Time, stress, and location dependent chondrocyte death and collagen damage in cyclically loaded articular cartilage

Abstract

We investigated the effect of light (0.1 MPa), moderate (1 MPa) or heavy ( 5 MPa) cyclical stresses applied continuously or intermittently for 0 to 72 h on cell death and collagen damage in adult bovine cartilage explants. No increase in cell death was observed in the cartilage loaded with a continuous cyclic stress at 0.1 MPa for up to 72 h. Cell death occurred in the uppermost superficial tangential zone (STZ) of explants after loading for 1 h at 1 MPa, and reached a maximum depth of 61 & 23 pm by 6 h (at the rate of 9 i 6 pmlh). At 5 MPa, cell death occurred in the STZ after as little as 1 min (30 cycles) of loading, and reached a maximum depth of 70 f 2 pm by 60 min (47 rt 8 pm/h). When an intermittent (with 2 s on, 2 s off) stress of 5 MPa was applied, cell death appeared in the STZ after 2 min (30 cycles) and increased to a depth of 63 f 2 pm at 60 min (45 i 11 pm/h). No significant differences were observed between the continuous and intermittent loading conditions. Both collagenase-cleaved and denatured collagen fibers were found in the STZ of explants loaded at 1 and 5 MPd. We concluded that load-induced cell death depends on load duration and magnitude, and that the chondrocytes in the STZ are more vulnerable to load-induced injury than those in the middle and deep zones.

How Do Hindfoot Fusions Affect Ankle Biomechanics: A Cadaver Model

“…However, our simplified model identified some predictable trends in ankle biomechanics during loading after hindfoot fusion. Despite the lack of increases in contact stress measurements seen in our study, altered ankle loading during dynamic activities warrant further investigation to complement these findings and to fully investigate the pathomechanics implicated in premature ankle degeneration after hindfoot arthrodesis [8,21,25]. Specifically, additional research is warranted to investigate the role of the medial and lateral gutters in load dissipation at the ankle after loss of hindfoot function.…”

“…Although successful subtalar joint arthrodesis provides pain relief, resultant alterations in ankle biomechanics need to be considered carefully given the possibility that this procedure may predispose the remaining hindfoot and ankle to accelerated degenerative changes [8,19,21,23,25]. The clinical association among subtalar joint arthrodesis, double (subtalar and talonavicular), and triple (subtalar, talonavicular, and calcaneocuboid) arthrodeses with progressive ankle degeneration is evident in medium-to long-term clinical studies [13,18,24].…”

Material Properties of Fresh Cold-stored Allografts for Osteochondral Defects at 1 Year

“…Multiple sections under various magnifications were obtained from the same sample. We (AR, CC) made subjective assessments on chondrocyte viability by the extent of surviving viable cell (green-fluorescent/highpower field), the location of chondrocyte loss relative to specific cartilage layers, and the growth pattern of chondrocyte repopulation such as cluster formations [13,40].…”

Increasing the Osmolarity of Joint Irrigation Solutions May Avoid Injury to Cartilage: A Pilot Study

“…The composition of irrigation solutions normally used in vivo during articular surgery is different. Articular cartilage is a complex, heterogenous, viscoelastic, anisotropic tissue in which the osmotic sensitivity of in situ chondrocytes varies depending on the composition of the extracellular medium [5,6,10,14,15,23,24]. Therefore, to determine whether varying the osmolarity of an extracellular medium is relevant clinically, it is essential to establish that the spatial distribution of chondrocyte death and the responses of in situ chondrocytes to mechanical injury following alterations in the extracellular osmolarity previously observed in experiments using standard culture media, can be reproduced using joint irrigation solutions normally used during open and arthroscopic articular surgery.…”