Osteoarthritis

Mechanical Behavior and Failure of Scaffold Free Tissue Engineered Cartilage

Articular cartilage covers the articulating bones within synovial joints. It provides a bearing surface with low friction and wear properties. Although cartilage can function effectively for decades, it has limited ability to repair itself. Damage to articular cartilage is linked to degenerative diseases like Osteoarthritis (OA), which is a leading cause of disability in the United States. While severe cases of OA may be treated with a total joint replacement, tissue engineered (TE) cartilage is now emerging as a potential alternative treatment. TE constructs must function in the highly loaded environment of diarthrodial joints for many years. We have been investigating the mechanical behavior of tissue-engineered cartilage under combined compression and shear. Previous studies showed failure of TE cartilage under combined cyclic shear and static compressive loads, while native cartilage remained intact. Subsequent investigations identified a cell rich (matrix deficient) region in the middle layer of TE cartilage, which is sandwiched between matrix rich outer layers with lower cellularity. The objectives of this study are to determine the mechanical behavior of TE articular cartilage throughout its depth under static compressive and shear deformation. Failure under shear deformation, and the relationship between failure and the previously identified matrix deficient and matrix rich regions are of particular interest.


Listed In: Biomechanical Engineering, Biomechanics, Mechanical Engineering


The Effects of Total Ankle Replacement on Ankle Joint Mechanics During Walking

In the past ten years, the treatment of ankle Osteoarthritis (OA) has evolved from joint arthrodesis (bone fusion) procedures to a more advantageous total ankle replacement (TAR) in order to restore ankle joint function and alleviate pain. The purpose of this study was to examine the ankle joint function and mechanics during level walking in patients with ankle OA on the following two occasions: pre and 3-month post-surgery using the Salto Talaris Anatomic Ankle (STAA) TAR. Variables examined in this study were gait temporo-spatial parameters and ankle joint mechanics. Five subjects (3 males and 2 females; aged 61-73 years) all previously diagnosed with unilateral end-stage ankle OA performed level walking across two AMTI force platforms at a self-selected pace on the two specified occasions. Paired Student t-tests (p<0.05) were used to examine if the TAR system improved gait parameters and ankle joint mechanics after three months of surgery. All patients showed significant increases (P<0.05) in stride length and walking speed and a decrease in double support time three months post-surgery. In addition, patients exhibited an increase (P=0.039) in ankle power production and range of motion (P=0.045). It was found that the patients with the TAR joint demonstrated improved gait parameters and ankle joint mechanics during walking. These findings suggest that in as little as three months post-surgery, the STAA TAR helps patients regain ankle range of motion and strength.
Listed In: Biomechanics, Gait, Orthopedic Research