A total of @ people with medial knee OA ( mean SD age @ @ years , mean SD body mass index @ @ kg/m ( @ ) , and radiographic disease severity @ % mild , @ % moderate , and @ % severe ) who completed a @-week physiotherapist-supervised exercise trial were randomly allocated to @ @-minute physiotherapy booster sessions ( delivered by @ physiotherapists in private clinics ) or no booster sessions for the subsequent @ weeks .