Articular cartilage is a remarkable soft tissue that allows for near frictionless joint articulation and function throughout decades of loading cycles. Injury and disease cause alterations in the mechanical and biological environments within the joint, resulting in both articular cartilage tissue degeneration and changes in the lubricating function of the tissue and synovial fluid (chapter 1). To prevent the progression of articular cartilage degeneration and onset of the debilitating joint disease osteoarthritis (OA), early stage interventions aim to alter the mechanical environment and restore joint function.

Many open questions remain regarding the mechanical effect of early stage interventions on articular cartilage. In the first part of this dissertation, I explore the variability in lubricating function of synovial fluid from two distinct human arthritic populations and identify biomarkers that are characteristic of both lubricating function and response to viscosupplementation therapy (chapter 2). Together, these data identify a tribological endotype of arthritic patients and may give new insight into how biomarker expression can be used to inform treatment for arthritis patients.

In the remaining chapters of this thesis, I discuss current clinical evaluations of cartilage repair surgeries and assess factors that affect integrative repair. Developing successful strategies for the treatment of early OA requires a clear understanding of the anatomy and location of the chondral lesions (chapter 3). There are a variety of materials available to repair focal chondral defects, yet their ability to stimulate integrative repair is unclear. Fibrin sealants are commonly used to adhere or seal in repair treatments in a debrided defect, but it is unclear what effect source (autologous vs allogeneic) has on sealant mechanics or tissue repair (chapters 4 + 5). Across all repair treatments, histological evaluations are the gold standard for assessing the quality of repair. However, these histological assessments don’t provide information about the local strains the tissue experiences at the repair interface under loading. Both beneficial and damaging biological responses are intrinsically linked to mechanical loads in articular cartilage. As such, characterizing the local tissue strains provides a measure of integration strength and repair quality (chapter 6).

Collectively, this dissertation champions the utility of microscale mechanical analyses for identifying local effects of early stage osteoarthritis treatments on tissue mechanics, and in turn, answers larger questions pertaining to patient variability and surgical techniques in clinical practice. The techniques utilized here can be expanded upon to work towards optimizing the mechanical environment in the joint as a therapeutic mechanism for restoring joint function and retarding the progression of OA (chapter 7)