Intra-rater and inter-rater reliability of robotic arthrometer DYNEELAX®

Purpose

The purpose of our study was to test the intra-rater and inter-rater reliability of the DYNEELAX® arthrometer in healthy subjects. Since rotational laxity will be measured for the first time in humans, indications for normative values will also be presented.

Methods

Knee anterior laxity and rotational laxity using a DYNEELAX® arthrometer were assessed in 73 subjects (39 females and 34 males). An intraclass correlation coefficient was calculated to evaluate the intra-rater and inter-rater reliability of the DYNEELAX®.

Results

An intraclass correlation coefficient for intra-rater reliability ranges from 0.631 (95% confidence interval; [CI]: 0.47–0.75) to 0.699 (95% CI: 0.56–0.80) and from 0.916 (95% CI: 0.87–0.95) to 0.94 (95% CI: 0.91–0.96) for anterior knee laxity and rotational knee laxity, respectively. An intraclass correlation coefficient for inter-rater reliability ranges from 0.578 (95% CI: 0.40–0.71) to 0.646 (95% CI: 0.44–0.78) and from 0.822 (95% CI: 0.57–0.91) to 0.933 (95% CI: 0.89–0.96) for anterior knee laxity and rotational knee laxity, respectively.

Conclusions

The DYNEELAX® arthrometer has good to excellent intra-rater and inter-rater reliability for rotational knee laxity and moderate intra-rater reliability for anterior knee laxity in healthy subjects. Future studies should investigate the clinical significance of anterior and rotational laxity measured with the DYNEELAX® arthrometer in patients with knee pathology, as both laxities are critical for assessing the integrity of the intra-articular structures of the knee in clinical practice.

Level of evidence

Level IV.