M67.35: Transient synovitis Pelvic region and thigh

The thin membrane of a joint capsule or a tendon sheath in your pelvis or thigh has become inflamed.

The pelvis is made up of different bones. There are 3 bones on each side which each merge to form one large pelvic bone. A joint connects these two large pelvic bones to the sacrum at the back of the body. The sacrum is part of the lower spine. The two pelvic bones plus the sacrum form a bony pelvic ring or girdle. In front, the two pelvic bones are tightly joined to one another by ligaments and cartilage fiber. The hip joints are outside, to the side of the pelvis. They connect the pelvis to the thighbones. The hip joints enable the legs to be moved in different directions.

Joints are encased in a joint capsule. A tendon sheath is a covering for the tendon. It cushions the tendon and contains a small amount of fluid. This reduces friction between the tendon and its surroundings. Joint capsules and tendon sheaths have a thin membrane lining inside.

Inflammations of the thin membrane of joint capsules or tendon sheaths can be caused by pathogens or toxic substances.

When the thin membrane of a joint capsule or tendon sheath becomes inflamed, it can be painful. It may also be that you are no longer able to move the affected area of your body properly.