What is a bursa?
Bursae (plural) are thin, closed, fluid-filled sacs that provide a gliding surface to reduce friction between bone and the surrounding soft tissue structures hence, they are commonly found around joints. They are lined with synovial membrane and normally filled with a sliver of fluid.
Bursitis is inflammation of a bursa characterised by thickening of the synovial lining and accumulation of excess fluid.
What is prepatellar bursitis?
Prepatellar bursitis is inflammation of the prepatellar bursa, the thin fluid-filled sac positioned in front of the kneecap (patella).
Causes of prepatellar bursitis
- Pressure from frequent kneeling is a common cause so occupations that require this position (plumbers, roofers, carpet layers, and gardeners) are at greater risk of developing the condition. The alternative name of housemaid's knee reflects the predominant group that developed the condition when it was first described.
- An acute trauma from a blow to the front of the knee or a fall.
- Overuse - Repetitive bending of the knee with activities like cycling or squatting can trigger the condition.
- Recurrence - If you have had bursitis before it can reoccur sometimes without a clear trigger.
- Infection - When kneeling it is possible for a small sharp object to break the skin and introduce infection causing a septic bursitis.
- People with a low grade systemic inflammatory condition like gout, rheumatoid arthritis or tuberculosis, or patients with diabetes mellitus, are more susceptible to developing prepatellar bursitis.
What are the symptoms of prepatellar bursitis?
Symptoms of acute bursitis include tenderness at the site of the bursa, redness, warmth, swelling, and loss of range of motion. Worsening pain, spreading redness, feeling fatigued and generally unwell should raise suspicion of a septic bursitis.
Chronic bursitis can be a painless swelling of the bursa. Even after the swelling settles you may feel nodules or crepitus over the front of the knee.
If you think you might have septic bursitis you should arrange to see your physician urgently.
How do you diagnose prepatellar bursitis?
Making a diagnosis from the medical history and physical examination is fairly straight forward. An in-clinic ultrasound scan can be used to confirm the fluid is in the bursa in front of the knee and not in the knee joint itself.
X-rays may be ordered if there is suspicion of a fracture or a foreign body in the soft tissue. In addition, blood tests may be performed to rule out infection or a medical condition.
If there is concern over the possibility of infection aspiration (drainage) of the bursal fluid may can be carried out and the content sent to the laboratory for analysis.
Prepatellar bursitis affects all age groups, but is more likely to be septic when it occurs in children.
How do you treat prepatellar bursitis?
Treatment depends on how severe the problem is, whether it is an acute or chronic case and whether it is an aseptic (not infected) or septic (infected) bursitis.
Acute cases will respond well to rest and nonsteroidal anti-inflammatory drugs. Fluid removal (aspiration) and corticosteroid injection, administered under ultrasound guidance, is routinely used for cases that do not settle with the initial conservative measures.
Chronic cases may need surgery to remove any loose bodies or fragments within the bursa.
Infected cases need urgent medical attention for antibiotic treatment and rarely drainage.
The treatment plan also includes advice about avoiding further aggravating factors like excessive weight bearing, repetitive movements, and poor posture.
