Critical‐size defect induces unicompartmental osteoarthritis in a stable ovine knee

Abstract

Animal models simulating osteoarthritis are frequently associated with irreversible changes in biomechanics. Although these models successfully induce osteoarthritis, results of experimental repair procedures are impaired by biomechanical problems. The aim of this study was to define the critical size of a chondral lesion to induce unicompartmental osteoarthritis in a stable joint. Sixteen sheep were randomly divided into four treatment groups. A cartilage defect (7-or 14-mm diameter) was created in the weight-bearing zone of the medial femoral condyle. The sheep were mobilized for 6 or 12 weeks. Osteoarthritis was determined by gross assessment, India ink staining, histology (Mankin score), and analysis of COMP in the serum. In the 6-week group, only minor osteoarthritis was registered for either defect size. After 12 weeks, the 14-mm defect induced minor osteoarthritis at the femoral condyle and caused significant degenerative changes at the tibial articular cartilage and the meniscus. The 7-mm defect created focal unicompartmental osteoarthritis at the medial femoral condyle and minor degenerative changes at the corresponding tibia. A 7-mm full-thickness chondral defect with a weight-bearing regimen of 12 weeks induced local osteoarthritis at the medial compartment in an otherwise stable joint as aimed. ß

Optimal Seeding Densities for In Vitro Chondrogenesis of Two- and Three-Dimensional-Isolated and -Expanded Bone Marrow-Derived Mesenchymal Stromal Stem Cells Within a Porous Collagen Scaffold

“…Sheep are routinely involved as animal models in cartilage engineering studies. 14,55,56 However, differences between species could impact the clinical applicability of our findings. Aspirates were derived from sheep at an age that is consistent with skeletal maturity and cartilage maturity based on zonal architecture, presence of a continuous calcified cartilage layer, and lack of spontaneous cartilage repair.…”

Chondrogenic Potential of Articular Chondrocytes Depends on Their Original Location

“…3,4 Several treatment modalities for focal cartilage defects are based on the use of autologous tissue or cells from areas in the affected joint that are not exposed to mechanical loading. The development and maturation of articular cartilage is directed by the influence of mechanical loading, 5,6 where physiological loading steers the metabolic activity of articular chondrocytes leading to a resistance of the cartilage to the loading patterns it is exposed to.…”

The Role of Environmental Factors in Regulating the Development of Cartilaginous Grafts Engineered Using Osteoarthritic Human Infrapatellar Fat Pad–Derived Stem Cells

“…1 This has led to increased interest in cell-based therapies for articular cartilage regeneration. Autologous chondrocyte implantation (ACI) has been used with reasonable success to treat focal lesions in the knee joint 2,3 ; however, it is still unclear whether ACI is superior to other treatment strategies.…”