Although patellofemoral osteoarthritis is common and a frequent cause of disability, its aetiology remains unknown. Biomechanical factors are believed to be important in the pathogenesis of the disease. Although the patellofemoral joint bears little axial load during normal walking, retropatellar load increases during knee flexion and can exceed three times body-weight during deep knee bends. The combination of large forces being transmitted to relatively incongruent articular surfaces during activities of daily living may explain why patellofemoral osteoarthritis is so common. Other patellofemoral pathologies considered to be biomechanically mediated, such as patellofemoral pain syndrome, may provide clues to helping understand the aetiology of patellofemoral osteoarthritis. For instance, patellofemoral pain syndrome is believed to be primarily due to abnormalities in bony geometry, neuromuscular patterns and tight fibromuscular support, which ultimately contribute toward lateral patella translation, maltracking and pain. Genu valgum has also been implicated as a factor that predates lateral patella pathologies, such as the progression of patellofemoral osteoarthritis. Nevertheless, it remains unclear whether common patellofemoral pathologies that occur in early life, such as subluxation/ dislocation and patellofemoral pain syndrome, are risk factors for degenerative changes, such as patellofemoral osteoarthritis, that occur in later life. This review examines the biomechanical factors associated with patellofemoral joint pathology, using patellofemoral osteoarthritis as a disease paradigm.