ISAKOS Congress 2021

2021 ISAKOS Biennial Congress ePoster

 

Assessment of inter-rater reliability of a new device to measure anterior knee laxity. A cadaver study

Alessandra Scaini, MD, Brescia ITALY
Maristella Francesca Saccomanno, MD, Brescia ITALY
Alessandro Colosio, MD, Brescia ITALY
Marco Adriani, MD, Brescia, Brescia ITALY
Marcello Motta, MD, Brescia ITALY
Mac Donald Tedah Djemetio, MD, Brescia ITALY
Emanuele Maggini, MD, Brescia ITALY
Giuseppe Bertoni, MD, Brescia, Lombardia ITALY
Martina Re, MD, Brescia, Brescia ITALY
Giuseppe Frizziero, MD, Verona ITALY
Giuseppe Milano, MD, Brescia, BS ITALY

Spedali Civili di Brescia, Università degli Studi di Brescia, Brescia, Lombardia, ITALY

FDA Status Not Applicable

Summary

BLU-DAT is a new device for measuring anterior knee laxity. This cadaver study showed that it has a very good inter-rater reliability and good agreement with stress radiographs.

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Abstract

Background

The quantification of anterior knee laxity is very important in clinical practice both for assessment of anterior cruciate ligament (ACL) injuries and in the outcome evaluation of different ACL reconstruction techniques. Several devices have been developed to make knee laxity testing more accurate and reliable. Many factors related to the setting, examiner, and patients tend to undermine the reliability and accuracy of these devices. Nowadays, despite the introduction of new devices, there are not practical arthrometers for the outpatient setting that can minimize these factors while maintaining excellent reproducibility and consistent agreement with reference standard like stress radiographs. The purpose of the present study was to evaluate the inter-rater reliability and agreement with a gold standard of a new device to measure anterior knee laxity (BLU-DAT).

Methods

Laboratory study. Five fresh frozen cadaveric knees were used. All the specimens had no signs of advanced osteoarthritis or previous surgery, and an intact ACL. Anterior knee laxity was texted by performing the Lachman test. Quantification of anterior tibial translation (ATT) was measured simultaneously by the BLU-DAT and by lateral radiographs of the knee (in resting and loading positions) by placing three 1-mm titanium marker beads in both the distal femur and proximal tibia. The ATT was acquired under three different loading conditions: 7 kg (69 N), 9 kg (88 N), and maximum manual traction (MMT). The tests were performed by five examiners with different skill levels. Tests were performed on the same specimens in the intact state and again after arthroscopic excision of the ACL. Each examiner performed 30 evaluations by testing every specimen 6 times (with and without ACL under 3 loading conditions). Overall, 150 tests were carried out.
Inter-observer reliability was assessed with the intraclass correlation coefficient (model 2,1) for single and average measures. The Bland-Altman method was used to assess agreement between the two measurements of ATT. Confidence intervals were calculated at 95% confidence level for ICCs. Agreement was expressed as mean and standard deviation of the differences. In addition, upper and lower limits of agreement (LOA) were reported and 95% confidence intervals (CI) were calculated for the mean difference and estimated LOAs.

Results

Analysis of inter-observer reliability showed ICC value of 0.63 (95% CI = 0.45 – 0.78) and 0.90 (95% CI = 0.81 – 0.95) for single and average measurement, respectively. The SEM was 0.52.
Analysis of agreement between BLU-DAT and radiographic measurements showed a mean difference equal to 0.83 mm + 2.1 mm (95% CI: 0.55 – 1.11). Upper LOA was equal to 4.9 mm (95% CI: 5.39 – 4.41). Lower LOA was equal to -3.2 mm (95% CI: -2.71 - -3.69).

Conclusion

The results of the present study showed that the BLU-DAT testing device has a good to very good inter-rater reliability and good agreement with a gold standard such as stress radiographs.

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