Compressive fatigue and endurance of juvenile bovine articular cartilage explants

Medial knee cartilage is unlikely to withstand a lifetime of running without positive adaptation: a theoretical biomechanical model of failure phenomena

“…3), performing this kind of modeling is challenging with the paucity of data on cartilage fatigue in the literature. Riemenschneider et al (2019), published just last year, is the only published data on fatigue of cartilage in any animal in response to compressive loading. Several other studies examined fatigue of human hip and knee cartilage, but loaded strips of cartilage in tension along the collagen fibers (Weightman, Freeman & Swanson, 1973;Weightman, Chappell & Jenkins, 1978;Bellucci & Seedhom, 2001), which would require a much more complex model of cartilage mechanics to transform gait analysis data into collagen fiber strains.…”

“…Note that the triangles in Fig. 4 were ''runout'' samples from Riemenschneider et al (2019) that were undamaged at the testing limit of 100,000 loading cycles and were not included in the fitting process. The runout samples with the lower strain levels may represent the hypothetical ''endurance limit'' of the cartilage, where a ''lifetime'' of loading cycles can be sustained before failure.…”

“…The damage model does not explicitly include degradation of cartilage structure and material properties as functions of cumulative damage. These degradations are included implicitly in the Riemenschneider et al (2019) fatigue-life data the model is fit to.…”

Peer Review #1 of "Medial knee cartilage is unlikely to withstand a lifetime of running without positive adaptation: a theoretical biomechanical model of failure phenomena (v0.1)"

“…Similar evidence on joint loading and initiation of knee osteoarthritis is sparse but appears in observational studies on older adults (Amin et al, 2004;Lynn et al, 2007) and younger adults following knee surgery (Hall et al, 2015;Teng et al, 2017). Mechanical testing of articular cartilage explants suggests the fatigue life of cartilage is exhaustible within a number of loading cycles relevant to the human lifespan, at stress/strain levels well below the ultimate strength of the material (Weightman et al, 1973(Weightman et al, , 1978Chen et al, 1999;Bellucci & Seedhom, 2001;Sadeghi et al, 2017;Riemenschneider et al, 2019). These tests are performed on cartilage explants that cannot heal/repair, although cartilage is often considered to lack substantial capacity for natural healing given its lack of direct innervation and vascularization in a healthy state.…”

“…Values for and are determined by fitting a power law for cycles rather than time ( = , where is the cycles until failure) to data from Riemenschneider et al (2019). The fit to these data is presented in Fig.…”