Pre-patellar Bursitis


What is a bursa?

In places around the body where there is a prominent area of bone underlying the skin, there is often a thin sack of fluid sitting in between the bone and the skin that helps prevent the skin from rubbing on the bone. This kind of sac of fluid is called a bursa. The multiple for ‘bursa’ is ‘bursae’. Places where bursae are found include:-

  • The tip of the elbow = the olecranon bursa
  • Under the outer edge of the shoulder = the subacromial bursa
  • Overlying the outer side of the hip = the trochanteric bursa
  • Under the skin at the front of the knee = the pre-patellar bursa or infra-patellar  bursa

The pre-patellar bursa sits directly in front of the patella (kneecap). The intra-patellar bursa is just below this, just lower down than the patella, sitting in front of the patellar tendon and the top part of the tibial tuberosity.


What is bursitis?

Any bursa can become inflamed. Occasionally this happens after some kind of trauma, but most often it just occurs fairly spontaneously. When a bursa is inflamed, this is called ‘bursitis’.

Bursitis causes a burning pain, swelling and warmth/heat specifically in the area of the bursa. Sometimes this is intermittent, and the swelling comes and goes. Sometimes the bursitis can be quite severe, with marked swelling and pain. On some occasions a bursa may be very swollen but not particularly painful.

If a bursa is inflamed due to an actual infection, then this can be severely painful and the patient can be quite generally unwell, in which case fairly urgent treatment will be required.


Investigation

The best investigation to look at a bursa and to diagnose possible bursitis is an ultrasound scan. At the same time as doing the scan, the radiologist (X-ray doctor) might also aspirate the bursa (put a needle into it to take a sample).  Aspirating a severely swollen inflamed bursa can give rapid pain relief, and sometimes it might be appropriate to also inject some local anaesthetic for further pain relief and possibly also some steroid/cortisone too, which is a very powerful anti-inflammatory (although this should never be injected if there is a suspicion of any infection being present).


Treatment

Treatment depends on the severity of the bursitis, and can include:-

- rest, ice, anti-inflammatories

- aspiration of fluid (ideally under ultrasound-guidance)

- injection of local anaesthetic and steroid/cortison

- antibiotics (if there is infection present)

- surgical excision of the bursa

Surgical excision of a persistently troublesome bursa is rarely actually ever needed. It has a very high success rate for being curative, but it is always reserved for those bursae that fail other forms of treatment and that keep recurring and which are actually causing the patient enough trouble for surgery to be justified.