Arthrosis means a pathological process characterized by dystrophy and degeneration of the articular cartilage. As a rule, the issue is not limited to the cartilage alone - later the pathology spreads to the bone tissue (subchondral) located under the cartilage. Therefore, osteoarthritis is also called osteoarthritis. And since all these disorders eventually lead to a change in the structure of the joint, this process is called osteoarthritis deformans, which can affect any joint. In clinical practice, in most cases, arthrosis of the knee joint or gonarthrosis is observed.
the essence of pathology
In terms of frequency and prevalence, arthrosis of the knee is second only to arthrosis of the hip joint (coxarthrosis). To find out what caused this, it is worth looking briefly 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 articular surfaces of all 3 bones are covered by 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 paired meniscidal cartilage formations that increase the congruence (anatomical correspondence) of the articular surfaces. Articular cartilage has no blood vessels of its own. Its nutrition is performed diffusely from the intra-articular (synovial fluid). Like a sponge, cartilage contracts 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, during relaxation, at rest, the synovial fluid and the nutrients it contains penetrate into the cartilage of the knee.
For various reasons, the nutrition of the articular cartilage of the knee joint is disturbed, which leads to arthrosis of the knees. At the same time, initially, 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 the articular cartilage. These negative processes in turn lead to structural and motor disturbances in the knee joint.
Knee arthrosis is often confused with salt deposition. Let's say that some mineral salts, including table salt, are deposited in the form of microcrystals in the joint cavity, which causes pain and movement disorders. This is not true. Apparently, a completely different process is used for salt deposition. 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 aggravate arthrosis and contribute to further cartilage destruction.
Causes
The causes of arthrosis of the knee joint are diverse and may result from the pathology of the knee itself or from other diseases and metabolic disorders. In this sense, gonarthrosis can be primary and secondary. The mechanism of primary arthrosis 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 articular cartilage, but also in all organs and tissues;
- Excess weight, 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 altered;
- General metabolic disorders that lead to a change in the mineral composition of the synovial fluid.
Secondary arthrosis of the knee joints is a complication of other diseases. In most cases, these diseases are arthritis of various natures - gouty, rheumatic, rheumatoid, septic, tuberculous, etc. In these diseases, various pathological factors (infection, perverted immune reactions, uric acid crystals) form inflammation of the synovial membrane in the form of calls. synovitis. Synovitis is necessarily accompanied by a deterioration in the quality of synovial fluid, which in turn leads to arthrosis.
Another common cause of osteoarthritis is knee injuries. Posttraumatic arthrosis of the knee joint is a consequence of an intra-articular fracture of the femur and tibia, hemarthrosis (joint hemorrhage), injury to the knee ligaments and menisci. Here, the pathology is based on a mechanical factor (damage) and damage that develops after it (arthritis). Furthermore, osteoporosis is often accompanied by arthrosis. Calcium deficiency in bones leads to destruction not only of bone but also of cartilage tissue.
Symptoms
The main symptoms of arthrosis of the knee joint:
- Pain;
- Impaired knee movement;
- Difficulty in walking;
- Clicking when moving;
- First - pathological tension and then - lower limb muscle atrophy;
- Knee joint deformity.
In the beginning, as a rule, the patellofemoral joint suffers, which accounts for most of the functional load. In general, osteoarthritic knee braces are perhaps the most vulnerable. It is from the cartilage of the kneecap that dystrophic changes begin in arthrosis. Clinically, this manifests itself as swelling and pain upon feeling this bone. As a result of dystrophic changes, articular cartilage undergoes sclerotic changes - it loses its elasticity, is replaced by thick connective tissue.
Subsequently, the joint pouch and the ligament apparatus undergo sclerotic changes. The configuration of the joint changes. Initially, due to the concomitant arthritis, it is swollen, inflamed. Later, with the progression of degeneration and sclerosis, the amount of synovial fluid drastically decreases, 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 thigh and leg muscles. All of these changes take shape over time. In this regard, there are 3 degrees of arthrosis:
- Arthrosis of the 1st degree knee joint. The pain is mainly located in the area of the kneecap and along the inner surface of the knee joint. The pains are of an "initial" nature - they appear at the beginning of the movement and then subside. In addition, pain may appear with significant exertion (long walks, carrying weights) and disappear after rest. There are no structural changes to the joint at this stage.
- Arthrosis of the 2nd degree knee joint. Pain can occur even at rest and bother for a longer time. Limitations of range of motion (contractures) appear in the knee. The patient is limping, has to move with a cane. Inflammatory and dystrophic changes form in the joint, externally manifested by swelling of the knee.
- Arthrosis of the 3rd degree knee joint. Severe pain in the knee that does not stop even after a long rest. Severe irreversible disturbances in the joint structure, leading to ankylosis and loss of ability to move. Change in the configuration of the entire lower limb, manifested by its curvature in valgus or varus (in O or X).
The diagnosis of arthrosis of the knee is based on the above symptoms and the patient's complaints, as well as on X-ray data (narrowing of the joint space, osteophytes, osteoporosis, bone hardening). Goonarthrosis is treated in a complex way with the use of medications and physical procedures. In third-degree arthrosis, surgical intervention is indicated, during which various types of knee joint plastic surgery are performed.