Objective: To verify the reliability and validity of the Turkish versions of the Hopkins Rehabilitation Engagement Rating Scale (HRERS) for knee arthroplasty.

Methods: A total of 51 consecutive participants, inpatients of an orthopedic clinic at the university hospital, were recruited between 2021-2022 June. Cronbach's alpha coefficient was used to assess internal consistency. By evaluating the scores of 51 retested patients one week later, the test-retest reliability was determined using the intraclass correlation coefficient (ICC). Pearson's correlation coefficient was used to assess the construct validity.

First of all, permission was obtained from Kortte et al., one of the developers of Hopkins Rehabilitation Engagement Rating Scale (HRERS), to have a Turkish version of HRERS via e-mail before starting the research study. The translation and the cultural adaptation of the Turkish version of the HRERS were accomplished in line with the stages outlined by Beaton et al.. Two independent native Turkish translators performed forward translation. One was a physiotherapist to ensure clinical consistency, and the other was a translator with no medical or clinical background to reveal vague concepts in the original questionnaire. A single consequent Turkish translation was formed from the combination of the two translations The Turkish scale was translated back into English by two English-native speakers who speak Turkish fluently, and the English version of the scale was compared to the original. A group of experts authorized the final version of the document in Turkish, which was backward translation. Translators reviewed the translations and compared certain inconsistencies.

Before the formal questionnaire, the pre-final Turkish version of the questionnaire was used for a pilot test. The Turkish translation was primarily applied to five participants for the detection of unintelligible questions or words. Turkish translation was applied to five participants in order to determine the questions or words that were not understood. We asked the participants the following questions: "Is there a question you don't understand?" "Are there any words you don't like?" Since the participants did not have any problems, no changes were made to the questionnaire, and the final Turkish version of the HRERS (HRERS-T) was provided.

Inclusion Criteria:

• Providing hospitalization and rehabilitation follow-up due to knee or hip arthroplasty by Süleyman Demirel University Hospital, Department of Orthopedics and Traumatology,
• Volunteering to participate in the study,
• It means getting a score of 24 or above when the Standardized Mini Mental Test Score is applied.

Exclusion Criteria:

• Having serious vision and hearing loss,
• Having an orthopedic, vestibular, neurological or mental problem such as upper and lower extremity pathology that may prevent or limit the application of the test protocol,
• Having a diagnosis of postural hypotension,
• Lack of cooperation,
• Being in the recovery period of an acute disease was determined as an exclusion criterion.

The required sample size for validation studies was reported as 2-20 participants per item on the scale (14). HRERS consists of five questions, thus we included at least fifty participants. A total of 51 consecutive participants, inpatients of an orthopaedic clinic at university hospital, were recruited between 2021-2022 June.