Water Content Of Articular Cartilage Research Articles

Use of a novel magnetically actuated compression system to study the temporal dynamics of axial and lateral strain in human osteochondral plugs

The high water content of articular cartilage allows this biphasic tissue to withstand large compressive loads through fluid pressurization. The system presented here, termed the “MagnaSquish”, provides new capabilities for quantifying the effect of rehydration on cartilage behavior during cyclic loading. An imbalanced rate of fluid exudation during load and fluid re-entry during recovery can lead to the accumulation of strain during successive loading cycles - a phenomenon known as ratcheting. Typical experimental systems for cartilage biomechanics use continuous contact between the platen and sample, which may affect tissue rehydration by compressing the top layer of cartilage and slowing fluid re-entry. To address this limitation, we developed a magnetically actuated device that provides full lift-off of the platen in between loading cycles. We investigated strain accumulation in cadaveric human osteochondral plugs during 750 loading cycles, with two dimensional profiles of the cartilage captured at 30 frames per second throughout loading and 10 min of additional free swelling recovery. Axial and lateral strain measurements were extracted from the tissue profiles using a UNet-based deep learning algorithm to circumvent manual tracing. We observed increased axial strain accumulation with shorter inter-cycle recovery, with static loading serving as the extreme case of zero recovery. The loading waveform during the 750 cycles dictated the pace of the recovery during the extended free swelling period, as shorter inter-cycle recovery led to more persistent axial strain accumulation for up to five minutes. This work showcases the importance of fluid re-entry in resisting strain accumulation during cyclical compression.

Degenerative changes through MR cartilage mapping in anterior cruciate ligament-reconstructed knees

BackgroundAnterior cruciate ligament (ACL) injury increases risk for post traumatic knee osteoarthritis. ACL injury causes lack of knee stability and frequently requires ACL-reconstruction (ACLR) in order to restore functional and anatomical joint stability. Magnetic resonance imaging with T2 mapping sequence is used to quantify the amount of water content in articular cartilage hence; it is considered a better tool and more beneficial than radiographic based assessment in early detection even before being symptomatic. The aim of work is to estimate the incidence of subclinical degenerative changes that happened early in patients who underwent ACL reconstruction and to identify the correlations of T2 mapping values with patients' BMI, meniscal state/operations, ACL graft assessment and presence of ACLR related complications.ResultsThe study was conducted upon 71 patients, divided into 61 anterior cruciate ligament reconstructed knees and 10 control cases using 1.5 T MRI. Assessment of cartilage sub-compartment T2 values and comparison with average normal cartilage T2 values obtained from the control group. Multiple correlations of the grade of articular cartilage degeneration within anterior cruciate ligament reconstructed knees with Body Mass Index (BMI), time of operation as well associated meniscal operations and anterior cruciate ligament graft complications.ConclusionsAdding the T2 cartilage mapping sequence improves the ability to detect subclinical early degenerative articular cartilage changes in patients who underwent anterior cruciate ligament reconstruction, taking into consideration the relation of the patients' BMI, previous meniscal injuries/operation, ACL graft status and related graft complications with the T2 cartilage mapping values.

Near Infrared Spectroscopic Evaluation of Water in Hyaline Cartilage

In diseased conditions of cartilage such as osteoarthritis, there is typically an increase in water content from the average normal of 60-85% to greater than 90%. As cartilage has very little capability for self-repair, methods of early detection of degeneration are required, and assessment of water could prove to be a useful diagnostic method. Current assessment methods are either destructive, time consuming, or have limited sensitivity. Here, we investigated the hypotheses that non-destructive near infrared spectroscopy (NIRS) of articular cartilage can be used to differentiate between free and bound water, and to quantitatively assess water content. The absorbances centered at 5200 and 6890cm(-1) were attributed to a combination of free and bound water, and to free water only, respectively. The integrated areas of both absorbance bands were found to correlate linearly with the absolute water content (R=0.87 and 0.86) and with percent water content (R=0.97 and 0.96) of the tissue. Partial least square models were also successfully developed and were used to predict water content, and percent free water. These data demonstrate that NIRS can be utilized to quantitatively determine water content in articular cartilage, and may aid in early detection of degenerative tissue changes in a laboratory setting, and with additional validations, possibly in a clinical setting.

Validation of Near Infrared Spectroscopy for Measurement of Water Content in Human Articular Cartilage Using Gelatin Model

This paper deals with the applicability of the near infrared (NIR) spectroscopy to quantitative measurement of the water content in human articular cartilage using gelatin model. We developed the device using NIR light at a wave length of 970nm, and investigated whether or not the device was useful for the measurement of the water content in articular cartilage. The gelatin was used as materials for the specimens with single, two- and three-layers. The absorbance defined as the intensity ratio between emitting and receiving NIR lights, the variation of receiving light intensity with the water content, and that with the distance between two probes of the light source and sensor were measured. The absorbance increased with increasing water content and with increasing probe distance (R 2 =0.86~0.91). In the layered specimens, the light was supposed to pass through the surface layer and then reach the adjacent layer. These results showed that the device was useful for the measurement of the water content in the single and layered specimens. This study suggested that the device developed in this study have some possibilities of acquiring the quantitative data of water content at any point from the surface of articular cartilage.

Assessment of interstitial water content of articular cartilage with T1 relaxation

The interstitial water content typically increases in the early degeneration of articular cartilage. Previously, T(2) relaxation has been related to water content, yet it is known to be strongly affected by the collagen orientation. Articular cartilage plugs from the bovine patella, femur and tibia (N=20) were mapped for T(1) and T(2) at 9.4 T to test the ability of T(1) relaxation to reflect cartilage water content. As a reference, water and proteoglycan (PG) contents were determined. Significant (P<.01) linear associations were demonstrated between the relaxation rates and tissue water content (R(1): r=-.81, R(2): r=-.60) and PG content (R(1): r=.75). After adjustment for the tissue water content, partial correlation analysis did not show significant associations between the relaxation rates and tissue PG content. After the effect of PGs was removed, significant (P<.05) linear correlation between the relaxation rates and tissue water content (R(1): r=-.48, R(2): r=-.50) was observed. Thus, the spin-lattice relaxation rate is proposed to provide a biomarker for water content in articular cartilage.

Correlation between the MR T2 value at 4.7 T and relative water content in articular cartilage in experimental osteoarthritis induced by ACL transection

Both animal and human studies using magnetic resonance imaging (MRI) show that cartilage degeneration increases the T2 value. However, it is unclear whether the T2 value correlates linearly with water content in cartilage with osteoarthritis. The purpose of this study was to investigate the relationship between the T2 value and water content using an animal model of cartilage injury measured at 4.7 T. Thirty Sprague Dawley rats were randomly separated into three groups (n=10 for each group). Group 1 rats were not operated on (control). Group 2 rats received a sham operation, and group 3 rats received an anterior cruciate ligament (ACL) transection. Six rats of each group were randomly assigned to T2 measurement and later subjected to ex vivo analysis of the relative water content of the knee cartilage. The other four rats in each group were killed, and the severity of cartilage degeneration was examined histologically. The knees of the six rats in the ACL transection group were imaged sequentially 4 and 13 weeks after ACL transection, and the relative water content was measured at 13 weeks. The cartilage T2 value was significantly higher 4 and 13 weeks after ACL transection in the operated knees than in the knees of the control and sham groups. The cartilage T2 value was significantly higher at 13 weeks than at 4 weeks in the operated knees. The T2 value was strongly positively correlated with the relative water content (R=0.885, P<0.0001). The trend of changes in the T2 values is consistent with an increase in the relative water content in our cartilage degeneration model. This model has potential use for the clinical evaluation of osteoarthritis.

OS7-2-6 Application of near infrared spectroscopy to determination of water content in articular cartilage

This paper deals with an application of the near infrared (NIR) spectroscopy to quantitative measurement of the water content in human articular cartilage under compressive loading and unloading. Indentation test on human articular cartilage, and the subsequent measurement of the NIR absorbance at the wave length of 1.46 μm have been performed. Difference in time dependent recovery of the NIR absorbance between the normal and degenerated articular cartilage were investigated. The degenerated articular cartilage showed relatively high Mankin (MK) score, an index of cartilage degeneration, and the rapid recovery of the NIR absorbance, while low MK score and slow recovery of the NIR absorbance were observed in the normal articular cartilage. The relations between the NIR absorbance and water content, the NIR absorbance and thickness, and the NIR absorbance and water content per unit thickness were established. The cartilage showed no correlation between the NIR absorbance and water content, but showed the NIR absorbance was in proportion to water content per unit cartilage thickness. Linear relation between thickness and the NIR absorbance was found as well. From these results, water content in human articular cartilage was able to be formulated as a function of the NIR absorbance. It is concluded that non-destructive, low-invasive and quantitative estimation of water content in human articular cartilage can be performed using the NIR spectroscopy.

1132 近赤外線水分計を用いた軟骨含水量の測定(第2報) : 正常関節軟骨の検量線作成(S11-2 計測と力学-生体への応用(2),S11 計測と力学-生体への応用)

1132 近赤外線水分計を用いた軟骨含水量の測定(第2報) : 正常関節軟骨の検量線作成(S11-2 計測と力学-生体への応用(2),S11 計測と力学-生体への応用)

Evaluation of water content by spatially resolved transverse relaxation times of human articular cartilage

Non-invasive assessment of cartilage properties, specifically water content, could prove helpful in the diagnosis of early degenerative joint diseases. Transverse relaxation times T2 of human articular cartilage (34 cartilage slices of three donors) were measured on a pixel-by-pixel basis in a clinical whole body MR system in vitro. In vivo feasibility to measure quantitative T2 maps was shown for human patellar cartilage. The relaxation times of cartilage with collagen in the radial zone oriented perpendicular to the magnetic field increased from approximately 10 ms near the bone to approximately 60 ms near the articular surface. Cartilage water content of the tibial plateau and femoral condyles could be determined from the correlation with T2 (R2 = 0.71) with an error of approximately 2 wt.%. In vivo, directional variation would need to be considered. If confirmed in vivo, T2 measurements could potentially serve as a non-invasive tool for the evaluation of the status and distribution of water content in articular cartilage.