x-ray-with-neon-colors

Credit:www.freepik.com

KOA is caused by a biomechanical imbalance in the lower limb, which produces stress damage to the articular cartilage. Decreased muscle strength of the peripheral muscles of the knee joint and disturbed joint load conduction lead to an abnormal distribution of stress on the surface of the tibiofemoral joint and the patellofemoral joint, which is accompanied by articular motion that causes wear and tear of the articular cartilage, thus leading to the onset and progression of KOA. In addition, the pathological reaction caused by inflammatory mediators damages the articular cartilage and synovial membrane, which disrupts the mechanical balance of the knee joint. Inflammatory pain decreases the ability to exercise, which further leads to muscle wasting atrophy, and ultimately to the vicious circle of “pain - wasting”. Exercise therapy is the treatment of choice for KOA because it is effective in strengthening muscle strength, anti-inflammation and pain relief[1].

The main aerobic exercises in KOA are walking, swimming and aquatic exercise therapy, which are simple and easy to perform and highly accepted by patients. Voinier et al[2] found that walking was not associated with the structural progression of knee osteoarthritis and can be safely recommended for patients with KOA or those at risk of developing KOA. There are also few clinical studies on the treatment of KOA by swimming. Zhang et al[3] found that swimming could inhibit the caspase-3 expression level in OA and affect the apoptotic process of articular chondrocytes, thus improving the joint morphology. Compared with land-based exercise therapy, hydrotherapy is suitable for KOA patients because of its comfortable exercise environment, which can effectively reduce pain during exercise, relieve anxiety caused by the disease, and enhance the confidence as well as sense of well-being in exercise. Khruakhorn et al[4] found that in the short term (6 weeks), there was no significant difference in the effects of hydrotherapy and terrestrial exercise therapy, but in the 6-month follow-up, hydrotherapy was found to enhance the neuromuscular control and synergistic muscular contraction ability of patients with KOA, which can promote the dynamic balance of the body and walking coordination. It is worth noting that this study adopted the FITT principle based on the American college of sports medicine (ACSM) guidelines for exercise testing and prescription, which focuses on selecting the optimal frequency, intensity, and duration, and its exercise prescription can be well applied to clinical treatment.

Plyometric training has always been one of the core elements of physical therapy for KOA. Strengthening the muscle groups around the hip and knee joints can effectively relieve knee pain, strengthen the lower limbs and improve the level of movement of KOA patients. Muscle contraction can be categorized into isometric, isotonic and isokinetic contractions. It can also be classified as centripetal and centrifugal contractions according to the direction of movement. Isometric contraction is a static form of exercise, in which the muscle contraction generates force without any change in muscle length or joint movement, and is more suitable for patients with KOA and severe articular cartilage damage. Chinelo et al[5] found that isometric contraction training of quadriceps can effectively relieve knee pain and improve joint function in patients with KOA. It was also found that isometric training of quadriceps could increase the volume of patellar cartilage, which could help the repair of intra-articular soft tissues. Isotonic contraction refers to the muscle contraction process in which only the muscle length changes but the tension remains unchanged, accompanied by joint movement, so isotonic contraction training can strengthen the range of motion of the joint. Isometric contraction is also known as isokinetic contraction, i.e., the muscles contract with maximum force at a constant rate throughout the range of motion of the joint, and the force generated by the muscle contraction is always equal to the resistance. Compared to isotonic training, isokinetic training makes it easier to choose the intensity of exercise needed for treatment, and can be more efficient in improving muscle strength and relieving muscle soreness from exercise. Compared with isometric training, isokinetic training can effectively avoid the rapid increase of heart rate and blood pressure during exercise, which is suitable for elderly KOA patients.

Reference:

  1. Allen KD, Thoma LM, Golightly YM. Epidemiology of osteoarthritis. Osteoarthritis Cartilage. 2022 Feb;30(2):184-195.

  2. Voinier D, White DK. Walking, running, and recreational sports for knee osteoarthritis: An overview of the evidence. Eur J Rheumatol. 2022 Aug 9.

  3. Zhang J, Qi B, Liu M, Zhao T, Tan L. Influence of swimming exercise on the expression of apoptotic gene caspase-3 in chondrocytes in osteoarthritis. Am J Transl Res. 2021 Apr 15;13(4):2511-2517.

  4. Khruakhorn S, Chiwarakranon S. Effects of hydrotherapy and land-based exercise on mobility and quality of life in patients with knee osteoarthritis: a randomized control trial. J Phys Ther Sci. 2021 Apr;33(4):375-383.

  5. Onwunzo CN, Igwe SE, Umunnah JO, Uchenwoke CI, Ezugwu UA. Effects of Isometric Strengthening Exercises on Pain and Disability Among Patients With Knee Osteoarthritis. Cureus. 2021 Oct 22;13(10):e18972.