the management of 3 and 4 part proximal humerus fractures (PHF) with an angular stable plate (Philos) with that of an intramedullary nail (Multiloc) in light of complications, radiological, economical, functional and clinical outcome.

Randomized controlled trial (RCT) from Akershus University Hospital in Norway. Randomization between two implants. The investigators will use deltopectoral or deltoid split as surgical access. All patients will have calcar screws and cuff sutures. When lack of bone for example after decompressing valgus compressed fractures, a bone-substitute might be used in the surgeons preference. Follow up in outpatient clinic at 6, 12, 52 and 104 weeks, but also a 5 year follow up is planned. Postoperative radiographs of both shoulders and CT of operated shoulder will be taken.

Inclusion Criteria:

1. Patients > 18 years
2. Severe displacement, defined as malposition of at least 45⁰ of angular deviation in valgus or 30⁰ in varus in true frontal projection, regardless of whether the fracture is impacted or not. Fractures with more than 50% displacement of the head against the surgical neck
3. The greater or lesser tubercles must be fractured in a 3 or 4-part fracture. The degree of displacement is not critical for inclusion.

Exclusion Criteria:

Exclusion criteria:

1. Fracture more than 3 weeks' old
2. Caput humeri just a thin shell or split
3. Ipsilateral damage that will influence the recovery and scoring systems
4. Incapability to protect osteosynthesis, i.e. use of crutches because of injury to lower extremity.
5. Pathological fracture
6. Neurovascular injury
7. Open fracture
8. Noncompliance
9. Congenital anomaly
10. Ongoing infectious process around the incision site for plate osteosynthesis
11. Systemic disease that may influence healing processes or scoring systems (RA/MS)
12. Fracture dislocation
13. Substance abuse
14. Inability to read and understand Norwegian
15. Patients not residing in our catchment area
16. Patients with too small humerus diameter to use a nail
17. Patient not able to commit and understand written consent

De-identified individual participant data for all primary and secondary outcome measures will be made available within 6 months of study completion