The synovium, which is also sometimes called the stratum synoviale or synovial stratum, is connective tissue that lines the inside of the joint capsule. A joint capsule, also called an articular capsule, is a bubble-like structure that surrounds joints such as the shoulder, elbow, wrist, hand, knee, foot and ankle. It is composed of a tough, outer layer called the fibrous stratum and a soft inside layer (the synovium). Contained inside both layers is synovial fluid, a viscous liquid that lubricates the joint to reduce friction on the articular cartilage during motion.
Synovitis causes
The most common cause of synovitis in an involved, stable person is overuse of the joint, for example in athletes or individuals whose occupations require repetitive stress movement, such as lifting or squatting.
However, in individuals that have some form of inflammatory arthritis, synovitis is also normal. Excessive synovium development is part of an irregular immune response in these patients, where the body misidentifies its own natural cartilage as a foreign material that has to be targeted.
Eventually, cartilage loss affects the surface of the joint and contributes to the weakness and discomfort characteristic of all forms of arthritis. (This type of inflammatory response is not involved in osteoarthritis, the more common form of arthritis.)

Treat synovitis with essential oils
Massage the inflamed joint with a small amount of the following oil:
Basic blend – massage
Chamomile roman | 10 drops |
Eucalyptus radiata | 5 drops |
Rosemary | 2 drops |
Lavender | 3 drops |
Peppermint | 2 drops |
Blend together and then dilute by adding 3–5 drops to each teaspoon (5 mL) of carrier oil.
Other Essential Oils That Could Be Used to Treat This Condition: tea tree, *juniper berry (Juniperus communis), *cajuput (Melaleuca cajuputi), *plai (Zingiber cassumunar), *ginger (Zingiber officinale), *immortelle (Helichrysum italicum)