The effect of detachment of the articular cartilage from its calcified zone on the cartilage microstructure, assessed by ²H‐spectroscopic double quantum filtered MRI

Abstract

Most studies on articular cartilage properties have been conducted after detachment of the cartilage from the bone. In the present work we investigated the effect of detachment on collagen fiber architecture. We used one-dimensional 2H double quantum filtered MRI on cartilage bone plugs equilibrated in deuterated saline. The quadrupolar splittings observed in the different zones were related to the degree of order and the density of the collagen fibers. The method is non-destructive, allowing for measurements on the same plug without the need for fixation, dehydration, sectioning and decalcification. Detachment of the radial from the calcified zone resulted in swelling of the cartilage plug in physiological saline and a concomitant decrease in the quadrupolar splitting. The effect of mechanical pressure on the 'H quadrupolar splittings for the detached cartilage and for the calcified zone-bone plugs were compared with those of the same zones in the intact cartilage-bone plug. The splitting in the radial zone of the detached cartilage collapsed at much smaller loads compared to the intact cartilage-bone plug. The effect of the load on the size of the cartilage was also greater for the detached plug. These results indicate that anchoring of the cartilage to the bone through the calcified zone plays an important role in retaining the order of the collagen fibers. The water 2H quadrupolar splitting in intact and proteoglycan-depleted cartilage was the same, indicating that the proteoglycans d o not contribute to the ordering of the collagen fibers.

Multinuclear NMR and microscopic MRI studies of the articular cartilage nanostructure

“…Pressure was applied from the bone side by the weights. From Keinan-Adamsky et al (39) cartilage, a gradual change in the residual quadrupolar splittings in the various zones is observed. The results of such an experiment are shown in Fig.…”

“…In the SQ-QE pulse sequence, in order to avoid the cancellation of the effect of the phase encoding gradients as a result of the choice of coherence pathway, the gradients are employed with the same magnitude and an opposite sign. The optimal value of q is 908 for I ¼ 1 nuclei and 70.58 for I ¼ 3/2 nuclei from Keinan-Adamsky et al, with kind permission of Springer Science and Business Media (40) 2 H 1D DQF spectroscopic MRI was used to study the effect of mechanical load on the collagen fibers architecture (38,39). In the later study (39), we used a laboratory-built pressure device (Fig.…”

“…We applied the same 2 H DQF techniques to study the effect of detachment of the cartilage from the bone on the collagen matrix architecture (39). In the experiment, 1D 2 H DQF spectroscopic imaging was first performed on a cartilage bone plug.…”

The effect of decalcification on the microstructure of articular cartilage assessed by 2H double quantum filtered spectroscopic MRI

“…9. Eliav U, Navon G (1999) A study of dipolar interactions and dynamic processes of water molecules in tendon by 1 …”

“…It is mainly composed of a solid matrix of collagen fibers, proteoglycans, and water. The importance of the attachment of cartilage to its underlying bone in retaining the collagen matrix architecture has been previously emphasized [1]. The collagen fibers are anchored within the calcified zone, and are oriented perpendicular to the bone surface.…”