A bursa is a small fluid-filled sac that acts as a cushion between the bone and muscles, tendons and skin. They allow your joints to move freely and ease rubbing.
Occasionally this sac can become inflamed or irritated and this is called ‘Bursitis’. This is commonly seen in the major joints of your body: shoulders, elbows, hips, knees or the ankle. It is often mistaken as arthritis due to the location of the pain experienced.
There are a few locations of bursa in the knee. The most commonly implicated is the ‘prepatellar bursa’ (aka housemaids or carpenters knee), this is in front of the knee cap and reduces friction in flexion and extension of the knee but due to its location it is prone to trauma from kneeling and blunt force impact.
Just above the kneecap, is the ‘suprapatellar bursa’, this bursa allows the quadriceps to glide over the lower part of the thigh bone when flexing and extending and is generally implicated in the same way as the prepatellar bursa.
As well as this, there is the ‘infrapatellar bursa’ below the kneecap. This can develop due to kneeling, chronic overuse and irritation and is commonly associated with ‘jumper’s knee’ and patellar tendonitis. Lastly is the ‘pes anserine bursa’; with this patients report medial knee pain around the knee joint line.