pathology: condition after total endoprosthesis

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condition after total endoprosthesis

Definition of

Total endoprostheses (TEP) are the last treatment option when it is no longer acceptable for a joint to remain in the body, for example due to excessive destruction, severely restricted functionality or chronic pain that cannot be suppressed or can only be suppressed with unacceptable long-term pain medication. For a long time, they were primarily used to treat older patients, but nowadays they are also being prescribed to younger and younger people because their quality of life and self-expression have suffered too much as a result of advanced joint wear and tear, often due to chronic pain. This is often due to the cumulative effect on the musculoskeletal system of unphysiological stress in sport. One reason for this is that new sports are constantly being invented, many of which are not physiological for the musculoskeletal system.

This refers not only, but also to unforeseen events in the course of sports practice with or without contact with opponents, such as falls, but also to the cumulation of wear-promoting effects. After exhausting conservative measures such as physiotherapy and exercise therapy and many other supportive measures such as physical therapy, intra-articular injections and pain and inflammation-relieving medication, the final step is an artificial joint. The durability of such a joint replacement depends on the affected joint, the condition of the artificial joint and the use of the joint. As a rule, you cannot expect more than 15 to 20 years. In some cases, partial weight-bearing must be ordered post-op or certain movements and loads must be excluded for some time or permanently. Of course, this also applies to sports. The developers of the endoprostheses subject them to tests for suitability for everyday use, but not for suitability for all possible sports.

To make a rough distinction, sports are divided into low impact and high impact sports: low impact sports are those with limited stress on the joints and muscles due to easily controllable, predictable movements and the absence of potentially harmful contact with opponents. The absence of constant impact-like stress is also one of the criteria. Therefore, sports such as cycling, swimming, walking, cross-country skiing, moderate strength training and rowing can be found here. The high-impact category includes most team sports with potential contact with opponents as well as sports with abrupt jumps, turns, landings and repeated impact on the joints. This includes some of the most common sports such as soccer, handball, basketball, volleyball, athletics and running. Abrupt start and stop movements in particular, as well as the opponent contact that leads to them, are known to cause the endoprostheses to loosen.

Basic risk factors that are not sport-specific include the possibility of injuries and falls, such high or prolonged loads that the implant can become loose, and the possible abrasion of particles from the articulating surfaces.

On the other hand, there are the following possible positive factors, again not specific to any sport: the load leads to an improvement in bone density and therefore better ingrowth of the prosthesis into the bone, the muscles and also the bones are generally strengthened, which reduces the specific risk for the replaced joint, and the risk of falling is lower in a body trained in strength, coordination and proprioception. In addition, endurance sports in particular help to prevent obesity, which poses an additional risk of both loosening and wear of the artificial joint. An adapted sports program also protects against other phenomena, such as those caused by narrowness. In addition, sport has positive effects on the psyche, including psychoimmunology. Last but not least, sport improves confidence in the artificial joint and its functioning and integration into the body, as well as possibly altering proprioception.

There are several factors that can lead to the need for premature replacement:

  1. Loosening due to strain
  2. Abrasion of the joint surfaces
  3. Errors detected ex post during installation
  4. Osteolysis
  5. Infection of the bone
  6. Fractures affecting the bones holding the TEP
  7. Dislocations that damage the TEP or the supporting bone
  8. traumatic damage

Some of the above factors are noticeable to the patient through a feeling of joint instability. If this is accompanied by local signs of inflammation or a fever, this is a sign of inflammation and an acute need for action. Germs that lead to inflammation may have entered the open wound during the operation or reached the bone surrounding the TEP via the bloodstream, for example if there are infections of the nasopharynx, teeth or jaw. Infections that arise in causal connection with the operation itself can occur with a delay of up to three years. Early infections within the first few weeks are always attempted to be treated in a TEP-preserving manner by taking specific action against the pathogen once it has been detected. Diabetics, obese patients and immunosuppressed patients are naturally predisposed to TEP infections. In addition, ligament insufficiencies may necessitate a repeat operation. A reoperation to replace the prosthesis is generally more complicated than the initial operation. Only the parts that are necessary should be replaced. Replacement of parts that are firmly fused to the bone should be avoided, as in these cases the bone substructure would be further reduced, resulting in less stability. However, if this is necessary, a two-stage replacement is often used, in which a spacer is implanted first, which continuously releases antibiotics to combat the inflammation, so that the new TEP is only inserted when no more pathogens are detectable. After a TEP has been removed, large bone defects can occur, which must be treated with methods such as a bone graft before a new TEP can be implanted.

Complications

  1. Loosening of the implant
  2. Abrasion from the articulating surfaces, which remains in the joint as free particles or from which chemical components also pass through the joint capsule.
  3. Renewed need for joint replacement in the event of non-compliance with key parameters or even despite compliance after approx. 15 – 20 years.
  4. leg length difference in hip TEP by sintering the implant further into the medullary cavity in the case of pre-existing osteoporosis