This narrative review synthesizes current knowledge on unicameral bone cysts (UBCs), covering epidemiology, pathogenesis, imaging diagnosis, and treatment options. It addresses a clinically common benign pediatric bone lesion where treatment choice remains controversial and recurrence rates vary widely by technique.
A child under 10 presenting with a lytic proximal humeral or femoral lesion after minor trauma needs a UBC on the differential immediately. The key management question is fracture risk: if the cyst spans more than 85% of the bone's diameter or the wall is under 0.5 mm, operative intervention is warranted rather than observation.
For most UBCs without high fracture risk, observation is appropriate — most resolve by skeletal maturity. When treatment is needed, flexible intramedullary nailing (with or without demineralized bone matrix) is now the preferred approach, offering 73-77% healing with recurrence under 10%, far outperforming steroid injection or curettage alone.
Proximal femur UBCs deserve special attention: pathologic fracture here risks varus malunion, osteonecrosis, and physeal arrest. A different risk profile than the proximal humerus, where even pathologic fractures can often be managed nonoperatively.
The active (within 1 cm of physis) vs. Latent (diaphyseal) classification shapes prognosis: active cysts in young children recur at four times the rate of latent cysts in adolescents, so close follow-up and lower threshold for intervention apply.
This narrative review synthesizes current knowledge on unicameral bone cysts (UBCs), covering epidemiology, pathogenesis, imaging diagnosis, and treatment options. It addresses a clinically common benign pediatric bone lesion where treatment choice remains controversial and recurrence rates vary widely by technique.
A child under 10 presenting with a lytic proximal humeral or femoral lesion after minor trauma needs a UBC on the differential immediately. The key management question is fracture risk: if the cyst spans more than 85% of the bone's diameter or the wall is under 0.5 mm, operative intervention is warranted rather than observation.
For most UBCs without high fracture risk, observation is appropriate — most resolve by skeletal maturity. When treatment is needed, flexible intramedullary nailing (with or without demineralized bone matrix) is now the preferred approach, offering 73-77% healing with recurrence under 10%, far outperforming steroid injection or curettage alone.
Proximal femur UBCs deserve special attention: pathologic fracture here risks varus malunion, osteonecrosis, and physeal arrest. A different risk profile than the proximal humerus, where even pathologic fractures can often be managed nonoperatively.
The active (within 1 cm of physis) vs. Latent (diaphyseal) classification shapes prognosis: active cysts in young children recur at four times the rate of latent cysts in adolescents, so close follow-up and lower threshold for intervention apply.