Articular cartilage deformation determined in an intact tibiofemoral joint by displacement‐encoded imaging

Abstract

This study demonstrates the in vitro displacement and strain of articular cartilage in a cyclically-compressed and intact joint using displacement-encoded imaging with stimulated echoes (DENSE) and fast spin echo (FSE). Deformation and strain fields exhibited complex and heterogeneous patterns. The displacements in the loading direction ranged from ؊1688 to ؊1481 m in the tibial cartilage and from ؊1601 to ؊764 m in the femoral cartilage. Corresponding strains ranged from ؊9.8% to 0.7% and from ؊4.3% to 0.0%. The displacement and strain precision were determined to be 65 m and less than 0.2%, respectively. Displacement-encoded magnetic resonance imaging is capable of determining the nonuniform displacements and strains in the articular cartilage of an intact joint to a high precision. Knowledge of these nonuniform strains is critical for the in situ characterization of normal and diseased tissue, as well as the comprehensive evaluation of repair constructs designed using regenerative medicine. Magn Reson Med 61:989 -993, 2009.

Probing articular cartilage damage and disease by quantitative magnetic resonance imaging

“…Therefore, depth-dependent characterization of cartilage mechanics is desirable (figure 3b). A direct non-invasive visualization of biomechanics considers the in situ loading environment [70] and the complex, depth-dependent mechanical behaviour of the tissue [66,71]. MRI techniques that can measure the internal deformation of articular cartilage can be used to visualize heterogeneous mechanical behaviour and also locate abnormal responses to applied loads.…”

“…Displacement encoding by stimulated echoes can be synchronized to cyclic loading [66,75] for the measurement of displacements under applied loading with MRI (dualMRI) in any MRI-visible biomaterial (figure 3b). DualMRI has been used to determine heterogeneous, depthdependent displacements and strains in cartilage explants [66] and intact cadaveric joints [70].…”

Displacement smoothing for the precise MRI-based measurement of strain in soft biological tissues

“…Another displacement-encoded MRI study that used a different imaging system showed that a MA filter improved displacement precision from 135 to 65 mm (Chan et al 2009). However, the error (both precision and bias) for other more advanced filtering techniques has not been determined.…”

Stress distributions and material properties determined in articular cartilage from MRI-based finite strains

“…Loading was applied to the joints via a double-acting pneumatic cylinder, computer-controlled by an electro-pneumatics system. A steady-state load-displacement response was considered to have been reached when the linearly time-regressed slope of pneumatic cylinder displacement per 10 s cycle fell below a criterion of half the spatial resolution divided by total imaging time, or 0.0163 mm/s with a total imaging time of 128 min (Chan et al, 2009a;Neu and Hull, 2003). For each joint, displacement-encoded phase data from a single sagittal slice through the medial tibiofemoral joint was acquired (3000 ms repetition time, 21.6 ms echo time, 256 Â 256 pixel matrix size, 64 Â 64 mm 2 field of view, 250 mm spatial resolution, 1.5 mm slice thickness).…”