Special Issue on Biomechanical and Biomedical Factors of Knee Osteoarthritis

Knee osteoarthritis (OA) is a prevalent condition with up to 30–40% lifetime risk [1]. Despite general advancement in health science, modern lifestyle issues such as obesity have critically increased the OA population [2]. Until today, artificial joint replacement has been, however, considered the only cure, and in this sense, the knee joint can be viewed as a consumable that often does not warrant lifetime use. Symptomatic OA decreases quality of life, often accompanying frailty (e.g., sarcopenia and depression), injurious falls, and social segregation [3,4]. In addition to advancing surgical techniques and artificial joints, other fundamental solutions should be concurrently pursued to accommodate the ever-growing OA population, i.e., prevention and regeneration.

Prevention is something to prioritise first, but ironically, we tend to take it lightly until the issue becomes unneglectable. If this is, more or less, human nature, prevention strategies should take effect without conscious efforts. The first step for prevention is detecting and quantifying factors for OA to evaluate the risks and effectiveness of interventions [5,6]. OA can be defined as knee structure deformity due to excessive loads not tolerated by diminished articular cartilages, resulting in bone-to-bone collisions, micro-fractures, and pain. Therefore, the fundamental directions for OA prevention include reducing loads on the joint, strengthening surrounding tissues, correcting skeletal alignments, and enhancing cartilage regeneration.

Regeneration in the context of OA management can be referred to as the resynthesis of articular cartilage, which has long been considered impossible, but recent technological innovation in regenerative medicine has shed light on this ultimate Blackbox. Widely recognised in the general public as coronavirus vaccination, the manipulation of messenger ribonucleic acid (RNA) could trigger cellular metabolism to promote cartilage regeneration [7]. Similarly, stem cells will surely be most promising for future OA treatments that directly assist in the proliferation and strengthening of articular cartilage [8]. Although much is still to be discovered, it is quite safe to say that the regenerative approach will be one of the mainstream options for OA treatment [9]. Various methods are already available to enhance anabolic intracellular environments for articular cartilage resynthesis, such as electrical stimulus, magnetic field, infrared lighting, and ultrasound [10,11].

Along with joint replacement surgery, OA management is entering a new paradigm in which ‘prevention’ and ‘regeneration’ should be practically recommended. Pursuing the new paradigm defined here should take us closer to the absolute solution for OA, but continuous research efforts are essential. Scientific society should encourage and accept new attempts to establish the ultimate OA management concept, although it is needless to emphasise here again that conventional joint replacement surgery is currently the reliable cure for most of the OA population. The current Special Issue has collected a wide variety of research papers concerning the new paradigm of knee OA management and the latest advancements in conventional knee replacement surgery.