Background. We developed a new model of stratified exercise therapy that distinguishes three knee osteoarthritis (OA) subgroups ('high muscle strength subgroup', 'low muscle strength subgroup', 'obesity subgroup'), which are provided subgroup-specific exercise therapy (supplemented by a dietary intervention for the 'obesity subgroup'). The present study aimed at exploring barriers and facilitators of this new model.Methods. Qualitative research design embedded within a cluster randomized

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... led trial in a primary care setting. A random sample from the experimental arm were interviewed (i.e., 15 patients, 11 physiotherapists and 5 dieticians). Qualitative data from these semi-structured interviews were thematically analyzed according to the grounded theory approach, to identify barriers and facilitators.Results. We identified six themes. Two themes applied to the model in general, emphasizing the perceived added value and applicability of the model. Three themes specifically applied to a subgroup. For the 'high muscle strength subgroup', the low number of supervised sessions was perceived advantageous by some and hindering by others. The 'low muscle strength subgroup' treatment was considered mostly comparable with usual care, therefore easy to provide. For the 'obesity subgroup', the potential of combining exercise therapy with weight loss was generally acknowledged, but physiotherapists perceived obesity difficult to address, and both physiotherapists and dieticians reported a lack of interprofessional collaboration. A sixth theme addressed barriers of knee OA treatment in general, with lack of motivation as most prominent barrier.Conclusion. This qualitative study revealed a number of barriers and facilitators of effective application of our model. Addressing these barriers and facilitators may enhance the effectiveness of the model.Trial registrationThe Netherlands National Trial Register (NTR): NL7463 (date of registration: 8 January 2019)