Patients who have undergone lower limb or knee surgery are often required to participate in rehabilitative exercises to regain or maximise movement and function in the affected leg. Physiotherapy interventions for rehabilitation can be painful, uncomfortable, and tedious, reducing compliance and limiting the movement and function achieved by the patient.

Clinical studies have reported improvements in pain, compliance and outcomes by incorporating Virtual Reality (VR) into care. Evidence suggests that more Immersive VR (IVR) is effective in rehabilitation, while being cost-effective, with few adverse side-effects. Previous research by this team with adult burn patients and paediatric upper limb rehabilitation patients indicate that IVR could help reduce pain, increase compliance and improve care experiences and outcomes.

The objective of the study is to investigate the feasibility and perceived impact of the Immersive Virtual Reality (IVR) intervention as a tool in physiotherapy rehabilitation for children (aged 11-16) after lower limb or knee surgery.

The study will take the form of feasibility and proof of concept trial using IVR as a physiotherapy rehabilitation tool following lower limb or knee surgery for children (aged 11 - 16). It will examine the feasibility, acceptability, usability, and efficacy of the IVR system from the perspectives of the children, parents and staff. The mixed-method approach (collecting quantitative and qualitative data):

Assess changes in anxiety, pain and movement during daily physiotherapy rehabilitation sessions after surgery and before discharge from hospital, based on:

• Child's anxiety ratings before physiotherapy
• Child's pain ratings after physiotherapy
• Practitioner's ratings of movement during physiotherapy Assess child, parent / carer and staff perceptions of and satisfaction with IVR as a tool to enhance the experience and outcomes of physiotherapy.

Assess the perceptions of therapeutic and clinical staff on the viability of the IVR as a tool for assisting in rehabilitation physiotherapy in the hospital setting.

Procedure Before consent is taken, child participants will be offered a 5 minute exposure to the HMD IVR equipment and another similar game, to familiarise themselves with the equipment, check there are no problems, and avoid unnecessary distractions and confusion during the IVR scenario itself. Patients will then use the IVR during each physiotherapy session after surgery until their discharge from hospital, which is expected to comprise one 10 minute session per day for 3-5 days. During each session, child participants will rate their anxiety, perceived pain and feedback any feelings about the experience. Physiotherapists will record the range of movement and strength using standardised measures to check for improvements.

Qualitative feedback will be gathered through interviews with children, their parents, and practitioners, focusing on experiences, satisfaction, effectiveness, acceptability, and practicality of the IVR intervention. Further feedback on IVR usability will be obtained from practitioners.

Data Analyses Descriptive statistics for anxiety, pain and movement collected before, during and after physiotherapy sessions will be calculated. Repeated measures analyses will be conducted to assess changes over time in each outcome.

Interpretive analyses will be conducted to establish whether demographic differences influence dependent variables.

Findings for anxiety, pain and movement under IVR and for SUS (usability scale) ratings will also be compared with pre-existing norm-related evidence and other relevant published clinical outcomes from physiotherapy studies. However, in this small sample, statistical analyses will be treated tentatively. Future larger scale work will strengthen any tentative findings made from this small-scale feasibility study.

Qualitative data from all interviews will be collated and analysed for themes which address the aims of the study using established thematic analysis processes. This will involve a process of careful reading, coding and comparison in order to identify important patterns in the data, focused on answering the aims of the study. Themes will be generated based upon the analysis process, which will be discussed and refined within the research team. Data will be stored, organised and analysed in NVivo.

Inclusion Criteria:

• aged 11-16.
• able to speak and understand English.
• receiving physiotherapy rehabilitation treatment as an inpatient following lower limb or knee surgery, in order to restore or improve movement and function.

Exclusion Criteria:

• - Injuries to the face or head that could hinder the correct positioning of the headset or pose an infection risk
• A learning impairment that could hinder the understanding of the task
• A history of severe motion sickness or vertigo.
• Mental health problems

In order to avoid unnecessary psychological or physical distress, it is expected that we will exclude those with acute mental health symptoms as assessed by clinicians, where the use of VR might be contraindicated.

Children with mild, well controlled mental health problems will not be excluded from the study, as long as parents, child, and clinicians are in agreement. VR can occasionally cause dizziness or nausea in individuals with motion sickness, and although designed to be as enjoyable as possible, activities in the VR may cause anxiety in those with vertigo. These issues will be identified in the information sheets and discussed with parents.