Radiosynoviorthesis

Radiosynoviorthesis (RSO, from radioactive isotope, synovial joint lining, orthotic reconstruction; RSO for short) is one of the nuclear medicine procedures used therapeutically in rheumatology and orthopedics for the treatment of chronic inflammatory joint diseases. The application of radiosynoviorthesis provides the possibility of reconstruction of the synovium (inner lining of the joint cavity without cell contacts). The reconstruction of the synovium is based on the use of beta-emitters (radionucleotides). Beta radiation is an ionizing radiation that occurs during a radioactive decay, beta decay. These radionuclides are applied into the joint cavity so that an existing inflammatory process can be inhibited (stopped). The use of the procedure thus represents an alternative to surgical removal of the synovium.

Indications (areas of application)

  • Rheumatoid arthritis – this clinical picture represents the main indication for the use of radiosynoviorthesis. Depending on the stage of arthritis, nearly 75% of early rheumatoid arthritis can be successfully treated with radiosynoviorthesis. If the treatment takes place at a later stage, the chances of success are significantly reduced.
  • Osteoarthritis – also in the case of osteoarthritis, radiosynoviorthesis is a useful procedure in the treatment. Compared to rheumatoid arthritis, however, the chances of success of the therapy are lower.
  • Hemophilic arthropathy – this clinical picture is an arthrosis, which can be caused by persistent bleeding. It usually affects patients who suffer from a blood clotting disorder, usually hereditary. The disorder induces bloody joint effusions that lead to scarring of the joint interior. Through radiosynoviorthesis, this hemarthrosis can be successfully treated in about 90% of cases.
  • Pigmented villonodular synovitis – in this rare disease of the joint mucosa, which is accompanied by joint effusions and swelling, radiosynoviorthesis can be used as an alternative to removal of the mucosa or radiotherapy.
  • Arthritis psoriatica – in arthritis triggered by psoriasis (psoriasis), radiosynoviorthesis is a recognized and useful therapeutic option.

Contraindications

  • Repeat therapy within a few days – repeat radiosynoviorthesis should not be performed within three months.
  • Infectious arthritis (joint infection) – the use of radiosynoviorthesis in a diagnosed joint infection is an absolute contraindication.
  • Gravidity (pregnancy) – radiosynoviorthesis must not normally be used during pregnancy to avoid endangering the child.
  • Lactation phase (breastfeeding)
  • Growth age – the procedure should not be used in children in any case, because the therapy may cause later impaired mobility.

Before treatment

  • Confirmation of diagnosis-before using the therapeutic procedure, the indication for the procedure must be considered confirmed. The use of radiosynoviorthesis is usually not a primary therapeutic option, but is used when systemic therapeutic attempts fail.
  • Inflammatory activity – before performing radiosynoviorthesis, inflammatory markers should be detected in the blood. A particular focus here is on the inflammatory markers CRP (C-reactive protein), erythrocyte sedimentation rate (ESR) and the various globulins.

The procedure

Radionuclides (yttrium90 for the knees; rhenium186 for the shoulder, elbow, wrist and ankle; erbium169 for the finger, metatarsal and toe joints) are injected into the respective joint. The coupling of the radionuclides to colloids (particles in liquid) causes the radioactive substance to remain in the joint longer. Currently, only β-emitters (beta-emitters) and not γ-emitters (gamma-emitters) are used in radiosynoviorthesis to prevent harmful radiation exposure to the patient. The selection of the radioactive substance depends, among other things, on the joint to be treated. For therapeutic use on the knee joint, Yttrium90 is primarily used, while Rhenium186 is used on the shoulder joint, among others.The beta rays significantly reduce local hyperemia (increased blood supply) and induce inactivation of the existing inflammatory cells. Furthermore, the destructive (devastating) effect of the beta rays causes a connective tissue transformation of the synovium (synovial membrane). This can last up to 3 months. To avoid additional infection, the injection of the radioactive substance is performed under strictly aseptic conditions and X-ray fluoroscopy. A steroid (inflammation inhibitor) may also be applied in parallel with the radioactive substance.

After the treatment

  • Immobilization of the joint – after the radioactive substance has been applied, the joint must be immobilized for approximately 72 hours to ensure that premature removal of the radionuclide is prevented. The effect of the applied substance is thus prolonged.
  • Other therapeutic measures – in addition to the administration of the radioactive substance, radiosynoviorthesis can be extended by additional measures such as the application of antiphlogistic (anti-inflammatory) drugs.

Possible complications

  • Fever
  • Cephalgia (headache)
  • Fatigue
  • Joint effusions (synonyms: hydarthros, hydrops articularis).