Open surgical treatment of unicameral bone cysts : A retrospective data analysis.

Background: A variety of treatment options for unicameral bone cysts (UBC) exist. The controversy of open management of UBC is discussed. The aim of this study was to analyze a single institution's experience in the open surgical treatment of UBC.

Patients and methods: By retrospective analysis of the Vienna Bone and Soft Tissue Tumor Registry, 119 patients with open surgery and histologically verified UBC with a mean follow up of 4.8 years (range 1-30 years) were included. Lesion treatment failure was defined as surgically addressed UBC undergoing revision surgery due to persistence or recurrence.

Results: Local revision-free survival for lesion treatment failure was 93% after 1 year, 80% after 2 years, 60% after 5 years and 57% after 10 years. Of the patients 34 (29%) had at least 1 revision surgery due to lesion treatment failure. We found that patients with lesion treatment failure were younger (p = 0.03), had UBC with less minimal distance to the growth plate (p = 0.02) and more septation chambers in radiologic imaging (p = 0.02). Patients with open revision surgery were less likely to require a second revision due to lesion treatment failure than patients with percutaneous revision surgery (p = 0.03).

Conclusion: Open surgery for UBC can only be recommended as reserve treatment in younger children with actively growing lesions. Open UBC surgery carries a relatively high risk of almost 30% of lesion treatment failure and therefore the indications should be limited to extensive osteolysis with high risk of pathological fractures, lesions with displaced pathological fractures, and lesions with an ambiguous radiological presentation that require tissue collection.