Abstract
BACKGROUND: Temporomandibular disorders (TMDs) are a group of musculoskeletal conditions characterized by orofacial pain and functional impairments. The Jaw Functional Limitation Scale (JFLS) is a patient-reported outcome measure recommended by the Diagnostic Criteria for Temporomandibular Disorders. The aim of the study was to translate and cross-culturally adapt the JFLS for the Arabic language and to test its validity and reliability in Egyptian patients with TMDs. METHODS: The JFLS was translated and cross-culturally adapted into Modern Standard Arabic according to standard guidelines. The construct validity was assessed in 54 patients with TMD who completed the Arabic versions of JFLS (JFLS-Ar), the Arabic version of Oral Health Impact Profile 5 (OHIP5-Ar), and the Numerical Pain Rating Scale (NPRS). Test-retest reliability was estimated in 30 participants who completed the JFLS-Ar again within seven days. Cronbach's alpha coefficient was used to determine the internal consistency of the items in the JFLS-Ar. RESULTS: The total score (0-200) of the JFLS-Ar showed moderate correlations with both OHIP5-Ar (ρ = 0.58, p < 0.001) and NPRS (ρ = 0.56, p < 0.001). The global score (average of the three domain scores, 0-10) showed moderate correlations with both OHIP5-Ar (ρ = 0.56, p < 0.001) and NPRS (ρ = 0.56, p < 0.001). The short form global score (average of 8 specific items, 0-10) showed moderate correlations with both OHIP5-Ar (ρ = 0.61, p < 0.001) and NPRS (ρ = 0.6, p < 0.001). The total score showed excellent test-retest reliability with an ICC of 0.97 (95% CI: 0.95-0.99), Standard Error of Measurement (SEM) of 6.17, and Minimal Detectable Change (MDC) of 17.1. The global score showed excellent test-retest reliability with an ICC of 0.97 (95% CI: 0.93-0.98), SEM of 0.38, and MDC of 1.06. The short form global score showed excellent test-retest reliability with an ICC of 0.99 (95% CI: 0.98-0.995), SEM of 0.2, and MDC of 0.55. The Cronbach's alpha coefficient of the 20-item JFLS-Ar and the 8-item JFLS-Ar was 0.938 and 0.852, respectively. CONCLUSIONS: The JFLS-Ar represents a valid and reliable instrument for use in Arabic-speaking patients with TMDs.