Osteoarthritis is a pathological process characterized by dystrophy and degeneration of articular cartilage. As a rule, the matter is not limited to cartilage - later the pathology spreads to (subchondral) bone tissue located below the cartilage. Therefore, osteoarthritis is also called osteoarthritis. And since all of these disorders ultimately lead to a change in joint structure, this process is called deforming osteoarthritis, which can affect any joint. In clinical practice, arthrosis of the knee joint or gonarthrosis is recorded in most cases.
The essence of pathology
In terms of frequency and frequency, osteoarthritis of the knee is second only to 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 it performs. This is one of the most massive joints, in the formation of which 3 bones are involved - the femur, tibia and patella. So, it is a complex joint that consists of 2 joints - patellofemoral and patellofemoral joint.
The articular 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 is diffuse from intra-articular (synovial fluid). Like a sponge, cartilage shrinks under mechanical load during movement, carrying heavy loads. At this point, the waste products are released from the cartilage tissue into the surrounding synovial fluid. On the contrary, at the moment of relaxation, rest, the synovial fluid and nutrients that are in it penetrate the cartilage of the knee.
For several reasons, the nutrition of the articular cartilage of the knee joint is disturbed, which leads to arthrosis of the knee. At the same time, at first there is a lack 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 the articular cartilage. In turn, these negative processes lead to structural and motor disorders in the knee joint.
Knee osteoarthritis is often mistaken for salt deposition. For example, some mineral salts, including table salt, are deposited in the form of microcrystals in the joint cavity, which leads to pain and movement disorders. This is not true. Obviously a completely different salt deposition process is taken. 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 arthrosis and contribute to further destruction of cartilage.
Causes
The causes of osteoarthritis of the knee joint are diverse, and can be the result of pathology of the knee itself or other diseases and metabolic disorders. In this sense, gonarthrosis can be primary or secondary. The mechanism of primary arthrosis is not fully understood. It is believed that in this case the disease is caused by a combination of factors, including:
- In advanced age, when degenerative changes occur not only in the articular cartilage, but also in all organs and tissues;
- Excess weight, which increases mechanical stress on the joint;
- Physical inactivity, or conversely, 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 changes in the mineral composition of synovial fluid.
Secondary osteoarthritis of the knee joints is a complication of other diseases. The most common of such diseases are arthritis of various natures - gout, rheumatic, rheumatoid, septic, tuberculous, etc. In these diseases, various pathological factors (infections, distorted immune reactions, uric acid crystals) form inflammation of the synovial membrane in the form of the so-calledsynovitis. 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. Posttraumatic osteoarthritis of the knee joint is a consequence of intra-articular fracture of the femur and tibia, hemarthrosis (bleeding in the joint), damage to the ligaments of the knee and meniscus. Here, the pathology is based on a mechanical factor (damage) and the damage that develops after it (arthritis). In addition, osteoporosis is often accompanied by osteoarthritis. Lack of calcium in the bones leads to the destruction of not only the bones, but also the cartilage tissue.
Symptoms
The main symptoms of osteoarthritis of the knee:
- pain;
- Knee movement disorder;
- Difficulty walking;
- Cracking when moving;
- First - pathological tension, and then - atrophy of the muscles of the lower extremity;
- Knee joint deformity.
Initially, as a rule, the patellofemoral joint suffers, which makes up the largest part of the functional load. In general, knee pads with osteoarthritis are perhaps the most vulnerable. Dystrophic changes in arthrosis begin with the cartilage of the knee cap. Clinically, it is manifested by swelling and pain when feeling this bone. As a result of dystrophic changes, the articular cartilage undergoes sclerotic changes - it loses elasticity, it is replaced by coarse connective tissue.
Thereafter, the joint sac and ligament apparatus undergo sclerotic changes. The joint configuration changes. At the beginning, it was swollen and inflamed due to the accompanying arthritis. After that, 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 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 these changes take shape over a long period of time. In this regard, there are 3 degrees of osteoarthritis:
- Osteoarthritis of the knee joint 1st degree. The pain is localized mainly in the knee 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 subside. Also, the pain can occur with greater effort (long walks, carrying weights), and disappear after rest. There are no structural changes in the joint at this stage.
- Osteoarthritis of the knee joint 2nd degree. Pain can occur even at rest, and torment for a long time. Limits in range of motion (contractures) appear in the knee. The patient limps, must move with a cane. Inflammatory and dystrophic changes in the joint occur, which are manifested externally by enlargement of the knee due to edema.
- Osteoarthritis of the knee joint 3rd degree. Severe knee pain that does not stop even after a long rest. Severe irreversible disorders in the structure of the joint that lead to ankylosis and loss of ability to move. A change in the configuration of the entire lower extremity, manifested by its valgus or varus (O or X) curvature.
The diagnosis of knee osteoarthritis is made on the basis of 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). Gonarthrosis is treated complexly with the use of drugs and physical procedures. In arthrosis of the 3rd degree, surgical intervention is indicated, during which different types of knee joint plastic surgery are performed.