This study adopted a randomized, placebo-controlled, and qualitative mixed design. Qualitative data were collected using a semi-structured interview questionnaire.~The study was conducted in the physical therapy and rehabilitation outpatient clinic of a public hospital in Türkiye. The study population consisted of all patients admitted to the outpatient clinic for osteoarthritis-related pain. The data collection process continued from December 2017 to August 2018 and was reported in accordance with the Consolidated Standards of Reporting Trials (CONSORT) guidelines. A pilot study was conducted with five patients before data collection.~Patients diagnosed with osteoarthritis by a physical therapy and rehabilitation specialist according to ACR criteria were randomized into the study by the University Biostatistics Unit. The initial sample consisted of 72 patients divided into intervention (n=36; St. John's wort oil) and placebo control (n=36; olive oil) groups. However, six experimental group participants were excluded because they either could not be contacted on the phone during the follow-ups (n=4) or stated that they would be out of town for a long time (n=2). Six control group participants were also excluded because they either could not be contacted on the phone during the follow-ups (n=3), did not want to keep up with the intervention (n=1), or wanted to withdraw from the study (n=2). Therefore, the final sample consisted of 30 experimental and 30 control group participants.
This study investigated the effect of St. John's Wort oil on pain intensity and physical functions in people with knee osteoarthritis. This study adopted a randomized, placebo-controlled, and qualitative mixed design. The sample consisted of 60 patients randomized into intervention (n=30) and placebo control (n=30) groups. The experimental group participants were treated with St. John's Wort oil three times a week for three weeks, while the placebo control group participants were treated with olive oil three times a week for three weeks. Quantitative data were collected using a patient identification form, the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and the Visual Analogue Scale (VAS). Qualitative data were collected through semi-structured interviews. .