Reliability of levator scapulae index in subjects with and without scapular downward rotation syndrome

• Intrarater reliabilities in both groups were excellent for measuring LS length with the LSI.
• Interrater reliability was good in subjects with SDRS; however, interrater reliability was moderate in subjects without SDRS.
• LSI is a reliable method to measure LS length and is more reliable for subjects with SDRS.

ObjectivesThe objective of this study was to introduce levator scapulae (LS) measurement using a caliper and the levator scapulae index (LSI) and to investigate intra- and interrater reliability of the LSI in subjects with and without scapular downward rotation syndrome (SDRS).DesignTwo raters measured LS length twice in 38 subjects (19 with SDRS and 19 without SDRS).Main outcome measuresFor reliability testing, intraclass correlation coefficients (ICCs), standard error of measurement (SEM), and minimal detectable change (MDC) were calculated.ResultsIntrarater reliability analysis resulted with ICCs ranging from 0.94 to 0.98 in subjects with SDRS and 0.96 to 0.98 in subjects without SDRS. These results represented that intrarater reliability in both groups were excellent for measuring LS length with the LSI. Interrater reliability was good (ICC: 0.82) in subjects with SDRS; however, interrater reliability was moderate (ICC: 0.75) in subjects without SDRS. Additionally, SEM and MDC were 0.13% and 0.36% in subjects with SDRS and 0.35% and 0.97% in subjects without SDRS. In subjects with SDRS, low dispersion of the measurement errors and MDC were shown.ConclusionsThis study suggested that the LSI is a reliable method to measure LS length and is more reliable for subjects with SDRS.