Intra-articular injection of hyaluronic acid based therapies is gaining popularity as a treatment option for non-operative
management of patients with symptomatic osteoarthritis. Although there is an abundance of evidence for both biological and
mechanical mechanisms of joint protection by hyaluronic acid, one clear intention of viscosupplementation is to reduce
friction and wear by providing an extrinsic lubricant. We tested the in vitro friction response of a novel hyaluronic acid
derivative that presents amphiphilic features to promote adhesion to the cartilage surface and thereby improve cartilage
Migrating Contact Area and Static Contact Area friction tests were conducted on bovine articular cartilage to assess the
efficacy of two lubricants, a chemically modified amphiphilic hyaluronic acid and synovial fluid from a healthy joint, as
well as a phosphate buffered saline negative control.
No differences in lubrication (P = 0.34) were evident between the three test articles during the Migrating Contact Area
test, which represents articulation of healthy articular cartilage.
The modified hyaluronic acid presented an equilibrium friction coefficient 2.8 times less than that of the synovial fluid
(P ≤ 0.0005) and five times less than that of the PBS control (P ≤ 0.0001) during the Static Contact Area test,
representing a mixed lubrication condition.
The present study demonstrated that a chemically modified amphiphilic hyaluronic acid can provide equivalent lubrication to
synovial fluid during articulation of loaded healthy articular cartilage and can provide superior lubrication as indicated
by a lower coefficient of friction than synovial fluid under loading conditions potentially associated with cartilage wear.