Coefficients of friction, lubricin, and cartilage damage in the anterior cruciate ligament‐deficient guinea pig knee

Abstract

The coefficient of friction (COF) of articular cartilage is thought to increase with osteoarthritis (OA) progression, and this increase may occur due to a decrease in lubricin concentration. The objectives of this study were to measure the COF of guinea pig tibiofemoral joints with different stages of OA and to establish relationships between COF, lubricin concentrations in synovial fluid, and degradation status using the Hartley guinea pig model. Both hind limbs from 24 animals were harvested: seven 3-month-old (no OA), seven 12-month-old (mild OA), and 10 that were euthanized at 12 months of age after undergoing unilateral ACL transection at 3 months of age (moderate OA). Contralateral knees served as age-matched controls. COFs of the tibiofemoral joints were measured using a pendulum apparatus. Synovial fluid lavages were analyzed to determine the concentration and integrity of lubricin using ELISA and Western blot, and the overall articular cartilage status was evaluated by histology. The results showed that the mean COF in the ACL-deficient knees was significantly greater than that of the no OA (p < 0.01) and mild OA knees (p < 0.01). Lubricin concentrations in the ACL-deficient knees were significantly lower than that in both of the other groups (p < 0.01). No significant differences in COF or lubricin concentration were found between the no OA and mild OA knees. Histology verified the extent of cartilage damage in each group. ß

Decreased lubricin concentrations and markers of joint inflammation in the synovial fluid of patients with anterior cruciate ligament injury

“…The decrease in SF lubricin concentrations following ACL injury has been corroborated in animal models. In the guinea pig, transection of the ACL led to significantly reduced SF lubricin levels 9 months after surgery, and this corresponded to an increase in the coefficient of friction of the articulating surfaces (19). Following rabbit ACL and posterior cruciate ligament (PCL) transection, SF lubricin concentrations in lavage fluid progressively decreased and lubricin was undetectable on Western blots, and this appeared to be associated with increased cartilage damage (20).…”

Human Synovial Lubricin Expresses Sialyl Lewis x Determinant and Has L-selectin Ligand Activity

“…RA patients varied with respect to lubricin expression, where the patients with low levels of lubricin had more aggressive joint disease (22). A relationship between the pathogenesis of OA and down-regulation of lubricin has been suggested in several animal models (23)(24)(25)(26). Furthermore, treatment of rat joints with injections of recombinant lubricin has indicated its protective effects on chondrocytes, suggesting the benefits of lubricating molecules as a possible therapy for OA (1,16).…”

A pendulum test as a tool to evaluate viscous friction parameters in the equine fetlock joint

“…Some studies have maintained conditions found within the joint to test the boundary lubricating ability of novel intra-articular treatments (Elsaid et al, 2005;Teeple et al, 2007Teeple et al, , 2008, although not SAPLs. There is even less information known about the properties of articular cartilage when the joint atmosphere is conserved and a joint viscous friction model used.…”