ObjectiveThis study aimed to assess the feasibility of a future trial comparing the collaborative care model with usual care for patients with musculoskeletal conditions and co-existing symptoms of anxiety and depression.DesignA single-centre, parallel-arm, one-to-one, randomised controlled trial design using a mixed-methods approach was used. semistructured interviews and focus groups were conducted post intervention with all participants and staff respectively to explore acceptability towards the model and identify recommendations for improvements.SettingAn orthopaedic rehabilitation outpatient tertiary hospital.ParticipantsAdult patients with musculoskeletal conditions and co-existing moderate or severe symptoms of anxiety and depression attending outpatient therapy appointments.InterventionThe collaborative care model consisted of a tailored management programme to facilitate the integration of care provided by physical and mental healthcare professionals. A case manager screened and coordinated targeted mental health support for participants. Participants allocated to usual care had no support from the case manager.Main outcomes measureFeasibility indicators (rates of recruitment, randomisation and retention), acceptability of clinical outcome measures, usage of additional resources and cost of intervention implementation.ResultsOf the 89 patients who provided consent to take part, 40 participants who matched the eligibility criteria were randomised to either the intervention (n=20) or usual care arm (n=20). Overall adherence to the intervention was 58.82%, while the withdrawal rate was 37.5% at 6 months. All of the 27 participants who were retained completed self-reported outcomes. Qualitative data highlighted that integrated mental health support was favourably perceived. In addition to prenegotiating protected psychology time, the need for operationalised communication between the case manager and clinicians was identified as a recommendation for a future trial.ConclusionsThe trial and intervention were acceptable to patients and healthcare professionals. While the findings demonstrate the feasibility of trial recruitment, a future trial will require optimised retention strategies to improve adherence and withdrawal rates.Trial registration numberNCT05018039.