A Novel Method of Evaluating Knee Joint Stability of Patients with Knee Osteoarthritis: Multiscale Entropy Analysis with A Knee-Aiming Task

Abstract

Deteriorating knee stability is a local risk factor that reflects the occurrence and aggregative of osteoarthritis (OA). Despite the many biomechanics-based methods for assessing the structural stability of knee joints in clinics, these methods have many limitations. The stability of the knee joint relies on not only biomechanical factors, but also proprioception and the central nervous system. In this study, we attempt to depict the stability of knee joint from a holistic viewpoint, and a novel index of knee joint stability (IKJS) was thus extracted. We compared the differences of IKJS in 57 healthy volunteers and 55 patients with OA before and after total knee replacement (TKR). Analysis of Variance results demonstrated that there existed significant differences in IKJS among the three participating groups (<0.0001). Also, the IKJS of the operated leg in patients with knee OA increased remarkably after TKR (p < 0.0001). Furthermore, the results of the experiment suggested that the IKJS has sufficient reproducibility (ICC = 0.80). In conclusion, the proposed IKJS that employs the knee-aiming task is feasible for quantitatively determining knee stability. It can provide a potentially valuable and convenient tool to evaluate the effect of postoperative rehabilitation for patients with knee OA.

Conflict of interest statement

The authors declare that they have no competing interests.

Figures

Figure 1

Schematic diagram of the knee-aiming task.participant sit on a chair or a bad with a Knee-Aiming Task.

Figure 2

The flowchart of data analysis. Data gathered from the experiment first through a series of Data Pre-Processing. Then the MSE approach was further utilized to extract a novel biometrics-termed index of knee joint stability (IKJS) from the displacement time series in order to evaluate knee stability.

Figure 3

On the 1~30 scale of the MSE, a comparison between three groups. The MSE of displacement time series at scales 12–15 was observed to be different among three groups.

Figure 4

Comparisons between IKJS results of three groups. IKJS of healthy volunteers is better than patient, and postoperative patient comes closer to the healthy volunteers.

Figure 5

Paired t-test results of IJKS. (A) For operated leg pre/post-surgery. (B) For non-operated leg pre/post-surgery. The IKJS of operated leg has a significant improvement while non-operated leg has no significant change.