Prepatellar bursitis aspiration and steroid injection

What is prepatellar bursitis?

This condition refers to swelling and inflammation of a sac (called the prepatellar bursa) at the front of the knee cap, just underneath the skin. It is sometimes referred to as Housemaid’s knee, as it can be associated with kneeling activities.

What are the causes of prepatellar bursitis?

Local trauma, like a direct fall and hitting the knee
Manual workers with activities that involve repetitive or prolonged kneeling like carpenters and builders.
Inflammatory conditions like Gout.
Rarely prepatellar bursitis can be due to infection, or the bursa can become infected if there is a break in the skin overlying the bursa. This is a serious condition associated with local pain, redness and swelling and sometimes raised temperature. Please see your doctor if you have such symptoms as you may need antibiotics treatment.

How is prepatellar bursitis diagnosed?

Usually, the condition is suspected clinically and confirmed by imaging. Ultrasound and MRI are suitable modalities for the assessment. Ultrasound is excellent for establishing the diagnosis and assess the size of the bursa and the presence of any inflammatory changes. Furthermore, it is very useful to perform ultrasound-guided aspiration and steroid injection.

What other conditions that can mimic pre patellar bursitis?

Other causes for swelling and pain at the front of the knee include:

To find out more about other causes for pain/swelling at the front of the knee, please see our article.

What is the treatment for prepatellar bursitis?

Prepatellar bursitis can improve gradually with conservative management, including avoiding irritating the area, wearing protective knee padding, using anti-inflammatory tablets, and treating the underlying cause (if possible). If the prepatellar bursa is large in size or significantly inflamed, causing severe pain and not responding to conservative management, then an ultrasound-guided aspiration and steroid injection are suggested.

Can pre patellar bursa be aspirated?

Yes. Aspiration of the bursal fluid means inserting a small needle into the bursa and extracting the fluid. This is usually combined with a steroid injection. Corticosteroid (cortisone) is a well-established anti-inflammatory medicine used to manage various inflammatory conditions. Steroid injections reduce the inflammation in the targeted area and are usually useful in managing pre-patellar bursitis.

We always recommend doing aspiration and injections under ultrasound guidance. There is significant evidence that injections are less painful and more accurate when done under ultrasound guidance. Ultrasound guidance allows for accurate needle placement into the site of fluid within the bursa and, thus, more successful aspiration and delivery of the corticosteroid medicine to the exact site of inflammation. Injecting under ultrasound guidance allows for visualisation of the adjacent structures so they can be assessed before performing any injection and reduces the risk of tissue injury at the injection site.

How is pre patellar bursitis aspiration and steroid injection done?

The area is assessed with ultrasound first to determine the best approach. The area will be cleaned and prepared. Then, after numbing the tissue under the skin using a small dose of local anaesthetic, a small needle is inserted into the bursa under ultrasound guidance and the fluid is aspirated. After the injection, usually pressure is applied to the area to prevent the fluid from building up again. A compression band is also recommended to apply pressure over the area and reduce the possibility of fluid recurrence.

What are the possible side effects of pre-patellar bursitis aspiration and steroid injection?

The procedure is usually very safe, particularly when done under ultrasound guidance. There is a possibility of recurrence of the fluid and a small possibility of infection. To read out more about steroid injections and possible side effects, please see our FAQs.

Summary

Prepatellar bursitis (Housemaid’s knee) is a common condition that results from repeated pressure or irritation to the front of the knee cap, resulting in the fluid build-up, swelling and pain. It is benign (non-worrying) but can be resistant to simple treatments. Ultrasound-guided aspiration and steroid injection can be helpful in the management.