Chronic in vivo load alteration induces degenerative changes in the rat tibiofemoral joint

Abstract

Objective We investigated the relationship between the magnitude and duration of sustained compressive load alteration and the development of degenerative changes in the rat tibiofemoral joint. Methods A varus loading device was attached to the left hind limb of mature rats to apply increased compression to the medial compartment and decreased compression to the lateral compartment of the tibiofemoral joint of either 0% or 100% body weight for 0, 6 or 20 weeks. Compartment-specific assessment of the tibial plateaus included biomechanical measures (articular cartilage aggregate modulus, permeability and Poisson’s ratio, and subchondral bone modulus) and histological assessments (articular cartilage, calcified cartilage, and subchondral bone thicknesses, degenerative scoring parameters, and articular cartilage cellularity). Results Increased compression in the medial compartment produced significant degenerative changes consistent with the development of osteoarthritis including a progressive decrease in cartilage aggregate modulus (43% and 77% at 6 and 20 weeks), diminished cellularity (38% and 51% at 6 and 20 weeks), and increased histological degeneration. At 20 weeks, medial compartment articular cartilage thickness deceased 30% while subchondral bone thickness increased 32% and subchondral bone modulus increased 99%. Decreased compression in the lateral compartment increased calcified cartilage thickness, diminished region-specific subchondral bone thickness and revealed trends for reduced cellularity and decreased articular cartilage thickness at 20 weeks. Conclusions Altered chronic joint loading produced degenerative changes consistent with those observed clinically with the development of osteoarthritis and may replicate the slow development of non-traumatic osteoarthritis in which mechanical loads play a primary etiological role.

Obesity is associated with higher absolute tibiofemoral contact and muscle forces during gait with and without knee osteoarthritis

“…The higher compressive and shear loading associated with higher BMI category may be contributing to the accelerated development and progression of knee OA with higher BMI. Previous animal models have shown OA-like induced joint changes with direct application of increased non-physiologic compressive forces in rats (Roemhildt et al, 2013). As well, excessive shear force has been associated with biochemical changes to joint tissues that can initiative or progress degenerative pathways (Heiner et al, 2004;Sakai et al, 1999) .…”

Changes in in vitro compressive contact stress in the rat tibiofemoral joint with varus loading

“…The varus loads were applied using a previously developed varus loading device (VLD) (Fig. 1) (Roemhildt et al, 2010a,b; Roemhildt et al, 2012a,b). The VLD allows application of varus loadings to the tibiofemoral joint without disrupting the joint capsule while maintaining normal range of knee motion.…”

Insights into osteoarthritis progression revealed by analyses of both knee tibiofemoral compartments

“…Although the progression of osteoarthritis (OA) is generally currently unpredictable, altered biomechanical and biochemical properties of the joint organ facilitate progression of disease [1–4]. It is widely accepted that the molecular homeostasis of the joint depends on both the structural integrity of articular cartilage and the appropriate biomechanical stresses [5, 6].…”