Softening of the Lateral Condyle Articular Cartilage in the Canine Knee Joint After Long Distance (up to 40 km/day) Running Training Lasting One Year

Abstract

The effects of long distance running training (up to 40km/day) on the biomechanical properties of young canine articular cartilage were investigated using in situ indentation creep technique. The stiffness of articular cartilage was determined in the form of instantaneous and equilibrium shear moduli. The rate of cartilage deformation was also computed. Microspectrophotometric and polarized light microscopic analyses were made for determination of local glycosaminoglycan content and collagen organization, respectively. During a period of one year, the runner dogs (n = 10) underwent a gradually increased treadmill exercise up to 40 km/day, while the littermate control dogs (n = 10) lived normally in their cages. The equilibrium shear modulus of articular cartilage decreased significantly by 12 to 14% (p < 0.05) in the lateral, but not in the medial, condyles of femur and tibia. In the lateral condyles of the runner dogs, the deformation rate of cartilage increased by 16% (p < 0.05). Consequently, the articular cartilage response to running training was site-dependent. The simultaneous changes of the equilibrium shear modulus or the retardation time spectrum and the glycosaminoglycan content confirm the key role of proteoglycans in modulating the cartilage equilibrium stiffness and creep rate. The changes in the instant shear modulus appeared to be predominantly related to the alterations in the organization of the superficial collagen network. Although the running training did not create cartilage damage, we assume that the softening of the cartilage may with time jeopardize the ability of articular cartilage to maintain its normal structural and functional properties.

Effects of increased chronic loading on articular cartilage material properties in the Lapine tibio-femoral joint

“…In a long-term canine study, no change in cartilage material properties or thickness resulted from lifelong exercise while animals wore weighted vests (Newton et al, 1997); whereas with increased running distance (≤40 km/day), decreases in GAG content and shear modulus were observed (Arokoski et al, 1993; Arokoski et al, 1994). These studies illustrate the sensitivity of AC to the magnitude and duration of loading.…”

Noncontact Evaluation of Articular Cartilage Degeneration Using a Novel Ultrasound Water Jet Indentation System

“…To perform the indentation on articular cartilage, a number of mechanical, arthroscopic and ultrasound indentation instruments have been developed. Mechanical indentation instruments can provide an accurate and repeatable indentation measurement, [6][7][8][9]33,37,49,51,62 but they are not convenient for clinical use. In addition, as mechanical instruments employ a needle probe to penetrate into the cartilage to measure the tissue thickness which is important information for the estimation of stiffness, destruction of the tissue structure might be caused.…”

Decreased birefringence of the superficial zone collagen network in the canine knee (stifle) articular cartilage after long distance running training, detected by quantitative polarised light microscopy.

“…16 17 The aim of the present study was to examine whether such long term running training also has any effects on the collagen fibril network of the articular cartilage. We used both conventional polarised light microscopy and a new quantitative computer based image analysis system attached to the polarised light microscope.…”