Joint puncture is a nonsurgical diagnostic procedure in rheumatology and orthopedics that can be used to examine unclear effusions in the joint area or to evaluate an infection of a joint.In most cases, the swelling of the tissue in the joint area is due to an inflammatory process. In a joint puncture, a needle is inserted into the affected joint to obtain information about the process of formation of the effusion. In addition to the necessary joint puncture, the diagnostic clarification of a suspected joint infection also includes the performance of a laboratory examination in which the leukocyte count (number of white blood cells) is determined and a differential blood count is obtained. Furthermore, the C-reactive protein, an important inflammation parameter, must be determined. An increase in the concentration of C-reactive protein would indicate, among other things, acute inflammation. In addition to the laboratory diagnostic procedures described above, native radiographs of the affected joint are also taken. Additional diagnostic procedures, such as magnetic resonance imaging (MRI), computed tomography (CT), or scintigraphy, are necessary for special questions in order to rule out possible causes of infection, among other things.
Indications (areas of application)
- Analysis of an unclear joint swelling – the most important field of application represents the clarification of an existing swelling or an existing effusion.
- Pain relief – if there is an inflammatory process with an effusion, the joint puncture can be used to remove the effusion fluid from the joint and thus reduce the pain. In addition, removal of the fluid can also prevent overstretching of the surrounding tissue structures.
Contraindications
Except for specific contraindications such as a massive change in blood clotting, there are no known contraindications.
Before surgery
- Since this is a nonsurgical procedure, there are almost no preparatory measures to be performed on the patient side before the puncture is performed. To contain the inflammatory process as much as possible before the puncture, active cooling of the effusion area should be performed.Caution. The application of heat is in no way suitable as a therapeutic measure.
- If the patient has already received an antibiotic before the puncture, it is of great importance that this is communicated to the attending physician.
The surgical procedure
The aim of the puncture of the affected joint is to aspirate the synovium (synonyms: synovial fluid, synovial fluid, “synovial fluid”) or the effusion fluid, respectively, to be able to examine it microscopically and bacteriologically (microscopic and bakeriological synovial analysis). Furthermore, a microscopic cell differentiation of the synovia as well as chemical or immunological examinations are performed. If necessary, it is also possible to apply pharmacologically active substances directly into the joint during a joint puncture.The extraction of the synovia, which occurs in small quantities, is important for diagnostics, as it also has a filtering function in addition to cartilage nutrition and the reduction of frictional resistance. Because of this, substances with a small size such as proteins (total protein), uric acid and lactate dehydrogenase (LDH) can be easily detected in the synovia. On the basis of these substances, initial statements on the pathogenesis (development of the disease) are possible. Often, a macroscopic (with the naked eye) turbidity of the synovial fluid can already be detected in the case of inflammation. The turbidity directly indicates an inflammation-related increase in the cell count. In addition, the presence of blood components may indicate a traumatic (accident-related) process.Other immunological tests, such as C3 complement, C4 complement, rheumatoid factor, C-reactive protein (CRP), antistreptolysin O (ASL), and antinuclear antibodies (ANA), are of particular importance in the diagnosis of rheumatologic diseases. Based on joint puncture and other diagnostic procedures, it is possible to classify joint infections into individual stages:
- Stage 1 – this stage is characterized by the presence of a cloudy synovial fluid. In addition, redness of the synovial membrane is evident, which facilitates staging. However, it is of important significance that no radiological changes may be present in stage 1.
- Stage 2 – to distinguish this stage from stage 1 serves the presence of fibrin deposits (special protein involved in inflammatory processes). Under the microscope, macrophages (phagocytes) can be seen breaking down the fibrin that has formed. Furthermore, there are no radiological changes even in stage 2.
- Stage 3 – in this stage can now be seen relatively clearly in addition to the redness also a thickening of the synovial membrane. Again, no radiological changes are present.
- Stage 4 – in the fourth stage, radiologically recognizable osteolysis (dissolution of bone substance) occurs and cyst formation becomes apparent. In addition, aggressive pannus formation is present. The pannus is covering tissue around the joint surface, which is rich in vessels and enzymatically dissolves the bone.
After surgery
After surgery, exercise and weight-bearing should be avoided for the time being. It is also important that the medications recommended by the doctor are taken in exact doses to prevent reinfection (re-infection) of the joint.
Possible complications
- Nerve and vascular lesions – penetration of the cannula into the joint, for example, is associated with the risk of destruction of vessels and nerves. Mechanical damage to the joint may also occur as a result of cannula insertion into the joint.
- Joint infections – although joint puncture is an important method for investigating inflammatory joint disease, skin germs and other bacteria can be applied to the joint through the cannula, so a secondary infection may result from the puncture.
