Tendonitis literally means inflammation within a tendon. Tendons connect muscle to bone (ligaments connect bone to bone), they have less blood flow than muscles, resulting in a longer healing period than their muscle neighbours, they are less elastic but very strong and flexible. Tendonitis can occur anywhere a tendon joins muscle to bone, but is more often associated with the upper and lower limbs e.g. Achilles tendonitis (at the back of the heel), patellar tendonitis (below the knee).
The inflammation is typically a result of over exertion in sports or other physical activities. When the tendons become too loaded or placed under too much strain they become tender and sore, there is reduced and limited range of movement and the area may swell.
Tendonitis may also be a result of repetitive strain injuries (RSI), where repetitive, smaller movements for prolonged periods of time will cause the same result e.g. typing, line work in factories, sewing etc.