Total endoprosthesis of the knee joint

Total knee arthroplasty, also known as arthroplasty or alloplasty, is an operation in which the whole joint or part of it is replaced. ' foreign material. The goal of total knee arthroplasty is to restore the anatomical axis of the lower limb, ensure the stability of the joint, improve the function of the limb and, above all, eliminate pain.

This is one of the most frequent and effective operations performed here. It was put into practice in the 1980s after the successful development of total endoprostheses hip joint. Patients suffering from pain, which makes them uncomfortable or even impossible to move, usually feel a significant relief after the operation and return to an active life.

Development
The total endoprosthesis of the knee joint underwent many years of development. The first hinge endoprosthesis was constructed, which did not respect the physiological movement in the knee and therefore loosened soon. Endoprostheses were also created that replaced only part of the joint, e.g. a unicompartmental endoprosthesis replacing the medial or lateral part of the knee joint. In the USA, mobile implants were developed that reduced the stress forces acting on the implant at the point of contact with the bone and thus guaranteed a longer life of the endoprosthesis.

Most of today's endoprostheses are based on a modular system - metal femoral components and tibial polyethylene inserts embedded in a metal tibial anchor are used. Ceramic femoral components are also used to reduce polyethylene wear. The lifespan of an endoprosthesis is individual, but usually exceeds 10 years. New materials are constantly being sought to extend the service life even further.

Metal implants can be "cemented" or "cementless" with special surfaces. Most implants include also a replacement for the patella'. In the Czech Republic, a total endoprosthesis was developed by Prof. Rybka and doc. Vavřík in cooperation with Walter-Motorlet, it was first implanted in 1984.

Indication
Indications for a total endoprosthesis are situations where the function of the joint is "significantly impaired" or the joint is a source of "uncontrollable pain". These conditions can occur in gonarthrosis, rheumatoid arthritis, post-traumatic arthrosis, systemic disorders of the locomotor system and post-traumatic conditions (eg intra-articular fractures).

The doctor recommends an endoprosthesis after exhausting conservative therapy, which includes drug therapy, rehabilitation, lifestyle modification, physical therapy and balneotherapy.

Contraindications
The main contraindication to alloplasty, apart from general internal contraindications' (advanced atherosclerosis of CNS arteries, ischemic disease of the lower extremities, severe cardiopulmonary disease), is the presence of any infection in the organism. The infection leads to the loosening of the implant from the bone and thus its failure. If the total endoprosthesis becomes infected, a ``two-stage reimplantation'' using a cemented spacer is used. The spacer serves mainly to release antibiotics, also to prevent excessive contraction of soft tissues and allows partial weight bearing.

Complications
Various complications can arise after the operation, we divide them into general   and . Local complications include fractures, infections, knee instability, patellar instability, popliteal vessel injury, and tendon rupture m. quadriceps femoris and lig. patellae. General complications can include phlebothrombosis, thromboembolic disease and stroke.

Rehabilitation
The rehabilitation of patients after a total knee joint endoprosthesis tries to restore the broken functions of the joint as quickly and perfectly as possible, to minimize the health consequences and thus return the patient to an active life as much as possible.

Preoperative rehabilitation
Before the operation, the patient is prepared both physically and psychologically. The patient is informed about possible complications that may occur after the operation. He is also introduced to exercises for the operated lower limb, as well as exercises for the upper limbs, which he will need to strengthen in order to walk on crutches. This is followed by training in proper walking on crutches without putting weight on the operated limb. For organizational reasons, pre-operative rehabilitation does not always take place.

Postoperative rehabilitation during hospitalization
Total endoprosthesis is among operations with a high risk of thromboembolic disease. Therefore, mobilization and positioning of the limb into flexion and extension begins immediately after the operation. Breathing gymnastics and fitness exercises for non-operated limbs are also performed.

Targeted physiotherapy is focused at increasing the range of motion in the knee joint. Active exercise of flexion and extension is alternated with the use of a motor splint. The goal of rehabilitation is to achieve maximum extension and at least 90° flexion. Emphasis is also placed on isometric strengthening of the quadriceps femoris muscle, especially the vastus medialis muscle, which tends to be weakened after surgery. The cause is probably a greater load on the muscle due to postural tonic posture.

The patient is usually verticalized on the second day after surgery. Step by step, standing and walking with support aids (mostly French canes) are rehearsed. Great emphasis is placed on the correct movement stereotype. After mastering walking on flat terrain, approximately 5-10 the day after the operation, he begins to practice walking up stairs and on uneven terrain. The patient continues to learn independence and self-sufficiency with crutches.

After about two weeks, the stitches are removed. The patient should be capable of maximal extension, at least 90° flexion and independent walking. The patient can turn on his stomach and is usually discharged home.

Rehabilitation program after hospitalization
The goal of the post-hospitalization rehabilitation program is to achieve optimal functional status and prevent later complications. It mainly focuses on strengthening the weakened musculoskeletal system and correct posture. The optimal state usually occurs three to six months after surgery'.

It is important to choose and recommend appropriate physical activities to patients, such as light hiking with the use of sticks, light cycling, swimming except breaststroke. Patients should avoid hopping, squatting, kneeling and standing for long periods of time.

Patients come regularly for clinical and X-ray examinations, the main X-ray examination is scheduled three months after the operation.

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