Validity of and recommendations for knee joint acoustic assessments during different movement conditions

Acute effects of a single bout of exercise therapy on knee acoustic emissions in patients with osteoarthritis: a double-blinded, randomized controlled crossover trial

BACKGROUND

Knee osteoarthritis is associated with higher kinetic friction in the knee joint, hence increased acoustic emissions during motion. Decreases in compressive load and improvements in movement quality might reduce this friction and, thus, sound amplitude. We investigated if an exercise treatment acutely affects knee joint sounds during different activities of daily life.

METHODS

Eighteen participants with knee osteoarthritis (aged 51.8 ± 7.3 years; 14 females) were included in this randomized crossover trial. A neuromuscular exercise intervention and a placebo laser needle acupuncture treatment were performed. Before and after both interventions, knee joint sounds were measured during three different activities of daily living (standing up/sitting down, walking, descending stairs) by means of vibroarthrography. The mean amplitude (dB) and the median power frequency (MPF, Hz) were assessed at the medial tibial plateau and the patella. Differences in knee acoustic emissions between placebo and exercise interventions were calculated by analyses of covariance.

RESULTS

Controlled for participant's age, knee demanding activity level and osteoarthritis stage, the conditions significantly differed in their impact on the MPF (mean(± SD) pre-post-differences standing up: placebo: 9.55(± 29.15) Hz/ exercise: 13.01(± 56.06) Hz, F = 4.9, p < 0.05) and the amplitude (standing up: placebo:0.75(± 1.43) dB/ exercise: 0.51(± 4.68) dB, F = 5.0, p < 0.05; sitting down: placebo: 0.07(± 1.21) dB/ exercise: -0.16(± .36) dB, F = 4.7, p < 0.05) at the tibia. There were no differences in the MPF and amplitude during walking and descending stairs (p > 0.05). At the patella, we found significant differences in the MPF during walking (placebo 0.08(± 1.42) Hz/ exercise: 15.76(± 64.25) Hz, F = 4.8, p < .05) and in the amplitude during descending stairs (placebo: 0.02 (± 2.72) dB/ exercise: -0.73(± 2.84) dB, F = 4.9, p < 0.05). There were no differences in standing up/ sitting down for both parameters, nor in descending stairs for the MPF and walking for the amplitude (p > 0.05).

CONCLUSION

The MPF pre-post differences of the exercise intervention were higher compared to the MPF pre-post differences of the placebo treatment. The amplitude pre-post differences were lower in the exercise intervention. In particular, the sound amplitude might be an indicator for therapy effects in persons with knee osteoarthritis.

TRIAL REGISTRATION

The study was retrospectively registered in the German Clinical Trials Register ( DRKS00022936 , date of registry: 26/08/2020).

Effect of warm-up and muscle fatiguing exercise on knee joint sounds in motion by vibroarthrography: A randomized crossover trial

Vibroarthrography measures joint sounds caused by sliding of the joint surfaces over each other. and can be affected by joint health, load and type of movement. Since both warm-up and muscle fatigue lead to local changes in the knee joint (e.g., temperature increase, lubrication of the joint, muscle activation), these may impact knee joint sounds. Therefore, this study investigates the effects of warm-up and muscle fatiguing exercise on knee joint sounds during an activity of daily living. Seventeen healthy, physically active volunteers (25.7 ± 2 years, 7 males) performed a control and an intervention session with a wash-out phase of one week. The control session consisted of sitting on a chair, while the intervention session contained a warm-up (walking on a treadmill) followed by a fatiguing exercise (modified sit-to-stand) protocol. Knee sounds were recorded by vibroarthrography (at the medial tibia plateau and at the patella) at three time points in each session during a sit-to-stand movement. The primary outcome was the mean signal amplitude (MSA, dB). Differences between sessions were determined by repeated measures ANOVA with intra-individual pre-post differences for the warm-up and for the muscle fatigue effect. We found a significant difference for MSA at the medial tibia plateau (intervention: mean 1.51 dB, standard deviation 2.51 dB; control: mean -1.28 dB, SD 2.61 dB; F = 9.5; p = .007; η² = .37) during extension (from sit to stand) after the warm-up. There was no significant difference for any parameter after the muscle fatiguing exercise (p > .05). The increase in MSA may mostly be explained by an increase in internal knee load and joint friction. However, neuromuscular changes may also have played a role. It appears that the muscle fatiguing exercise has no impact on knee joint sounds in young, active, symptom-free participants during sit to stand.