Subcortical cyst is a condition that forms inside shoulders, knees and hips. Normally, the sacs are filled with hyaluronic acid, a liquid that lubricates the joint. For the patients with subcortical cyst, the sacs are filled with fluid.
Subcortical cyst is a sign of osteoarthritis. But there are some situations that patients have osteoarthritis without having subcortical cysts.
Subcortical cyst doesn't have distinctive symptoms and the symptoms are similar with those of osteoarthritis.
The symptoms include:
- A small, fluid-filled sac protruding from the joint
- Discomfort and mild to moderate pain
- Limited joint flexibility
An X-ray is a must for diagnosis. If a cyst isn't obvious on an X-ray image, an MRI of the affected joint will be used.