Osteoarthritis refers to a pathological process that is characterized by dystrophy and degeneration of the articular cartilage. As a rule, the matter is not limited to only cartilage - later the pathology spreads to the (subchondral) bone tissue located under the cartilage. This is why osteoarthritis is also known as osteoarthritis. And since all of these diseases ultimately lead to a change in the structure of the joint, this process is called deforming osteoarthritis, which can affect any joint. In clinical practice, osteoarthritis of the knee or osteoarthritis of the knee is found in most cases.
The essence of pathology
In terms of frequency and prevalence, osteoarthritis of the knee is in second place after osteoarthritis of the hip (coxarthrosis). To find out what caused this, it is worthwhile to briefly consider the features of the anatomical structure of the knee and its functions. This is one of the most massive joints, the formation of which 3 bones are involved - femur, tibia and patella. So it is a complex joint that consists of 2 joints - the patellofemoral and the patellofemoral joint.
The joint surfaces of all 3 bones are covered with cartilage, which facilitates movement in the joint and protects the subchondral bone tissue from mechanical wear. In addition to the articular cartilage itself, the knee has menisci - paired cartilage formations that improve the congruence (anatomical correspondence) of the articular surfaces. Articular cartilage does not have its own blood vessels. Its nutrition takes place diffusely from the intra-articular (synovial fluid). Cartilage contracts like a sponge under mechanical stress during movement and carries heavy loads. At this point, waste products from the cartilage tissue are released into the surrounding synovial fluid. On the contrary, at the moment of relaxation, the synovial fluid and the nutrients it contains penetrate the knee cartilage.
For several reasons, the nutrition of the articular cartilage of the knee joint is disturbed, which leads to osteoarthritis of the knees. At the same time, there is initially a shortage of nutrients in the cartilage tissue - chondroitin sulfate, glucosamine, calcium and other microelements. Moisture is lost. This is a process of dystrophy, followed by degeneration - thinning of the articular cartilage. These negative processes in turn lead to structural and motor disorders in the knee joint.
Knee osteoarthritis is often confused with salt deposition. In other words, some mineral salts, including table salt, are deposited in the form of microcrystals in the joint cavity, which leads to pain and movement disorders. It is not so. Apparently a completely different process is used for the deposition of salts. In response to the destruction of the articular cartilage in the subchondral bone, marginal bone growths - osteophytes - are formed to at least partially stabilize the knee. In the future, however, osteophytes will only worsen the osteoarthritis and contribute to the further destruction of the cartilage.
causes
The causes of osteoarthritis of the knee joint are diverse and can be due to the pathology of the knee itself or other diseases and metabolic disorders. In this regard, osteoarthritis of the knee can be primary and secondary. The mechanism of primary osteoarthritis is not fully understood. It is believed that the disease in this case is caused by a combination of factors, including:
- Advanced age, when degenerative changes appear not only in the articular cartilage, but also in all organs and tissues;
- Excess weight, which increases the mechanical load on the joint;
- Physical inactivity or, conversely, excessive physical activity;
- Some congenital anatomical diseases of the knee in which the articular cartilage and subchondral bone are initially altered;
- General metabolic disorders that lead to a change in the mineral composition of the synovial fluid.
Secondary osteoarthritis of the knee joints is a complication of other diseases. The most common such diseases are arthritis of various kinds - gout, rheumatism, rheumatism, septic, tuberculosis, etc. In these diseases, various pathological factors (infection, perverse immune reactions, uric acid crystals) form an inflammation of the synovial membrane in the form of the so-called. Synovitis. Synovitis is inevitably accompanied by a deterioration in the quality of the synovial fluid, which in turn leads to osteoarthritis.
Another common cause of osteoarthritis is knee injuries. Post-traumatic osteoarthritis of the knee joint is a result of an intra-articular fracture of the femur and tibia, hemarthrosis (joint bleeding), damage to the knee ligaments and menisci. Here the pathology is based on a mechanical factor (damage) and damage that develops afterwards (arthritis). In addition, osteoporosis is often associated with osteoarthritis. Calcium deficiency in the bones leads to the destruction not only of bones, but also of cartilage tissue.
Symptoms
The main symptoms of osteoarthritis of the knee joint:
- Pains;
- Restricted knee movement;
- Difficulty walking;
- Crackling when moving;
- First - pathological tension, and then - muscular atrophy of the lower extremity;
- Misalignment of the knee joint.
In the beginning, the patellofemoral joint, which accounts for the largest part of the functional load, usually suffers. In general, knee pads with osteoarthritis are perhaps the most vulnerable. In osteoarthritis, dystrophic changes begin from the cartilage of the kneecap. Clinically, this manifests itself as swelling and pain when palpating this bone. As a result of dystrophic changes, the articular cartilage undergoes sclerotic changes - it loses its elasticity, is replaced by coarse connective tissue.
Subsequently, the joint pouch and the ligament apparatus suffer from sclerotic changes. The configuration of the joint changes. Initially, it is swollen and inflamed due to accompanying arthritis. Subsequently, as degeneration and sclerosis progresses, the amount of synovial fluid decreases sharply, the joint space narrows, which inevitably leads to movement disorders. At first the gait is difficult and the limb muscles are tense. Then ankylosis develops - complete immobility of the knee and, as a result, atrophy of the thigh and lower leg muscles. All of these changes take shape over a long period of time. In this regard, there are 3 degrees of osteoarthritis:
- Arthrosis of the knee joint 1st degree. The pain is mainly localized in the kneecap area and along the inner surface of the knee joint. The pain is "starting" in nature - it occurs at the beginning of the movement and then subsides. Pain can also occur with considerable exertion (long walking, carrying weights) and disappear after rest. There are no structural changes in the connection at this point.
- Arthrosis of the knee joint 2nd degree. The pain can also occur at rest and be a nuisance for a longer period of time. Movement restrictions (contractures) occur in the knee. The patient limps and has to move with a stick. Inflammatory and dystrophic changes are formed in the joint, which are externally manifested by an increase in the knee due to edema.
- Arthrosis of the knee joint 3rd degree. Severe knee pain that does not stop even after a long period of rest. Severe irreversible disorders of the joint structure leading to ankylosis and loss of mobility. Change in the configuration of the entire lower extremity, manifested by its valgus or varus curvature (O or X-shaped).
The diagnosis of knee osteoarthritis is based on the above-mentioned symptoms and complaints of the patient as well as X-ray data (narrowing of the joint space, osteophytes, osteoporosis, hardening of the bones). Osteoarthritis of the knee is treated in a complex with drugs and physical procedures. For 3rd degree osteoarthritis, surgical intervention is indicated in which various types of knee joint plastic surgery are performed.