Electromechanical Assessment of Human Knee Articular Cartilage with Compression-Induced Streaming Potentials

Abstract

Purpose:To assess the electromechanical properties of human knee articular cartilage with compression-induced streaming potentials for reliability among users and correlation with macroscopic and histological evaluation tools and sulfated glycosaminoglycan (sGAG) content.Methods:Streaming potentials are induced in cartilage in response to loading when mobile positive ions in the interstitial fluid temporarily move away from negatively charged proteoglycans. Streaming potential integrals (SPIs) were measured with an indentation probe on femoral condyles of 10 human knee specimens according to a standardized location scheme. Interobserver reliability was measured using an interclass correlation coefficient (ICC). The learning curves of 3 observers were evaluated by regression analysis. At each SPI measurement location the degradation level of the tissue was determined by means of the International Cartilage Repair Society (ICRS) score, Mankin score, and sGAG content.Results:The computed ICC was 0.77 (0.70-0.83) indicating good to excellent linear agreement of SPI values among the 3 users. A significant positive linear correlation of the learning index values was observed for 2 of the 3 users. Statistically significant negative correlations between SPI and both ICRS and Mankin scores were observed (r = 0.502, P < 0.001, and r = 0.255, P = 0.02, respectively). No correlation was observed between SPI and sGAG content (r = 0.004, P = 0.973).Conclusions:SPI values may be used as a quantitative means of cartilage evaluation with sufficient reliability among users. Due to the significant learning curve, adequate training should be absolved before routine use of the technique.

Electromechanical properties of human osteoarthritic and asymptomatic articular cartilage are sensitive and early detectors of degeneration

“…Indeed, electromechanical QP and subchondral-bone plate thickness increased remarkably with degeneration, while cartilage thickness barely changed. These observations agree with previously published studies where the measured streaming potentials varied according to different early degeneration stages of cartilage 19,24,28 . Effectively, since cartilage alteration is characterized by enzymatically cleaved collagen network and a depletion of proteoglycan content e which leads to a biomechanical weakening of the tissue e lower streaming potentials are then generated during compression 24,26 .…”

“…Cartilage electromechanical properties were measured using a hand-held probe (Benchtop Arthro-BST, Biomomentum) 19,25,27,28 . This device allows a non-destructive measurement of streaming potentials generated during a light indentation (~1 s) of the articular cartilage with an array of 37 gold microelectrodes lying on a semi-spherical indenter (Ø ¼ 6.35 mm, 5 microelectrodes/mm 2 ).…”

“…Unfortunately, these grading systems provide qualitative and subjective diagnostics 17 . Furthermore, up to 50% of highly experienced orthopedists have stated that they felt a need for improvement in the differentiation between cartilage degeneration stages, more particularly in early degeneration corresponding to ICRS grade 0 to 2 17,19 . To overcome these limitations, a quantitative diagnostic device could be used.…”

Electromechanical probe and automated indentation maps are sensitive techniques in assessing early degenerated human articular cartilage

“…Moreover, the role of the camera‐registration system accompanying both systems is crucial since it registers the location of test measurements which in the case of the electromechanical probe allows for real‐time positioning and, in the case of the automated indentation technique, allows for mechanically controlled positioning over the surface. For clinical evaluation of cartilage, the electromechanical probe offers a major advantage over the automated indentation technique since it can be used as an arthroscopic tool and has already shown reliability in assessing the quality of cartilage and user‐independence . Nonetheless, the automated indentation technique has the advantage of being used on animals as small as rabbit or mice for in vitro studies …”

“…For clinical evaluation of cartilage, the electromechanical probe offers a major advantage over the automated indentation technique since it can be used as an arthroscopic tool and has already shown reliability in assessing the quality of cartilage and user-independence. 15,16,[41][42][43] Nonetheless, the automated indentation technique has the advantage of being used on animals as small as rabbit or mice for in vitro studies. 44 A limitation imposed by our study design is that our sensitivity analysis was based on macroscopic visual assessment (assumed comparable to the arthroscopic assessment) for delimiting all regions.…”