Osteoarthritis means a pathological process characterized by dystrophy and degeneration of the articular cartilage. As a general rule, the matter is not limited only to cartilage; then the pathology spreads to the bone tissue (subchondral) located under the cartilage. Therefore, osteoarthritis is also called osteoarthritis. And since all of these disorders 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, in most cases osteoarthritis of the knee joint or gonarthrosis is observed.
The essence of pathology.
In terms of frequency and prevalence, osteoarthritis of the knee ranks second after osteoarthritis of the hip joint (coxarthrosis). To find out what caused this, it is worth briefly dwelling on the features of the anatomical structure of the knee and the functions that it performs. This is one of the most massive joints, in the formation of which 3 bones are involved: the femur, the tibia and the patella. Therefore, it is a complex joint made up of 2 joints: the patellofemoral and patellofemoral joints.
The articular surfaces of the 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 cartilaginous formations that enhance the congruence (anatomical correspondence) of the articular surfaces. Articular cartilage does not have its own blood vessels. Its nutrition is carried out diffusely from the intra-articular (synovial fluid). Like a sponge, cartilage contracts under mechanical stress during movement, carrying heavy loads. At this time, waste products are released from the cartilaginous tissue into the surrounding synovial fluid. On the contrary, at the moment of relaxation, rest, the synovial fluid and the nutrients it contains penetrate the cartilage of the knee.
For various reasons, the nutrition of the articular cartilage of the knee joint is disturbed, leading to osteoarthritis of the knees. At the same time, at first, there is a deficiency 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. In turn, these negative processes lead to structural and motor disorders in the knee joint.
Osteoarthritis of the knee is often mistaken for salt deposition. Let's say that some mineral salts, including table salt, are deposited in the form of microcrystals in the joint cavity, causing pain and movement disorders. This is not true. Apparently, a completely different process is taken for the deposition of salts. In response to the destruction of the articular cartilage in the subchondral bone, marginal bony growths (osteophytes) form to stabilize the knee at least to some extent. However, in the future, osteophytes will only aggravate osteoarthritis and contribute to further destruction of 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 sense, gonarthrosis can be primary and secondary. The mechanism of primary osteoarthritis is not fully understood. In this case, the disease is believed to be caused by a combination of factors, including:
- Advanced age, when degenerative changes occur not only in the articular cartilage, but also in all organs and tissues;
- Overweight, which increases mechanical stress on the joint;
- Physical inactivity, or vice versa, excessive physical activity;
- Some congenital anatomical disorders of the knee, in which the articular cartilage and subchondral bone are initially disturbed;
- General metabolic disorders leading to a change in the mineral composition of the synovial fluid.
Secondary osteoarthritis of the knee joints is a complication of other diseases. Most often, such diseases are arthritis of various nature: gouty, rheumatic, rheumatoid, septic, tuberculous, etc. In these diseases, various pathological factors (infection, perverted immune reactions, uric acid crystals) form an inflammation of the synovial membrane in the form of so-called. synovitis. Synovitis is necessarily accompanied by a deterioration in the quality of synovial fluid, which, in turn, leads to osteoarthritis.
Another common cause of osteoarthritis is knee injuries. Post-traumatic osteoarthritis of the knee joint results from an intra-articular fracture of the femur and tibia, hemarthrosis (joint hemorrhage), damage to the knee ligaments and menisci. Here, the pathology is based on a mechanical factor (damage) and the damage that develops afterwards (arthritis). In addition, osteoporosis is often accompanied by osteoarthritis. Calcium deficiency in the bones involves the destruction not only of the bone, but also of the cartilage tissue.
Symptoms
The main symptoms of osteoarthritis of the knee joint:
- Pain;
- Altered knee movement;
- Dificulty to walk;
- Cracking when moving;
- First - pathological tension, and then - muscular atrophy of the lower limb;
- Deformity of the knee joint.
At first, as a general rule, the patellofemoral joint suffers, which accounts for most of the functional load. In general, knee braces with osteoarthritis are perhaps the most vulnerable. It is from the cartilage of the patella that the dystrophic changes in osteoarthritis begin. Clinically, this is manifested by swelling and pain when palpating this bone. As a result of dystrophic changes, the articular cartilage undergoes sclerotic changes: it loses its elasticity and is replaced by thick connective tissue.
Later, the articular bag and the ligamentous apparatus undergo sclerotic changes. The joint configuration changes. Initially, due to concomitant arthritis, it is swollen, inflamed. Subsequently, with the progression of degeneration and sclerosis, the amount of synovial fluid decreases dramatically, 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 muscles of the thigh and lower leg. All of these changes take shape over a long period of time. In this sense, there are 3 degrees of osteoarthritis:
- Osteoarthritis of the knee joint of the 1st degree. The pains are mainly localized in the patella area and along the inner surface of the knee joint. The pains are "initial" in nature: they appear at the beginning of the movement and then disappear. Also, the pain can appear with significant effort (walking a lot, lifting weights) and disappear after rest. There are no structural changes in the joint at this stage.
- Osteoarthritis of the knee joint of the second degree. Pain can occur even at rest and bother for a longer time. Range of motion limitations (contractures) appear in the knee. The patient limps, he has to move with a cane. Inflammatory and dystrophic changes are formed in the joint, which are externally manifested by an increase in the knee due to edema.
- Osteoarthritis of the knee joint of the third degree. Severe knee pain that doesn't stop even after a long rest. Serious and irreversible alterations in the structure of the joint, causing ankylosis and loss of movement capacity. Change in the configuration of the entire lower limb, manifested by its curvature in valgus or varus (in the form of O or X).
Diagnosis of knee osteoarthritis is made on the basis of the patient's previous symptoms and complaints, as well as X-ray data (joint space narrowing, osteophytes, osteoporosis, bone hardening). Gonarthrosis is treated in a complex with the use of drugs and physical procedures. With third-degree osteoarthritis, surgical intervention is indicated, during which various types of plastic are made for the knee joint.