This pilot randomised clinical trial will evaluate the feasibility, acceptability, and safety of an early, home-based stationary cycling intervention added to standard postoperative home exercises following knee arthroplasty. The study will also evaluate the feasibility of the study procedures required for a subsequent full-scale randomised clinical trial.
A total of 24 participants will be randomised in a 1:1 ratio to either the cycling intervention group or the control group. Both groups will receive the standard postoperative home exercise programme. Participants allocated to the cycling intervention group will additionally perform the structured home-based cycling programme for eight weeks. Participants allocated to the control group will follow the standard postoperative home exercise programme without structured cycling during the intervention period. Outcome assessors conducting the 10-week follow-up assessments will be blinded to group allocation.
The pilot will address several aspects of feasibility, including screening and recruitment, retention and completion of follow-up, adherence to the allocated study intervention, acceptability of the cycling intervention, safety, and the practicality and burden of study procedures. In the control group, adherence to the instruction to refrain from cycling during the intervention period will also be assessed. The study will additionally examine the practical and logistical feasibility of delivering the cycling intervention at home, including access to stationary bikes and, where required, provision of bikes through an external rental service.
Participants will complete selected patient-reported outcome measures preoperatively and undergo a baseline assessment two weeks after surgery, before randomisation. Preoperative assessments are included for measures for which assessment two weeks after surgery is not considered appropriate or informative. Following the baseline assessment and randomisation, participants will receive the allocated intervention. The main follow-up assessment will be conducted at 10 weeks after surgery, following completion of the eight-week cycling intervention.
Recruitment feasibility will be assessed throughout the recruitment period, including screening, eligibility, recruitment rate, and reasons for declining participation. Retention will be assessed by attendance at the 10-week follow-up and completion of planned assessments.
Intervention feasibility will include adherence to the prescribed cycling dose using the SENS Motion® activity tracker, participant-reported symptoms related to cycling, and acceptability of the intervention. In the control group, adherence to the instruction to refrain from cycling will also be assessed. Safety will be assessed by recording and describing adverse events and serious adverse events occurring during the study, including events potentially related to the cycling intervention.
Feasibility of the study procedures will include completion and burden of questionnaires and physical and performance assessments, as well as the duration and practical challenges associated with baseline and follow-up assessments, intervention delivery, equipment, and study visits. The practical and logistical feasibility of providing stationary bikes through an external rental service will also be evaluated. Participant feedback, qualitative interviews, and feedback from project staff and the clinical team will provide additional information on practical aspects of study conduct.
Completion of patient-reported outcome measures will be assessed as a separate feasibility aspect. Overall completion, completion of individual questionnaires, and missing questionnaire items will be examined to identify measures or items that may be difficult to complete, perceived as less relevant, or contribute substantially to assessment burden. These findings may inform refinement of the outcome assessment battery for the subsequent full-scale trial.
Predefined progression criteria will be used to guide the decision whether to progress to a future full-scale randomised clinical trial. The criteria address recruitment rate, adherence in the intervention and control groups, 10-week follow-up completion, and completion of baseline physical and performance assessments. A traffic-light system will be used to indicate whether progression is feasible as planned, may require modifications or further clarification, or is not recommended in its current form. The progression criteria will be considered together with additional qualitative and practical information collected during the pilot.
The primary feasibility evaluation will take place at 10 weeks after surgery. Clinical and patient-reported outcomes collected during the pilot will be analysed descriptively to provide exploratory information on postoperative recovery, outcome variability, and potential between-group differences. The Knee injury and Osteoarthritis Outcome Score (KOOS) will be assessed using the Pain, Symptoms, Activities of Daily Living (ADL), and Quality of Life subscales preoperatively and at the 10-week follow-up. These four subscales comprise the KOOS4. The proportion of participants achieving a minimally important change in KOOS4 will be explored descriptively.. These data will also contribute to planning the outcome assessment and statistical design of the subsequent full-scale randomised clinical trial.
Selected patient-reported outcome measures will also be collected at 6 and 12 months after surgery. These data will provide exploratory information on longer-term outcomes and the feasibility of longer-term follow-up. The longer-term follow-up will not determine the main feasibility evaluation at 10 weeks.
Overall, the findings from the pilot will be used to determine whether modifications to the intervention, study procedures, recruitment or retention strategies, or outcome assessment battery are required before conducting a subsequent full-scale randomised clinical trial.
