Joint and Soft Tissue Aspirations
An aspiration draws fluid out of a swollen joint or soft tissue swelling using a fine needle. It relieves pressure and pain, and the fluid itself can be sent for analysis to help establish why the swelling happened. The procedure is also known as arthrocentesis, and it is one of the most common procedures used for muscle and joint problems.
It is most often carried out at the knee or shoulder. A soft tissue swelling such as a haematoma, a bursa or a ganglion may also be suitable.
At Meyer Physio every aspiration is performed under live ultrasound guidance, so the needle is watched onto the target throughout.
When is an aspiration needed?
There are two reasons, and often both apply at once.
Where a joint is swollen without a clear explanation, a sample of the joint fluid can help identify the cause. It can be tested for bacteria, for crystals, or for abnormally high levels of white blood cells, which helps distinguish infection and inflammatory arthritis from mechanical causes.
Where the swelling itself is the problem, removing the excess fluid reduces pressure inside the joint and eases pain directly. A tense effusion can be the reason a knee will not bend, and draining it can restore movement in the same appointment.
How is an aspiration performed?
The skin around the site is carefully disinfected first, to stop bacteria entering the joint. Sterile disposable gloves are worn, and cannulas and syringes are unpacked immediately before use.
The fluid is drawn out through the syringe. Where clinically appropriate, medication such as a steroid injection can be given through the same needle in the same procedure, which avoids a second appointment and a second needle.
Do you use diagnostic ultrasound?
Yes, for every aspiration. Diagnostic ultrasound locates the fluid before the procedure begins and monitors the needle throughout.
This matters more than it may sound. Fluid is not always where it is expected to be, particularly in a shoulder or a hip, and a small collection can be missed entirely by feel. Ultrasound also shows whether the swelling is fluid at all, since a thickened joint lining can feel much the same from the outside and will not drain.
How do I prepare?
No special preparation is usually needed.
Please tell us in advance if you take anticoagulant or antiplatelet medication, or if you have diabetes, so that your individual risk can be assessed.
What happens immediately afterwards?
A pressure bandage is often applied. The joint usually needs to be kept still, and for how long depends on the cause of the swelling and whether medication was injected at the same time. You will be told what to do before you leave.
Where fluid has been sent for analysis, the results guide what happens next. An aspiration relieves the symptom, and the reason for the swelling still needs addressing, whether that is osteoarthritis, an injury, or an inflammatory condition needing onward referral.
Is an aspiration painful?
Joint aspiration typically feels much like having blood taken.
What are the risks?
There may be bleeding into the joint or soft tissue, and inflammation at the needle insertion site is possible. If medication is injected, it may cause a feeling of pressure or a brief burning sensation, and can have side effects such as allergic reactions. Anti-inflammatory medication can cause facial redness, raised blood pressure, a racing heartbeat and flushing.
The most significant risk is infection from bacteria entering the joint. That risk varies with what is done during the procedure and which joint is involved. Diabetes or a weakened immune system increase it.
What does an aspiration cost?
Every appointment lasts a full hour. Current prices are listed on the prices page. No GP referral is needed to book.
Joint aspiration in Weybridge
Meyer Physio is an advanced practice physiotherapy and musculoskeletal diagnostic clinic on Baker Street in Weybridge. Scanning, aspiration and injection all take place in the same appointment, with no waiting list.