Biomechanics of knee osteoarthritis from local knee loading to whole kinetic chain imbalance: a narrative review

The onset and progression of knee osteoarthritis (KOA) are closely associated with abnormal mechanical loading. Previous research has focused largely on local biomechanical factors, such as lower-limb alignment and the knee adduction moment; however, these factors alone may not fully explain the discordance between radiographic degeneration and clinical manifestations such as pain and functional impairment. From a whole-kinetic-chain perspective, the knee functions as an intermediate link within the continuous spine-to-foot chain. Multisegmental malalignment involving the lumbar spine, pelvis, hip, and ankle-foot complex may shift the center of mass and alter the transmission of ground reaction forces, potentially interacting bidirectionally with local knee malalignment to redistribute joint loads and contribute to cartilage damage and pain. By examining the limitations of knee-centered biomechanical studies, we aim to synthesize evidence on the relationship between global alignment and KOA, explores how global-local load interactions may contribute to KOA progression, and proposes a conceptual framework in which the interplay between global and local malalignment may amplify mechano-inflammation and thereby promote disease progression. This review aims to provide new insights into biomechanical phenotyping, progression-risk assessment, and individualized mechanical interventions for KOA.