The goal of this clinical trial is to investigate if physiotherapist supervised training improves neuromuscular control in patients suffering from traumatic anterior shoulder instability. The main question(s) it aims to answer are:

• Does physiotherapist supervised training improve shoulder neuromuscular control
• Does physiotherapist supervised training prevent recurring shoulder dislocations
• Is physiotherapist supervised training as good as surgery in improving shoulder neuromuscular control Participants will be randomised to either a training group or a no-training group.

Participants in the training group will undergo a 12 week training-program supervised by a physiotherapist.

Participants in the no-training group will receive a consultation with a shoulder surgeon, where information and general advice regarding the shoulder injury is provided.

Researchers will compare the training group to the no-training group to see if physiotherapist supervised training improves shoulder neuromuscular control in patients with traumatic anterior shoulder instability. The training group will also be compared to a historic group of patients with traumatic anterior shoulder instability, who underwent arthroscopic surgery.

• Aim: To investigate the effect of physiotherapist supervised training on shoulder neuromuscular control, and increase understanding of traumatic anterior shoulder instability.
• Main research questions:

A: Is supervised training in patients with traumatic anterior shoulder instability better in improving neuromuscular control, strength, apprehension and patient reported outcomes when compared to no training.

B: Is supervised training in patients with traumatic anterior shoulder instability better in preventing re-dislocations and need for surgical stabilisation when compared to no training.

C: Is supervised training in patients with traumatic anterior shoulder as good as Bankart surgery in improving neuromuscular control and patient reported outcome when compared to no training.

• Objectives for research question A:

To investigate if, in patients with traumatic anterior shoulder instability, a supervised 12-week training programme is better than no training in improving:

1. Neuromuscular control

2. Shoulder internal rotational strength

3. Shoulder apprehension

4. Patient reported outcomes

5. Clinical shoulder instability Outcomes are measured at a) the end of the 12-weeks intervention and b) 6 months after the beginning of the intervention. Furthermore, patient reported outcomes is also measured at 1 and 2 years after the beginning of the intervention.

   • Objective for research question B:

To investigate if, in traumatic anterior shoulder instability, a supervised 12-week training programme is better than no training in preventing a) re-dislocations and b) need for surgical stabilisation within the first 24 months.

• Objectives for research question C:

To investigate if, in patients with traumatic anterior shoulder instability, a specialised 12-week training programme is as good as arthroscopic Bankart surgery in improving:

1. Neuromuscular control
2. Shoulder internal rotational strength
3. Shoulder apprehension
4. Patient reported outcomes The training group is measured 6 months after the beginning of the intervention and the historic Bankart surgery group is measured 6 months after the surgery.

For all objectives neuromuscular control is investigated by determining a) shoulder joint position sense (JPS), b) shoulder reaction time, and c) shoulder sway length.

• Type of study: Pilot randomized controlled trial including 64 patients, which is allocated to either training og no-training (32 patients in each group).
• Time schedule: Recruitment and inclusion is planned to begin September 1st 2023 and is expected to last for 12-18 months. With a 2-year follow-up the complete study period is expected to last 3-3,5 years.
• Set-up: Patients presenting with shoulder instability in the outpatient clinic at Department of Orthopedic Surgery, Copenhagen University Hospital Hvidovre, will be recruited for the study. Patients who have signed an informed consent form will be randomised to either training- og no training-intervention and undergo examinations prior to, as well as three and six months after beginning of the intervention. All examinations will take place at the Copenhagen University Hospital Hvidovre. Patients in the training-group will be refered to training supervised by a physiotherapist. The training will take place at either Copenhagen University Hospital Hvidovre or a municipal rehabilitation center in Copenhagen. All examinations will include neuromuscular testing, accompanied by a clinical shoulder examination, strength measures and a validated electronic questionnaires regarding shoulder-related function. A pre-interventional 3D computed tomography scan will be performed to evaluate bone loss.

Inclusion Criteria:

• Age 18-40 years.
• Unilateral traumatic anterior shoulder instability.
• Willingness to adhere to the study protocol, herein attend follow-up.
• Ability to speak, read, and understand Danish.
• Ability to give written informed consent.

Exclusion Criteria:

• Instability in the opposite shoulder.
• Off-track lesion.
• For both shoulders: Former or planned surgery.
• For both shoulders: posterior, multi-directional or atraumatic instability.
• For both shoulders: traumatic rotator cuff or biceps tendon tear.
• For both shoulders: traumatic fracture of proximal humerus (other than Hill-Sachs lesion), clavicula, scapula (other than glenoid) or dislocation of sternoclavicular or acromioclavicular joints.
• For both shoulders: atraumatic shoulder pathologies (e.g. frozen shoulder, symptomatic osteoarthritis of the shoulder or acromioclavicular joints, acute tendinitis calcarean).
• Pregnancy.
• Terminal illness or severe medical illness: ASA score ≥3.