Background Patient‐reported outcome measures (PROMs) are increasingly used to establish the value of health care. In order to reflect value, PROMs should measure outcomes that matter to patients. However, patients are not always involved in the development of PROMs. This study therefore aimed to investigate whether PROMs, which were developed without patient involvement, are relevant to patients and whether the level of importance allocated towards aspects of these PROMs varies between patient groups. Methods All patients from 20 Dutch hospitals undergoing hip or knee surgery in 2014 were invited to a PROMs survey. Participants were asked to rate the importance of each of the items in the HOOS‐Physical Function Short form or the KOOS‐Physical Function Short form, the EQ‐5D and the NRS pain. Results Most outcomes were considered important. However, 77.7% of hip surgery patients rated being able to run as unimportant. Being able to kneel (32.7%) or squat (39.6%) was not important to a considerable minority of knee surgery patients. Pain, especially during rest, was considered very important by both hip (68.2%) and knee (66.5%) surgery patients. Patients who were older, male, experienced overall bad health and psychological health considered many items from the PROMs less important than other patients. Discussion Patients differ in what they consider important. Health‐care professionals should explore patients’ preferences and discuss which treatment options best fit patients’ preferences. Additionally, if PROMs are used in performance measurement, further research is needed to look at whether and how variation in patient preferences can be taken into account.