Osteoarthritis means a pathological process characterized by dystrophy and degeneration of articular cartilage. As a rule, the issue is not limited to cartilage - later the pathology spreads to the (subchondral) bone tissue located below the cartilage. Therefore, osteoarthritis is also called osteoarthritis. And because all of these disorders eventually 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 or gonarthrosis is noted.
The essence of pathology
In terms of frequency and prevalence, osteoarthritis of the knee is second only to osteoarthritis of the hip joint (coxarthrosis). To understand what caused this, it is worth briefly looking at the characteristics of the anatomical structure of the knee and the functions 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. Thus, it is a complex joint formed by 2 joints - the patellofemoral and patellofemoral joints.
The joint surfaces of all 3 bones are covered with cartilage, which facilitates movement in the joint and protects 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. The articular cartilage does not have its own blood vessels. Its feeding is carried out diffusely by the intra-articular (synovial fluid). Like a sponge, cartilage shrinks under mechanical stress during movement, carrying heavy loads. At this point, the waste products are separated from the cartilage tissue into the surrounding synovial fluid. On the contrary, at the moment of relaxation, rest, the synovial fluid and the nutrients contained in it penetrate into the cartilage of the knee.
For a number of reasons, the nutrition of the articular cartilage of the knee joint is disrupted, leading to osteoarthritis of the knee. At the same time in the beginning there is a deficiency of nutrients in the cartilage tissue - chondroitin sulfate, glucosamine, calcium and other trace elements. Moisture is lost. This is a process of dystrophy, followed by degeneration - thinning of articular cartilage. In turn, these negative processes lead to structural and motor disorders in the knee joint.
Osteoarthritis of the knee is often confused with salt deposition. For example, some mineral salts, including table salt, are deposited in the form of microcrystals in the joint cavity, leading to pain and movement disorders. This is not true. Obviously, a completely different process for salt deposition is accepted. In response to the destruction of the articular cartilage in the subchondral bone, marginal bone growths - osteophytes - are formed to stabilize the knee at least to some extent. In the future, however, osteophytes only worsen osteoarthritis and contribute to the further destruction of cartilage.
Reasons
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, gonarthrosis can be primary or secondary. The mechanism of primary osteoarthritis is not fully understood. In this case, the disease is thought to be caused by a combination of factors, including:
- Old age, when degenerative changes occur not only in the articular cartilage, but also in all organs and tissues;
- Overweight, which increases the 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 altered;
- General metabolic disorders leading to a change in the mineral composition of synovial fluid.
Secondary osteoarthritis of the knee joints is a complication of other diseases. Most often such diseases are arthritis of various natures - gouty, rheumatic, rheumatoid, septic, tuberculous and others. In these diseases, various pathological factors (infection, distorted immune reactions, uric acid crystals) form 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 is a consequence of intra-articular fracture of the femur and tibia, hemarthrosis (hemorrhage in the joints), damage to the knee ligaments and menisci. Here the pathology is based on a mechanical factor (damage) and damage that develops after it (arthritis). In addition, osteoporosis is often accompanied by osteoarthritis. Calcium deficiency in bones leads to destruction not only of bone but also of cartilage tissue.
Symptoms
The main symptoms of osteoarthritis of the knee:
- Pain;
- Impaired knee movement;
- Difficulty walking;
- Cracking when moving;
- First - pathological tension, and then - muscle atrophy of the lower limb;
- Deformation of the knee joint.
In the beginning, as a rule, the patellofemoral joint suffers, which represents the majority of the functional load. In general, osteoarthritis of the knee is probably the most vulnerable. It is from the cartilage of the knee cap that dystrophic changes in osteoarthritis begin. Clinically, this is manifested by swelling and pain when touching 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 sac and ligament apparatus undergo sclerotic changes. The configuration of the joint changes. Initially, due to concomitant arthritis, it is swollen and inflamed. Subsequently, with the progression of degeneration and sclerosis, 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 muscles of the limb 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 these changes take shape over a long period of time. In this regard, there are 3 degrees of osteoarthritis:
- Osteoarthritis of the knee joint of the 1st degree. The pain is localized mainly in the area of the knee cap and on the inner surface of the knee joint. The pain is of a "starting" nature - it appears at the beginning of the movement, and then subsides. Also, the pain may appear with considerable effort (prolonged walking, carrying weights) and disappear after a break. At this stage there are no structural changes in the joint.
- Osteoarthritis of the knee becomes 2nd degree. The pain can appear even at rest and bother for a long time. Restrictions on the range of motion (contractures) appear in the knee. The patient is lame, he has to move with a stick. Inflammatory and dystrophic changes in the joint are formed, externally manifested with an increase in the knee due to edema.
- Osteoarthritis of the knee joint of 3rd degree. Severe knee pain that does not stop even after a long rest. Severe irreversible disorders in the structure of the joint, leading to ankylosis and loss of ability to move. A change in the configuration of the entire lower limb, manifested by its valgus or varus (O or X-shaped) curvature.
The diagnosis of osteoarthritis of the knee is made on the basis of the above symptoms and complaints of the patient, as well as X-ray data (narrowing of the joint space, osteophytes, osteoporosis, hardening of the bones). Gonarthrosis is treated comprehensively with drugs and physical procedures. In osteoarthritis of the 3rd degree, surgery is indicated, during which various types of knee plastic surgery are performed.