Unicameral (simple) bone cysts are benign bone lesions usually observed in the pediatric or adolescent population. They are located near growth plates and most commonly occur in the proximal humerus (arm bone) or proximal femur (thigh bone). A unicameral bone cyst is described as a fluid-filled cyst centrally located in the bone with cortical thinning. These cysts are usually asymptomatic until fracture occurs. Following fracture healing, the cysts do not typically resolve on their own until possibly later with skeletal maturity. Treatment is necessary for larger cysts and in weight bearing bones to decrease risk of fracture, permanent deformity, or decreased function. Depending on the size and location of the cyst, treatment options range from injecting demineralized bone matrix (sterilized donor bone) to bone grafting with internal fixation. This condition does have a high recurrence rate but typically resolves when the patient has reached skeletal maturity.
Depending on the size, location, and risk of fracture, treatment options may vary. If the cyst is stable, conservative treatment is recommended and the patient is monitored regularly with follow up X-rays. If the cyst becomes symptomatic or if fracture has already occurred, more significant treatment is warranted. For large cysts, a limited incision is made to expose the location of the cyst. Dr Chudik will then drain the fluid from the cyst and scrape out the associated bone to remove the cyst in its entirety. The space is then filled with bone graft. In some cases, a plate or screws are also used to stabilize the healing bone to minimize the risk for fracture.
The outlook following treatment of unicameral bone cysts is very good. Most of these cysts are treated successfully or will resolve on their own once the patient has reached skeletal maturity.