Arthrosis means a pathological process characterized by dystrophy and degeneration of the articular cartilage. As a rule, the matter is not limited to cartilage alone - later the pathology spreads to the (subchondral) bone tissue located under the cartilage. Therefore, arthrosis is also called osteoarthritis. And since all 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 arthrosis of the knee joint or gonarthrosis is noted.
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 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. Thus, it is a complex joint formed by 2 joints - the patellofemoral and patellofemoral joints.
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 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 moment, 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 contained in it penetrate into the knee cartilage.
For a number of reasons, the nutrition of the articular cartilage of the knee joint is disturbed, which entails arthrosis 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.
Knee arthrosis is often mistaken for salt deposition. Allegedly, 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 the articular cartilage in the subchondral bone, marginal bone growths - osteophytes - are formed in order to stabilize the knee at least to some extent. However, in the future, osteophytes only aggravate arthrosis, and contribute to further destruction of cartilage.
Causes
The causes of arthrosis of the knee joint are diverse, and may 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 arthrosis is not fully understood. It is believed that in this case, the disease is 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 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 the synovial fluid.
Secondary arthrosis 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 inflammation of the synovial membrane in the form of the so-called. synovitis. Synovitis is necessarily accompanied by a deterioration in the quality of synovial fluid, which, in turn, leads to arthrosis.
Another common cause of arthrosis is knee injuries. Post-traumatic arthrosis of the knee joint is a consequence of 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 damage that develops after it (arthritis). In addition, osteoporosis is often accompanied by arthrosis. Calcium deficiency in bones entails the destruction of not only bone, but also cartilage tissue.
Symptoms
The main symptoms of arthrosis of the knee joint:
- Pain;
- Impaired knee movement;
- Difficulty walking;
- Crunch when moving;
- First - pathological tension, and then - muscle atrophy of the lower limb;
- Deformity of the knee joint.
In the beginning, as a rule, the patellofemoral joint suffers, which accounts for most of the functional load. In general, knee pads with arthrosis are perhaps the most vulnerable. It is from the cartilage of the kneecap that dystrophic changes begin in arthrosis. Clinically, this is manifested by swelling and pain when feeling 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 articular bag and the ligamentous apparatus undergo sclerotic changes. The configuration of the joint changes. Initially, due to concomitant arthritis, it is swollen, 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 arthrosis:
- Arthrosis of the knee joint of the 1st degree. The pains are localized mainly in the area of the kneecap and along the inner surface of the knee joint. The pains are of a "starting" nature - they appear at the beginning of the movement, and then subside. Also, pain can appear with significant exertion (long walking, carrying weights), and disappear after rest. There are no structural changes in the joint at this stage.
- Arthrosis of the knee joint of the 2nd degree. The 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 around with a stick. Inflammatory and dystrophic changes in the joint are formed, externally manifested by an increase in the knee due to edema.
- Arthrosis of the knee joint of the 3rd degree. Severe knee pain that does not stop even after long rest. Severe irreversible disturbances in the structure of the joint, leading to ankylosis and loss of the ability to move. Change in the configuration of the entire lower limb, manifested by its valgus or varus (O or X-shaped) curvature.
Diagnosis of knee arthrosis is carried out 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 hardening). Gonarthrosis is treated in a complex with the use of medicines and physical procedures. With arthrosis of the 3rd degree, surgical intervention is indicated, during which various types of knee joint plastic are performed.