Feasibility of Good Boost+ for Adults Awaiting Total Knee Replacement

Feasibility of a Community-Based Aquatic Exercise and Peer Support Intervention (Good Boost+) for Adults on Knee Replacement Waiting Lists: A Randomised Hybrid Type 1 Effectiveness-Implementation Feasibility Trial

The goal of this randomised controlled feasibility trial is to find out whether it is possible to run a larger study of the Good Boost+ community based rehabilitation programme for people waiting for a primary total knee replacement.

The study will look at how many people are willing to take part, whether they stay in the study, and whether they can follow the Good Boost+ programme as planned. It will also explore how acceptable the programme is to patients, NHS staff and leisure centre staff, and which outcome measures are most useful for a future full scale trial. The study will also look at what helps or hinders delivery of the programme in real world NHS and community settings.

The main questions it aims to answer are:

• How many people waiting for knee replacement surgery are willing to take part in the study
• Whether participants can continue with the Good Boost+ programme as planned over the study period
• Which outcome measures best capture any potential benefits of the programme
• How acceptable the programme is to patients, NHS and leisure centre staff
• What helps or makes it difficult to deliver the programme in practice.

Participants will be randomly assigned to one of two groups.

• Usual NHS care or
• Usual NHS care plus the Good Boost+ programme

Participants in the Good Boost+ programme will take part in six weekly group water based exercise sessions held in local swimming pools, as well as land based exercise sessions that can be done individually or by joining a virtual group. The exercise sessions are delivered through Good Boost's digital technology, using small waterproof tablet computers at swimming pools, and smartphones or computers for land-based sessions. Physiotherapy staff will provide guidance throughout, and volunteers will offer refreshments after pool sessions to support social connection.

All participants, including those receiving usual NHS care only, will be asked to complete an exercise diary, rate their knee pain each week, and complete short questionnaires at 6 and 10 weeks after joining the study.

Study Overview

• Status: Not yet recruiting
• Conditions: Arthroplasties, Knee Replacement; Osteoarthritis (Knee)
• Intervention / Treatment: Behavioral: Good Boost+; Other: Usual NHS Care

Detailed Description

Knee replacement surgery can greatly reduce pain and improve mobility for people with severe knee arthritis. However, NHS waiting times for surgery are often long, and many people experience worsening pain, reduced ability to work or take part in daily activities, low mood, and increased reliance on strong painkillers while they wait. These challenges can also affect recovery after surgery. Exercise programmes undertaken before surgery, known as 'prehabilitation', may help people feel better during the waiting period and may support better outcomes after surgery. Despite this potential, prehabilitation programmes are not widely available across the UK, and existing provision varies depending on where people live.

There is currently limited evidence about how best to deliver prehabilitation in a way that people waiting for orthopaedic surgery find acceptable, practical, and motivating. It is not yet clear which types of programmes people are most likely to use and stick with while waiting for knee replacement surgery. The Good Boost+ programme offers an approach that combines water-based group exercise in local swimming pools with flexible land-based exercise that can be completed individually or by joining a virtual group. The programme uses digital technology, and pool-based sessions are delivered in community leisure facilities rather than hospital settings. Exercising in water may be more comfortable for people with knee pain, and group sessions supported by refreshments afterwards provide opportunities for social interaction and peer support.

Early pilot work suggests this approach may be promising, but more evidence is needed to understand whether people awaiting knee replacement surgery are willing and able to take part, attend regularly, and complete the programme as intended when delivered alongside usual NHS care. With increasing demand for knee replacement surgery and long waiting times placing strain on patients and the NHS, there is an urgent need to explore new ways of supporting people during the waiting period.

This study is a two arm, parallel group, randomised controlled feasibility trial implementing the Good Boost+ programme for adults awaiting primary total knee replacement. An embedded mixed methods study will explore the acceptability of the intervention and identify determinants influencing the implementation of Good Boost+. The investigators aim to recruit 48 participants from orthopaedic services at NHS Trusts in South London. Participants will be randomly allocated in a 1:1 ratio to receive either usual NHS pre operative care alone or usual NHS pre operative care plus the Good Boost+ programme.

Participants allocated to the intervention group will receive usual NHS care plus the Good Boost+ programme. This includes an initial assessment and goal setting session with an NHS physiotherapist; six weekly group based water exercise sessions delivered in a leisure centre swimming pool using the Good Boost HUB app on a waterproof tablet computer; three home-based land exercise sessions per week using the Good Boost Move Together app on a smartphone or tablet computer; and weekly one to one support sessions with a physiotherapist delivered remotely. Following aquatic sessions, refreshments will be provided to encourage informal peer support. Participants in the control group will continue with usual NHS pre operative care.

Data collection will focus on feasibility outcomes, including recruitment, retention, adherence to the Good Boost+ programme, and completeness of data collection. Participants will complete weekly exercise diaries and short questionnaires at 6 and 10 weeks after randomisation. Patient and public contributors helped select the outcome measures and confirmed that the timing and burden of data collection would be acceptable to people awaiting knee replacement surgery. Adherence to the programme will be assessed using participant completed exercise diaries, direct participant contact, and usage data from the Good Boost digital applications.

Intervention fidelity will be monitored to ensure the programme is delivered as intended. Selected pool based sessions will be observed using a structured template, and a sample of remote physiotherapist support sessions will be audio recorded and assessed using the Motivational Interviewing Treatment Integrity (MITI) 3.3.1 coding system.

Qualitative interviews will be conducted with a sub sample of participants who received the intervention, and with NHS and leisure centre staff at sites where the Good Boost+ programme is being delivered and evaluated. These interviews will explore experiences of the programme, perceived acceptability, and barriers and facilitators to implementation. Approximately 25 to 30 NHS and leisure centre staff will also complete an adapted version of the Theoretical Framework of Acceptability questionnaire at two time points during the intervention delivery period.

The study will include the following stages: study set up and staff training; participant recruitment and baseline assessment; intervention delivery and data collection; qualitative interviews and fidelity assessment; and data analysis, interpretation and reporting. No formal interim analyses are planned, but feasibility metrics will be monitored throughout to ensure safe and effective conduct.

The findings from this feasibility trial will determine whether a larger, multi site effectiveness implementation trial of Good Boost+ is appropriate and will help refine the programme and its delivery model to best support people waiting for knee replacement surgery.

Alongside this feasibility trial, the research team is conducting a qualitative case study under a separate IRAS application to scope the barriers and enablers relevant to the future implementation of Good Boost+ for NHS patients awaiting total knee replacement across diverse geographic settings. The qualitative study is non-interventional and does not meet the definition of a clinical trial; therefore, it is not registered on ClinicalTrials.gov. It will be reported separately using appropriate qualitative research standards.

• Study Type: Interventional
• Enrollment (Estimated): 48
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Nicky Wilson; Phone Number: +442032995809; Email: nicky.wilson1@nhs.net

Study Locations

• United Kingdom
  • England
    • London, England, United Kingdom, SE5 9RS
      • King's College Hospital NHS Foundation Trust
      • Contact: Ines Reichert; Phone Number: +442032995795|; Email: i.reichert@nhs.net

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

Aged 18 years or over. Registered on a wait list for primary total knee replacement with sufficient time to complete the 6 week intervention and follow up assessments prior to surgery.

Moderate self reported intensity knee joint pain within the previous month, defined as ≥4 but <10 on the 11 point Numeric Pain Rating Scale (NPRS: 0 = no pain, 10 = worst pain imaginable).

Willing and able to participate in a six week programme of weekly group water-based exercise at specified leisure centre swimming pools in Southwark and three times weekly land-based exercise training in a private setting.

Willing to pay £4.30 for water-based exercise sessions 5 & 6. This fee is in line with the usual cost of over 60s group exercise classes at local leisure centres.

Access to a smart phone or tablet computer with internet access. Willing and able to accept either trial arm allocation. Willing and able to give informed consent.

Exclusion Criteria:

Individuals scheduled to have another major joint replacement (e.g. contralateral knee, hip or shoulder) within the study period.

Individuals on the waiting list for revision surgery of a previous knee replacement.

Individuals with active inflammatory arthritis (e.g., RA, PsA, lupus, axial SpA) that is clinically symptomatic or requires ongoing immunosuppressive therapy to control disease activity.

Individuals who self-report being advised by a healthcare professional not to exercise.

Individuals who have previously participated in water-based exercise sessions delivered via the Good Boost HUB application.

Participating or planning to participate in another interventional clinical study/trial during the study period that in the opinion of the investigator could affect the outcomes of this study.

Individuals unable to understand written or spoken English or communicate sufficiently well in English to participate despite assistance from a family member or friend.

Individuals unable to comply with the protocol / requirements of study participation.

Individuals with any other severe concomitant disease that, in the opinion of the investigator might interfere with trial procedures and/or assessments.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Supportive Care
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Single

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Usual NHS Care plus Good Boost+; Participants receive usual NHS pre operative care plus the Good Boost+ programme.	Behavioral: Good Boost+; Good Boost+ is a six week personalised exercise and peer support community based rehabilitation programme, combining water based group exercise and land based home exercise. Participants attend one group aquatic exercise session per week at a local leisure centre, delivered using the Good Boost digital application on a waterproof tablet computer. Participants also complete three land based exercise sessions per week at home or in another suitable space, accessed via the Good Boost Move Together app on a smartphone or tablet computer. An initial assessment and goal setting session is completed with an NHS physiotherapist. Participants receive weekly one to one remote support from a physiotherapist throughout the programme. Informal peer support is encouraged through refreshments provided after pool based sessions.; Other: Usual NHS Care; Standard NHS pre operative care for individuals awaiting primary total knee replacement, delivered according to local NHS practice. No additional structured exercise or prehabilitation components are provided
Other: Usual NHS Care; Participants receive usual NHS pre operative care only.	Other: Usual NHS Care; Standard NHS pre operative care for individuals awaiting primary total knee replacement, delivered according to local NHS practice. No additional structured exercise or prehabilitation components are provided

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Number (%) of eligible participants recruited to the trial	Recruitment will be assessed monthly from the start of recruitment until recruitment closes	At the end of the recruitment period (approximately 8 months after recruitment initiation)
Retention Rate at 10 weeks post-randomisation	The proportion (%) of participants who remain in the study and complete the Week 10 follow-up assessment.	Week 10 post-randomisation
Rate of Adherence to the Good Boost+ Programme	Adherence to the Good Boost+ programme will be measured weekly as the percentage of prescribed sessions completed by each participant over the 6-week programme. Adherence will be defined as engagement with ≥3 pool-based sessions, ≥9 land-based exercise sessions (self-reported), and at least one remote support session (telephone or video call) with the physiotherapist.	Baseline through to 6 weeks after starting the intervention
Proportion of participants with incomplete or missing outcome data.	The proportion (%) of participants with incomplete or missing outcome data at week 10 post-randomisation	Week 10 post-randomisation

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Acceptability of Good Boost+ / Usual NHS care to patients using Theoretical Framework of Acceptability (TFA) questionnaire scores	Scores on the adapted Theoretical Framework of Acceptability (TFA) questionnaire completed by patients waitlisted for knee replacement. This adapted TFA questionnaire has 7 items, each with a minimum score of 1 and maximum of 5 (with higher scores reflecting greater acceptability).	Baseline, Week 6 post-randomisation, Week 10 post-randomisation
Acceptability of Good Boost+ to NHS staff and leisure centre staff.	Scores on the adapted TFA questionnaire completed by NHS staff and leisure centre staff involved in delivering or supporting Good Boost+. This adapted TFA questionnaire has 7 items, each with a minimum score of 1 and maximum of 5 (with higher scores reflecting greater acceptability).	Baseline (at the start of intervention delivery at the relevant site); Mid-intervention (during month 4 of the 8-month intervention delivery period)
Acceptability of Good Boost+ to patients wait listed for knee replacement, NHS staff and leisure centre staff using qualitative interviews	Qualitative assessment of acceptability based on semi structured interviews with patients, NHS staff and leisure centre staff	8 weeks post-randomisation onwards (within 1 month of final pool based session)
Change in pain, function and stiffness (WOMAC score)	A 24-item disease specific measurement tool commonly used in hip and knee osteoarthritis. WOMAC enables an assessment of pain (5 items), stiffness (2 items) and physical functioning (17 items). The scores range between 0-20 for pain; 0-8 for stiffness; and 0-68 for physical function, with higher scores indicative of worse pain, stiffness and functioning.	Baseline, Week 6 post-randomisation, Week 10 post-randomisation
Change in Musculoskeletal Health (MSK HQ Score)	A 14-item generic measurement tool providing an overall evaluation of musculoskeletal health over the past two weeks. The MSK-HQ is scored on a range of 0-56, with higher scores indicating better musculoskeletal health status.	Baseline, Week 6 post-randomisation, Week 10 post-randomisation
Change in Generic Health Status (EQ 5D 5L Score)	EQ-5D-5L provides a generic measure of quality of life. It consists of five domains (mobility, self-care, usual activities, pain/discomfort and anxiety/depression) with five categorical levels for each domain. Higher scores within these five domains indicate worse health status. The instrument also contains a general health VAS (0 to 100), where 100 = best health and 0 = worst health.	Baseline, Week 6 post-randomisation, Week 10 post-randomisation
Change in Mental Well Being (WEMWBS Score)	A 14-item tool that measures mental well-being. Each item is scored from 1 (none of the time) to 5 (all of the time). A total scale score is calculated by summing the individual item scores. The minimum score is 14 and the maximum is 70, with higher scores indicating higher mental well-being.	Baseline, Week 6 post-randomisation, Week 10 post-randomisation
Change in Patient Global Assessment (PGA Score)	The Patient Global Assessment (PGA) is a single question about how participants' knee osteoarthritis is affecting them on that day; using a 5-point Likert scale anchored with 1 = very good [asymptomatic and no limitation of normal activities] and 5 = very poor [very severe symptoms which are intolerable and inability to carry out all normal activities]. Change from baseline in PGA will be calculated as the post-baseline value minus the baseline, with lower change score being more favourable.	Baseline, Week 6 post-randomisation, Week 10 post-randomisation
Change in Social Support (MOS Social Support Survey Score)	A 19-item survey that measures perceived availability of functional social support. The survey is composed of four separate social support subscales: emotional/informational support (8 items), tangible support (4 items), affectionate support (3 items), positive social interaction (3 items) and one additional item not included in any subscale. Mean scores for each subscale are calculated with response scores ranging from 1-5. In addition, the mean of all 19 items can be calculated to give an overall support index. Higher scores indicate more social support.	Baseline, Week 6 post-randomisation, Week 10 post-randomisation
Change in Pain Intensity (Numerical Pain Rating Scale)	The Numerical Pain Rating Scale (NPRS) is an 11-point scale for self-report of pain. Respondents select a whole number (0-10) that best reflects the intensity of their knee pain. The anchors are 0 = no pain and 10 = the worst pain imaginable. The NPRS can be administered graphically for self-completion or verbally (e.g. by telephone).	Baseline; Weekly during the 6-week intervention period; Week 10 post-randomisation.
Healthcare Resource Use	Self reported healthcare utilisation measured using a healthcare resource use questionnaire, which includes 8 items about healthcare utilisation and estimated spending due to knee symptoms.	Baseline, Week 10 post-randomisation
Barriers and enablers to implementation	Identification of determinants of implementation based on semi structured interviews with patients, NHS staff and leisure staff	8 weeks post-randomisation onwards (within 1 month of final pool based session)
Fidelity of intervention delivery (Good Boost+ Water Based Sessions)	Fidelity of intervention delivery within pool settings will be monitored using a pre-specified fidelity checklist, to evaluate quality of sessions as delivered per protocol. The checklist includes 22 quantitative items, scored on a Likert scale of high (=2), moderate (=1) and low (=0), with a maximum possible score of 44 indicating optimal fidelity to the protocol. Assessments will be conducted at pre-defined timepoints across the trial by trained research staff. Qualitative observations and notes will also be made regarding deviations from or adaptations to the protocol that may be influenced by contextual factors of the specific session.	Mid-intervention (end of week 3 of the 6-week intervention delivery period); End of intervention (week 6 of the 6-week intervention delivery period)
Fidelity of Physiotherapist Support Sessions	20-30% of recorded physiotherapy support sessions for Good Boost+ intervention participants will be selected for fidelity checking, using the Motivational Interviewing Treatment Integrity (MITI) 3.3.1 coding system. The MITI will be used to assess the overall fidelity/quality of the consultations, generating global scores across 5 dimensions: Evocation, Collaboration, Autonomy/Support, Direction, and Empathy. Global scores are on a five-point Likert scale, with 1 representing low fidelity to the motivational interviewing protocol and 5 representing high fidelity. Alongside global scores, counts of specific motivational interviewing behaviours are tallied in seven categories.	Weekly during the 6-week intervention period

Collaborators and Investigators

• Sponsor: King's College Hospital NHS Trust
• Collaborators: King's College London; Imperial College London; University of Leeds; University of Leicester; National Institute of Health and Care Research, United Kingdom

Study record dates

Study Major Dates

• Study Start (Estimated): June 1, 2026
• Primary Completion (Estimated): November 1, 2026
• Study Completion (Estimated): February 1, 2028

Study Registration Dates

• First Submitted: January 12, 2026
• First Submitted That Met QC Criteria: April 9, 2026
• First Posted (Actual): April 16, 2026

Study Record Updates

• Last Update Posted (Actual): April 16, 2026
• Last Update Submitted That Met QC Criteria: April 9, 2026
• Last Verified: April 1, 2026

More Information

Terms related to this study

• Keywords: Feasibility; Implementation; Randomised controlled trial; Prehabilitation; Total Knee Replacement
• Additional Relevant MeSH Terms: Musculoskeletal Diseases; Arthritis; Joint Diseases; Rheumatic Diseases; Osteoarthritis; Osteoarthritis, Knee
• Other Study ID Numbers: IRAS Project ID: 349699; NIHR208155 (Other Grant/Funding Number: National Institute for Health and Care Research)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: UNDECIDED
• IPD Plan Description: Data sharing plans have not yet been finalised. This is a feasibility trial with a small sample size and mixed methods data. The suitability and governance requirements for sharing individual participant data will be reviewed after study completion

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No