Surgical Versus Non-surgical Treatment of Displaced Proximal Humerus Fracture in Adults Aged 50 to 65 Years

The goal of this clinical trial is to study whether surgery results in better functional outcomes than non-surgical treatment among patients aged 50-65 with a displaced proximal humerus fracture.

The main questions it aims to answer are:

• Does osteosynthesis result in better patient-reported functional outcomes compared to non-surgical treatment at 12 months follow-up?

Aim is also to characterize the patient group aged 50-65 regarding fracture morphology, osteoporosis, and clinical frailty scale.

The study compare operation with either plate or nail fixation to non-surgical treatment.

Participants will:

* Receive either surgical treatment or non-surgical treatment.
* At 6 months, 1 year, and 2 years, the patient will answer two short questionnaires (Oxford Shoulder Score and Eq-5D-3L).

The primary outcome will be Oxford Shoulder Score at 12 months. The secondary outcome will be OSS at 6 and 24 months and EQ-5D-3L score measured at the same time-points. Adverse events and conversion to surgery will be registered. OSS and EQ-5D-3L will be completed just before the 6 months visit.

Proximal humerus fractures (PHF) are common injuries. At the age of 60 and above, no clinically important difference between surgical and non-surgical treatment after one year has been reported based on a recent Cochrane review of 10 trials.

The treatment of choice for displaced PHF in adults 50-65 years is anatomical reconstruction, and osteosynthesis if possible, which is why many patients in this age group with a displaced PHF undergo surgical treatment.

Orthopaedic surgeons may encounter challenges in guiding patients and formulating treatment strategies within specific age groups due to the absence of inclusion of this younger patient demographic in existing evidence. Knowledge is primarily derived from studies on the population aged 60 years and above. There exists an intermediate age group of patients for whom it remains uncertain whether the benefits and harms of non-surgical and surgical interventions are comparable

This trial is a two-center, parallel-group, randomized, superiority trial comparing osteosynthesis with non-surgical treatment following a displaced proximal humerus fractures in patients aged 50-65 years. The participants will be included and allocated equally to surgical treatment with osteosynthesis (comparator) with non-surgical treatment (intervention).

The surgical group will visit the outpatient clinic after 2, 12, and 24 weeks, while the non-surgical group will visit after 6, (12) and 24 weeks. X-rays will be obtained before every visit.

Both groups will be referred to rehabilitation in the municipalities.

Without a patient-derived MCID for PHF, a relevant difference of 9,6 was assumed to represent clinically meaningful difference. This is equivalent to approximately a 20 % difference between the surgical group and the non-surgical group on a 0-48 OSS scale. With a power of 80% and a 5% level of significance, a sample size of 25 participants per group is required. Assuming a 15 % loss to follow-up, the recruitment target is 30 patients in each group, meaning 60 participants overall.

In case of treatment failure in either group, defined as persistent pain or a failed osteosynthesis, a salvage procedure with secondary osteosynthesis or a reverse shoulder arthroplasty (RSA), will be offered.

Additionally, there are plans for a systematic collection of reasons for non-inclusion of eligible patients who were not recruited into the trial (decliner cohort), and their baseline characteristics, treatment preferences. The decliner cohort will receive the same treatment, follow-up, and outcome measurements as the included patients.

Statistical analysis:

For the primary outcome, a two-sample t-test will be used. P-value \< 0.05. For secondary outcome - considering the hierarchical nature of the data - clustered and repeated measure data - linear mixed models will be utilized for the statistical analysis.

Salvage procedures and adverse events will be reported descriptively. Reoperation in the form of amotio will be considered a complication and, therefore, not included in the statistics of salvage procedures. The time of salvage procedures in both groups will be recorded and analysed using the Cox proportional hazard model

As suggested in the extension of the CONSORT 2010 statement, the primary endpoints will be analysed for the intention-to-treat (ITT) population and, for sensitivity reasons, for the per-protocol (PP) population. There will be two analyses for both ITT and PP populations: one including salvage procedures and one excluding them. These analyses will be used to evaluate the occurrence of salvage procedures and the intervention's effect.

The length of rehabilitation will be presented with a mean and standard division for each of the groups. Differences in adherence to rehabilitation within the groups will be reported using the chi-squared test. Linear mixed models will be employed to test whether adherence to rehabilitation modifies the effect of the groups.

All statistical analyses will also be conducted for the decliner cohort, including a comparison of the primary outcome between those with a preference for surgical treatment and those with a preference for non-surgical treatment

Eligibility Criteria:
Inclusion Criteria:

* Patients aged between 50 and 65 years with a displaced PHF assessed to be constructible by the treating surgeon after a low-energy trauma will be considered for eligibility.
* Patients should be cognitively capable of answering the follow-up questionnaires.

Exclusion Criteria:

* The patient does not understand written and spoken native language (Danish or Finnish/Swedish)
* Inability to give informed consent
* Fractures assessed to be unreconstructedly by the treating surgeon
* Isolated tuberosity fracture, fracture dislocations, open fractures, and fractures with involvement of the articular surface
* Less than 25% contact between head fragment and metaphysis/diaphysis measured at two perpendicular radiographs at two weeks.
* Pathological fractures or previous fractures in the same proximal humerus
* Concomitant fractures, which could influence the outcome
* Paralysis in upper extremity