Osteoarthritis implies a pathological process characterized by dystrophy and degeneration of the articular cartilage. As a rule, the issue is not limited to cartilage - later the pathology spreads to the bone (subchondral) tissue located below 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, osteoarthritis of the knee or gonarthrosis is observed in most cases.
The essence of pathology
In terms of frequency and prevalence, knee osteoarthritis is second only to hip osteoarthritis (coxarthrosis). To find out what caused this, it is worthwhile to dwell briefly on the features 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 are included 3 bones - femur, tibia and patella. Thus, it is a complex node formed by 2 nodes - patellofemoral and patellofemoral nodes.
The articular surfaces of all three bones are covered with cartilage, which facilitates movement in the joints and protects the subchondral bone tissue from mechanical wear. In addition to the articular cartilage itself, the knee has cartilaginous formations paired with menisci that increase the congruence (anatomical correspondence) of articular surfaces. The articular cartilage does not have its own blood vessels. Its feeding is carried out diffusely by intra-articular (synovial fluid). Like a sponge, cartilage shrinks under mechanical stress during movement, carrying heavy loads. At this point, waste products are released from the cartilage tissue into the surrounding synovial fluid. On the contrary, at the moment of relaxation, rest, synovial fluid and the nutrients it contains penetrate into the knee cartilage.
For a variety of reasons, the nutrition of the articular cartilage of the knee joint is disturbed, which leads to osteoarthritis of the knee. At the same time, in the beginning, there is a lack of nutrients in cartilage tissue - chondroitin sulfate, glucosamine, calcium and other trace elements. Moisture is lost. This is a process of dystrophy, followed by degeneration - thinning of the articular cartilage. On the other hand, these negative processes lead to structural and motor disorders in the knee joint.
Knee osteoarthritis is often confused with salt deposition. Let’s say, some mineral salts, including table salt, are deposited in the form of microcrystals in the articular cavity, which leads to 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 articular cartilage in the subchondral bone, marginal bone growths - osteophytes - are formed to stabilize the knee at least to some extent. However, in the future, osteophytes only worsen osteoarthritis and contribute to further cartilage destruction.
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, gonarthrosis can be primary and secondary. The mechanism of primary osteoarthritis is not fully understood. It is believed that in this case, the disease is caused by a combination of factors, including:
- Delayed 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 joints;
- 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 - gout, rheumatism, rheumatoid, septic, tuberculosis, etc. In these diseases, various pathological factors (infection, perverted immune reactions, uric acid crystals) form inflammation of the synovial membrane in the form of so-called. synoviti. 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 injury. Post-traumatic osteoarthritis of the knee is a consequence of an intra-articular fracture of the femur and tibia, hemarthrosis (joint hemorrhage), damage to the ligaments of the knee and meniscus. Here, the pathology is based on a mechanical factor (injury) and damage that develops after it (arthritis). In addition, osteoporosis is often associated with osteoarthritis. Lack of calcium in the bones leads to the destruction not only of bone but also of cartilage tissue.
Symptoms
The main symptoms of osteoarthritis of the knee joint:
- Pain;
- Impaired knee movement;
- Difficulty walking;
- Cracking while moving;
- First - pathological tension, and then - atrophy of the muscles of the lower limbs;
- Knee joint deformity.
In the beginning, as a rule, the patelofemoral joint suffers, which constitutes the largest part of the functional load. In general, osteoarthritis knee pads are 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 this bone is felt. As a result of dystrophic changes, the articular cartilage undergoes sclerotic changes - it loses its elasticity, is replaced by thick connective tissue.
Subsequently, the articular sac and ligament apparatus undergo sclerotic changes. The key 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 significantly, the joint space narrows, which inevitably leads to movement disorders. At first, walking is difficult and the limb muscles are tense. Ankylosis then 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 regard, there are 3 degrees of osteoarthritis:
- Osteoarthritis of the knee joint of the first degree. The pain is localized mainly in the area of the kneecap and along the inner surface of the knee joint. The pain is of an "initial" nature - it appears at the beginning of the movement, and then fades. Also, the pain may appear with considerable exertion (long walk, weight bearing) and disappear after rest. There are no structural changes in the joints at this stage.
- Osteoarthritis of the knee joint of the second degree. Pain can also occur at rest, and can bother for a longer time. Movement range restrictions (contractions) appear in the knee. The patient limps, has to move with the stick. Inflammatory and dystrophic changes are formed in the joints, manifested from the outside with an increase in the knee due to edema.
- Arthritis of the knee joint of the 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. Change in the configuration of the entire lower limb, manifested by its valgus or varus curvature (O or X-shaped).
The diagnosis of knee osteoarthritis 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, bone strengthening). Gonarthrosis is treated in a complex with the use of medication and physical procedures. Grade 3 osteoarthritis indicates surgical intervention during which different types of knee plastic surgery are performed.