Although physical factors play an important role in the treatment and outcomes after proximal humerus fracture (PHF), psychosocial factors need to be taken into account as well.

Few studies have been done to assess the influence of psychosocial factors and mental distress on the outcomes after shoulder surgery and show that it has a negative correlation on the outcomes. It is reported that having low resilience, negative thoughts, signs of depression or anxiety have a significant negative relation with the patient reported outcomes (PROMs).

Mental vulnerability is linked to neuroticism, a personality factor of the Big Five traits, that can be characterized by the tendency to experience negative affect, especially when threatened, frustrated, or facing loss. Neuroticism is related to worse outcomes of health and disease in patients. Although studies have been done to objectify the correlation between psychological factors and functional outcomes after surgery there has not yet been a trial where an intervention has taken place to improve functional outcomes when patients have neurotic tendencies. With this study, we aim to improve the functional outcomes for patients with neuroticism and proximal humerus fractures undergoing surgery by giving them psychological training in the form of focused cognitive behavioral therapy additionally to the standard care. Psychological treatment has shown to improve the well-being of the 'patient characteristics associated with neuroticism and reduce rumination and worry.

Therefore, we hypothesize that providing psychological guidance, consisting of a focused cognitive behavioral therapy program, to patients with neuroticism after a PHF will lead to better patient related outcomes.

Introduction The primary objective of this study is to investigate whether psychological guidance, additionally to the standard care, given to patients with neuroticism that sustained a proximal humerus fracture, influences functional outcomes. The secondary objectives are to study if psychological guidance will lead to a better range of motion, lower pain levels, less use of pain medication, faster return to work, improvement in fear for movement, anxiety, depression, acceptance, self-efficacy, resilience, negative pain cognitions and better general health.

Methods This study is designed as a multicenter, prospective randomized controlled trial. Due to the nature of this study, it will be a single blinded study, the researchers will be blinded.

All patients with a PHF will be given information about the study via their physician and if they are eligible they are provided with the patient information form. The physician will notify the researcher and the researcher will call the patients to give more information about the study if needed and will ask for consent. Following consent neuroticism will be tested via the NEO-FFI. If patients score average or (very) low on neuroticism the patients will be thanked for filling in the questionnaire and will be told they are not eligible for the study. If patients score (very) high on neuroticism the researcher will ask the patient to participate. The researcher will give the patient up to seven days to consider participating in the study. After this period, the researcher will contact the patient again to obtain informed consent. If consent is given, another researcher will later randomize the patient into either the control group or the treatment group.

Intervention The control group will undergo the standard postoperative care consisting of multiple outpatient clinic visits with their surgeon where they will make additional radiographic pictures if needed and will look for early complications. Besides the visits with their surgeon the patients will have visits at 3, 6 and 12 months with a researcher or their surgeon. Besides the visits all the patients will be referred to a physical therapist. The intervention group will undergo the standard postoperative care and will additionally get psychological guidance given by licensed psychologists. The psychological guidance will consist of eight sessions over a duration of six months and starts two to three weeks after surgery.

Randomization and blinding When the patient provides informed consent, they will be randomly assigned (1:1) to the intervention (psychological training) group or the control group (standard follow up) using a web-based application with a computer-generated list. Participants are aware of allocation; masking is impossible because of the nature of the intervention. Investigators doing the follow up appointments are not aware of allocation. The investigator who will randomize the participants will be aware of allocation but will not take part in obtaining the data or the analysis of the data. We will employ an intention to treat analysis.

Sample size calculation Our sample size calculation was based on the CSS, as that is the most objective scoring system out of the OSS, CSS and qDASH, and a review, written by Buchbinder et al.l, on the different tools to measure shoulder function. They found a standard deviation of 17 and a minimally important change of 12 to detect a relevant difference between groups. With an alpha of 5% and power of 80%, 32 patients were needed per group. Taking into account an expected 10% loss of to follow up, inclusion of 35 patient per group was calculated and thus the aim was to include 70 patients in the total study.

Adverse events The sponsor will suspend the study if there is sufficient ground that continuation of the study will jeopardise subject health or safety. The sponsor will notify the accredited METC without undue delay of a temporary halt including the reason for such an action. The study will be suspended pending a further positive decision by the accredited METC. The investigator will take care that all subjects are kept informed.

(Serious) adverse events will be recorded from the start of the study until the end of the follow up period. If a life-threatening SAE is encountered, this study will be stopped immediately. The safety committee is then asked to perform and report an analysis of this SAE before the study will continue. The investigator will report all SAEs to the sponsor without undue delay after obtaining knowledge of the events, except for the following SAEs. The sponsor will report the SAEs through the web portal ToetsingOnline to the accredited METC that approved the protocol, within 7 days of first knowledge for SAEs that result in death or are life threatening followed by a period of maximum of 8 days to complete the initial preliminary report. All other SAEs will be reported within a period of maximum 15 days after the sponsor has first knowledge of the serious adverse events.

Statistical analysis The research data will be analysed using SPSS. A two sided p-value <0.05 indicates statistical significance. Differences between treatment groups will be assessed. The CSS, the VAS scores, rehabilitation time, time away from work, time not participating in normal daily activities, ROM, OSS and qDASH are continuous variables and will be presented as mean with SD (parametric) or median with quartiles (non-parametric) and compared using the Student's T-test (parametric) or Mann-Whitney U-test (non-parametric) according to the distribution of the data. The distribution of continuous data will be assessed visually inspecting histograms and boxplots. The MCID for the outcome measure will be used to determine the clinical relevance of the observed differences. To include all consecutive timepoints a linear mixed model will be constructed to assess the difference between the groups over all timepoints. The best covariance matrix over the timepoints will be assessed using the AIC and likelihood ratio. Included time points are 3, 6 and 12 months. The complications are categorical data and will be presented as number with frequencies and compared using the Chi-square test or Fisher's exact test, as applicable. For the psychological changes the analyses will be based on the intention-to-treat principle. Linear mixed model (LMM) analyses were conducted through a marginal model to evaluate the difference in secondary outcomes between the intervention group and control group.

Quality assurance and monitoring Quality assurance will be done via the study monitoring office of the Amsterdam university medical center. Every site will get one visit during the duration of the study.

Data will be verified and compared to external data sources such as the medical records and the paper filled in questionnaires.

Inclusion Criteria:

1. Surgically treated proximal humerus fracture, not older than two weeks
2. A high or very high level of neuroticism (cut-off score on NEO-FFI test off 37)
3. Minimal age of 18 years
4. The fracture must be a mono-injury (not part of a multi-injury incident)

Exclusion Criteria:

1. Any diagnosed psychiatric disorder that is not adequately managed with medication.
2. Not being able to communicate: language barrier, neurologic disorders
3. Paralysis on the affected arm
4. Not able to participate in online or real time psychological training
5. Any other fracture besides the proximal humerus fracture in an upper extremity
6. Head trauma with neurological symptoms

The investigator is blinded. The participants and care givers are due to the nature of the intervention not blinded.