The Detection of Knee Joint Sounds under Different Loading Conditions using Vibroarthrography

Abstract

Crepitus of the knee may mirror structural changes of the joint during motion. Although the magnitude of these sounds increases with greater cartilage damage, it is unclear whether knee joint sounds also reflect joint loading. PURPOSE: To reveal whether the magnitude of knee joint sounds differs across defined dynamic loading conditions using vibroarthrography. METHODS: Twelve healthy volunteers (26 ± 3.59 years, 7 females) participated in the randomized-balanced crossover study. Knee joint sounds were recorded (linear sampling, 5512 Hz) by means of two acoustic sensors (microphones), one placed on the medial tibial plateau and one on the patella. Two activities of daily life (standing up from and sitting down on a bench; descending stairs) and three open kinetic chain (OKC) knee extension-flexion cycles (passive movement, 10 % and 40 % loading of the individual one repetition maximum) were performed. Each participant carried out three sets of five repetitions and three sets of 15 steps downwards (stairs), respectively. For data analysis, the mean noise volume for each loading condition was determined. The resulting values were expressed as relative difference to the individual OKC passive movement value. Friedman test and Bonferroni-Holm adjusted post-hoc test were performed to detect differences between conditions. RESULTS: The OKC passive movement sound ranged from .0001 to .003 a.u. (≙ 43.6 - 69.3 dB) at the medial tibia and from .001 to .03 a.u. (≙ 60.6 - 87.7 dB) at the patella. Significant differences between joint sound amplitudes for all movements, both measured at the medial tibial plateau (Chi2=20.7, p<0.001) and at the patella (Chi2=27.6, p<0.001) were obtained. The corresponding median differences for the tibia sensor were: stand/sit: 236 %, stairs: 675 %, OKC10: 291 %, OKC40: 384 %; and for the patella sensor: stand/sit: 158 %, stairs: 260 %, OKC10: 75 %, OKC40: 78 %. CONCLUSION: Overall, the larger the supposed knee joint loading was, the louder was the recorded knee crepitus. Consequently, vibroarthrographically assessed knee joint sounds can differ across knee joint loading conditions. Future studies should further support these findings using inverse dynamics as a measurement of knee joint loading.