Biomechanics of Instability and Its Relationship to OA

Joint instability is a known risk factor for osteoarthritis (OA), with aberrant biomechanics caused by acute injury or patient-related characteristics, such as increasing age, high body mass index, and altered motor patterns. Focusing on the knee as an example, the relationship between injury to joint structures, such as menisci, cruciate ligaments, collateral ligaments, and the development of OA, is reviewed. While the literature supports a causative role of instability in promoting and accelerating OA, the molecular mechanisms underlying instability-mediated joint degeneration must still be elucidated. Further limiting our understanding of the mechanistic role of instability in OA is heterogeneity in clinical studies, which often include patients with concomitant injuries (i.e. damage to more than one joint structure) and variation in treatments (e.g. operative vs non-operative), patient-related characteristics, and outcome metrics. Ongoing and future research with animal models, in vivo joint kinematics, and advanced imaging and biomarker analyses, promises improved understanding of the relationship between the biomechanics of instability and OA, in turn offering new treatment strategies.