Radiosynoviorthesis (RSO)
Radiosynoviorthesis is a method of treating joint inflammation, such as chronic polyarthritis or activated arthrosis. A radioactively labeled medication is injected directly into the affected joint, which emits ionizing radiation known as beta radiation. Since this radiation has a small range of a few millimeters in the tissue, the radiation is limited to the joint mucosa, which is thereby obliterated. This leads to a decrease in the inflammatory processes of the synovial membrane.
Preparation for RSO:
- Detailed medical history about the disease and previous treatments
- Informed consent from the patient
- Clinical examination of the affected joint (e.g. swelling, redness)
- Bone scintigraphy in triple phase technique
- X-rays of the affected joint
- Ultrasound of the joint to document a possible effusion/ cyst (knee joint)
- Rarely: Magnetic resonance imaging of the affected joint
Which joint diseases are treated by the RSO?
RSO is used to treat chronic inflammations of the synovium (synovialitis). The presence of such a disease is clarified during preparation.
The contraindications for RSO
- Pregnancy
- Breastfeeding
- Local infections and skin diseases in the vicinity of the injection site
- Knee joint cyst (Baker cyst)
- Massive hematoma in the joint
How is the RSO carried out?
Initially, a thin needle is introduced into the affected joint under sterile conditions and a contrast medium is injected and X-ray fluoroscopy is used to ensure that the needle is located in the joint.
The radioactive substance is injected into the joint through the same needle.
After application of the radioactive drug, an additional cortisone solution is injected to acutely improve the inflammatory symptoms.
After the treatment, the distribution of the radioactive drug in the joint is confirmed under the gamma camera and the distribution of radioactivity in the joint is controlled (joint scintigraphy).
The treated joint should be immobilized for at least 48 hours using a splint or bandage. This procedure requires thrombosis prophylaxis for 48 hours. The joint should then be relieved and spared for another one to two weeks. Stationary admission for treatment is usually not necessary.
Overview of the radionuclides used and their properties:
Substance | Half-Life of Radiation | Max. Range in tissue | Treated |
Yttrium-90 | 64 hrs | 11 mm | knee joint |
Rhenium-186 | 89 hrs | 3.6 mm | hip-, jump-, shoulder-, elbow-, hand- joint |
Erbium-169 | 226 hrs | 0.3 mm | ankle or wrist joints |
What side effects of RSO are known?
Serious side effects after RSO are extremely rare.
Rarely, a painful, inflammatory reaction can occur in the treated joints. If the radioactive medication gets into the tissue outside the joint cavity, this may lead to skin or muscle necrosis. For this reason, immobilization of the treated joint is absolutely necessary for at least 48 hours.
In individual cases, a febrile reaction has been observed after the injection of the radioactive drug. Allergic reactions to local anesthesia or the X-ray contrast medium are possible.
How often is RSO performed?
Usually this therapy is carried out once. If symptoms recur after an initial reduction of the inflammatory symptoms, the treatment can be repeated.
Is follow-up after RSO necessary?
About 4-6 months after the RSO, an outpatient bone scintigraphy is performed to assess the success of the therapy.
