A unicameral (simple) bone cyst is a cavity found within a bone that is filled with straw-colored fluid. It is a benign (non-cancerous) condition.

Unicameral bone cysts (UBC) are usually found in patients under 20 years of age. Unicameral bone cysts occur in one bone, in one location. The location of the cysts tends to be in the upper arm (proximal humerus) or thigh bone (proximal femur). Less common locations include the pelvis, ankle (talus) or heel (calcaneus).

Surgical removal of a bone cyst may be needed if it becomes painful, or an area of the bone starts to thin out. Thinning of the bone may eventually cause fracture (breakage).

Nonsurgical Treatment
A unicameral bone cyst without pain or other symptoms is just monitored using X-rays and doctor examinations.

Surgical Treatment
Surgery may be needed if the cyst is in a location that might cause the bone to break. Only unicameral bone cysts at risk of a pathologic fracture need treatment.

A unicameral bone cyst in a structurally compromising location may need surgery including scraping the inside of the bone (curettage). The hole left following this may require donor bone or a bone graft substitute to fill the defect, such as CERAMENT®, which can be injected in a percutaneous or minimally invasive technique through a needle into the cyst.

Depending on the size and location of the cyst, treatment with an internal fixation device may also be needed.