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Unicameral Bone Cyst

A unicameral (simple) bone cyst is a cavity found within a bone that is filled with straw colored fluid. It is a benign condition (non-cancerous) usually found in patients younger than 20 years of age. UBCs occur in one bone, in one location.

How are UBC’s diagnosed?

Plain X-Rays – Show a hollow cavity in the bone with a well-defined cortical rim.

Computed Tomography (CT) Scan – Ordered when the UBC is not typical in its appearance to help determine the architecture of the bone. 

Common Presenting Symptoms

  • Asymptomatic
  • Pain with weight-bearing activities from thinning of the bone
  • Pain with a pathologic fracture through the cyst, the affected arm or leg may have pain, swelling and deformity 

Treatment Options

Non-Surgical – A UBC without pain or other symptoms that the doctor discovers when evaluating another problem can be watched with repeated X-rays and routine doctor exams. Pathologic fractures occasionally incite a healing process not requiring surgical intervention.

Surgery is recommended when:

  • UBCs at risk of a pathologic fracture need treatment
  • UBC is painful, growing larger or in a location that may fracture

Surgical Option #1 – The doctor may treat it by draining the cyst (aspiration) and injecting it with a steroid or with bone graft from the bone bank, supplemented occasionally with bone marrow from the person’s pelvis. This method of treatment may require more than one aspiration/injection.

Surgical Option #2 – UBC 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. Depending on the size and location of the cyst, treatment with an internal fixation device may also be needed.