Discrimination of knee osteoarthritis patients from asymptomatic individuals based on pain sensitivity and knee vibroarthrographic recordings.

OBJECTIVE: Recording of knee vibroarthrographic (VAG) activity during activities of daily living (ADL) can contribute to diagnose knee osteoarthritis (KOA). However, classifying KOA patients based on knee VAG during ADL has been an elusive problem not related to knee pain. Therefore, the aims of this study was to classify KOA patients based on (1) VAG during ADL and (2) knee pain sensitivity and then compare their results. APPROACH: The experimental procedure consisted of the recording of VAG signals during four ADLs (over-ground gait, stairs descent, stairs ascent and sit-to-stand) from eight patellar and peri-patellar locations in 20 KOA and 20 asymptomatic participants. Pressure pain thresholds (PPT) were obtained from eight locations around the knee joint to quantify pain sensitivity. A random forest classifier was utilized to identify KOA patients based on VAG signal features and PPTs. The most important features contributing to the classification accuracy were determined. The KOA patients participated in a second identical experimental session to examine the day-to-day reproducibility. MAIN RESULTS: The participants were classified with accuracy of 90%, 70%, 64% and 82% during over-ground gait, stairs descent, stairs ascent and sit to stand, respectively. However, the accuracy of the classifier was reduced by about 10%-25% due to a systematic bias in the extracted features across days. Features of the VAG signals in time and frequency domains as well as nonlinear features were found importantly contributing towards the classification accuracy. The VAG features extracted from the lateral side of the knee was found to be more informative than other locations. The classification based on PPT reached 77%. Medial and proximal knee PPT points contributed to the classification accuracy. SIGNIFICANCE: This study showed that using multichannel VAG signals to identify KOA patients allows better accuracy than the use of PPTs. However, VAG setup must be standardized to avoid day-to-day bias.

Wireless multichannel vibroarthrographic recordings for the assessment of knee osteoarthritis during three activities of daily living.

BACKGROUND: Variations in the internal pressure distribution applied to cartilage and synovial fluid explain the spatial dependencies of the knee vibroarthrographic signals. These spatial dependencies were assessed by multi-channel recordings during activities of daily living in patients with painful knee osteoarthrosis. METHODS: Knee vibroarthrographic signals were detected using eight miniature accelerometers, and vibroarthrographic maps were calculated for the most affected knee of 20 osteoarthritis patients and 20 asymptomatic participants during three activities: (i) sit to stand, (ii) stairs descent, and (iii) stairs ascent in real life conditions. Vibroarthrographic maps of average rectified value, variance of means squared, form factor, mean power frequency, % of recurrence and, % of determinism were obtained from the eight VAG recordings. FINDINGS: Higher average rectified value and lower % of recurrence were found in knee osteoarthritis patients compared with asymptomatic participants. All vibroarthrographic parameters, except for % of recurrence, differentiated the type of activity. Average rectified value, variance of means squared, form factor, and % of determinism were lowest while mean power frequency was highest during sit-to-stand compared with stairs ascent and descent. INTERPRETATION: Distinct topographical vibroarthrographic maps underlined that the computed parameters represent unique features. The present study demonstrated that wireless multichannel vibroarthrographic recordings and the associated topographical maps highlighted differences between (i) knee osteoarthritis patients and asymptomatic participants, (ii) sit to stand, stairs descent and ascent and (iii) knee locations. The technique offers new perspectives for biomechanical assessments of physical functions of the knee joint in ecological environment.

Knee joint vibroarthrography of asymptomatic subjects during loaded flexion-extension movements.

Vibroarthrography (VAG) has been proposed as a diagnostic tool for knee joint disorders. The methodological aspects of VAG assessments, such as sensor placement and outcomes measures have not been thoroughly investigated. The aim of this study was to investigate the effects of sensor placement and the effect of the knee extension and flexion movements using different added loads on six parameters extracted from VAGs of asymptomatic subjects. We hypothesized non-uniform distribution of VAGs during knee movement resulting from the underlying biomechanical features. Linear mixed model statistical analysis was carried out. Interpolation maps of the parameters were created to illustrate their spatial distribution over the knee joint. All parameters were significantly related to load, movement type, and location. There were significant load × movement type and location × movement type interaction for ARV and MPF, respectively. Further, the topographical maps of the six VAG parameters differed underlining the complementary information of the six VAG outcomes. The non-uniformity of the spatial distribution, movement type, and the knee joint load dependency of the investigate parameters open for new uses of VAG for joint diagnostic purposes including activities of daily living. Graphical abstract Visual summary of the main findings of the study. This figure shows that knee flexion-extension movement with various added external loads (0-1.25-2.5-5 kg) were investigated, vibroarthrogaphic (VAG) signals from eight locations over the knee were recorded, linear and nonlinear analyses were conducted revealing non-uniformity of the spatial distribution of the VAGs.

Trapezius viscoelastic properties are heterogeneously affected by eccentric exercise.

OBJECTIVES: The aim of this study was to investigate the influence of eccentric exercise (ECC) on the spatial mapping of muscle stiffness and creep of the upper trapezius, using a quantitative myotonometry device. DESIGN: Two groups of 16 subjects participated in the experimental sessions. In part A, the test-retest reliabilities of muscle stiffness and creep were assessed. In part B, muscle stiffness and muscle creep were mapped before, immediately after and 24h after ECC when post-exercise soreness had developed. METHODS: The ECC protocol consisted of 50 eccentric contractions divided into 5 bouts of 10 contractions at maximum force level. RESULTS: The relative reliabilities of stiffness and creep measurements were found to be substantial to almost perfect. Muscle stiffness for musculotendinous sites increased at 24h after ECC while it decreased for muscle belly immediately after and 24h after ECC. Muscle creep for musculotendinous sites decreased, and for muscle belly sites increased, immediately after and 24h after ECC. CONCLUSIONS: For the first time, the present study showed sign of discrepancies in the effects of ECC on muscle stiffness and creep, underlining opposite changes in the musculotendinous and muscle belly viscoelastic properties of upper trapezius.