Study design and sample
This study was designed as a cross-sectional survey. It was approved by the XXX Research Ethics Committee (No. 201905XXXXX), and official written consent from each facility was obtained. Prior to the study, the research process was explained in detail to the participants. During the period from April to June 2019, random sampling was performed using the multi-stage sampling method. For factor analysis, the sample size for items must be 5-10 according to previous studies.14,15The Chinese PaArticular Scales have a total of 35 items; therefore, a sample size of 175-350 participants was appropriate for factor analysis in this study.16 The inclusion criteria of the participants were as follows: (1) ≥ 65 years old; (2) more than 6 months living at the facility; (3) having the language skills to fill out or answer the questionnaire; (4) severe joint contractures in any one important joint (knee, hip, ankle, shoulder, elbow and hand) with confirmation from a doctor, a nurse, or a therapist. Severe joint contractures were defined as 3 on a 4-point scale (loss > 2/3 of joint range of motion).17,18 Those with cognitive impairment and major mental illness diagnosed by physicians were excluded.