Abstract
BACKGROUND: As a recently available arthrometer, the Ligs arthrometer has been gradually used in clinical practice to assess knee stability. However, its reliability has not been fully established in this regard. The aim of this study was to assess the intra-rater and inter-rater reliability of the Ligs arthrometer for measuring anterior tibial translation (ATT) and the corresponding side-to-side difference (SSD) in healthy subjects. METHODS: A total of 40 healthy male subjects were recruited for this study between June 2023 and September 2023. Three examiners with different levels of experience tested the subjects with the Ligs arthrometer for ATT and SSD measurements. ATT values for both knees and the corresponding SSD at 90 N, 120 N, and 150 N were recorded for analysis. Statistical significance was determined using Student's t test or one-way analysis of variance (ANOVA). The intraclass correlation coefficient (ICC) was used to assess the intra-rater and inter-rater reliability of the Ligs arthrometer for ATT and SSD measurements. RESULTS: No subject asked to stop any test due to pain or discomfort. There was no significant difference among the three examiners in ATT measurements of the subjects' ipsilateral knees and SSD measurements at the same load (P > 0.05 for all). Furthermore, ATT measurements for the subjects' left and right knees measured by the same examiner were comparable (P > 0.05 for all). The Ligs arthrometer showed excellent intra-rater reliability (ICCs = 0.930-0.982) for ATT measurements and moderate to good intra-rater reliability (ICCs = 0.705-0.862) for SSD measurements. Similarly, its inter-rater reliability was excellent (ICCs = 0.911-0.930) for ATT measurements, but moderate (ICCs = 0.684-0.737) for SSD measurements. CONCLUSION: The Ligs arthrometer had moderate to excellent intra-rater and inter-rater reliability for ATT and SSD measurements in healthy knees. As compared with ATT measurements, SSD measurements showed lower intra-rater and inter-rater reliability at the same load. It is recommended that the tests be performed by the same examiner when using the Ligs arthrometer for SSD measurements.