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Objective To evaluate the influence of viscosupplementation on osteoarthritic knee arthrokinematics analyzed by VAG. It is considered that intra-articular hyaluronic acid injection may improve the function of synovial joints by recovery of friction-reducing properties of articular environment. Design Thirty-five patients with knee osteoarthritis (grade II according to the Kellgren-Lawrence system) and 50 asymptomatic subjects were enrolled in the study. Patients were analyzed at 3 time points: 1 day before and 2 weeks and 4 weeks after single injection of 1.5% cross-linked hyaluronate. Control subjects were tested once. The vibroarthrographic signals were collected during knee flexion/extension motion using an accelerator and described by variation of mean square (VMS), mean range (R5), and power spectral density for frequency of 50 to 250 Hz (P1), and 250 to 450 Hz (P2). Results Patients before viscosupplementation were characterized by about 2-fold higher values of vibroarthrographic parameters than controls. Two weeks after the procedure, the values of R5, P1, and P2 significantly decreased, in comparison to pre-injection. At 4 weeks post-injection, we noted a significant increase in R5, P1, and P2 values, when compared to 2 weeks post-injection. Finally, at 4 weeks post-injection, the level of VMS, R5, and P2 parameters did not differ from values obtained at pre-injection. Conclusions We showed that viscosupplementation may be effective in providing arthrokinematics improvement, but with a relatively short period of duration. This phenomenon is observed as decreased vibroacoustic emission, which reflects a more smooth movement in the joint.

Vibroarthrography (VAG) is a non-invasive and potentially widely available method supporting the joint diagnosis process. This research was conducted using VAG signals classified to five different condition classes: three stages of chondromalacia patellae, osteoarthritis, and control group (healthy knee joint). Ten new spectral features were proposed, distinguishing not only neighboring classes, but every class combination. Additionally, Frequency Range Maps were proposed as the frequency feature extraction visualization method. The results were compared to state-of-the-art frequency features using the Bhattacharyya coefficient and the set of ten different classification algorithms. All methods evaluating proposed features indicated the superiority of the new features compared to the state-of-the-art. In terms of Bhattacharyya coefficient, newly proposed features proved to be over 25% better, and the classification accuracy was on average 9% better.

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Background. Osteoarthritis is one of the most common dysfunctions of the musculoskeletal system and viscosup­plementation is becoming an increasingly popular treatment in OA. However, current knowledge regarding biomechanical changes in synovial joints reveals many discrepancies. Therefore, the aim of our study was to evaluate the effect of visco­supplementation on knee joint arthrokinematics as analyzed by vibroarthrography. Material and methods. Seventeen individuals diagnosed with moderate knee osteoarthritis (VSC) were examined before and after a single injection of hyaluronate. A control group consisted of 30 asymptomatic individuals. During alter­nating extension/flexion of the knee joint, a 6-second vibroarthrographic signal was recorded using an accelerometer. The following parameters were calculated: variance (VMS), amplitude (R4), and spectral power density in the 50-250 Hz (P1) and 250-450 Hz (P2) bands. Results. Statistical analysis showed significant differences (p<0.05) in the values of R4 and P2, which were higher in the VSC group than among the controls. After viscosupplementation, the values of R4, P1 and P2 in the VSC group de­creased to a level not significantly different from that seen among the controls. Conclusions. 1. After a single intra-articular HA injection, joint motion-related vibrations were reduced, which was recorded as a decreased intensity of vibroacoustic emission. 2. This suggests that the use of viscosupplementation in pa­tients with moderate knee osteoarthritis may improve qualitative aspects of arthrokinematics.