Predicting Blood Loss in Aneurysmal Bone Cyst Surgery

Background: Preoperative estimation of intraoperative blood loss is essential for its management and literature is lacking with respect to factors influencing blood loss in aneurysmal bone cysts (ABC) surgery. The purpose of this study is to identify risk factors and predictors for blood loss in ABC surgery.

Methods: An IRB-approved retrospective review was performed from 2011 to 2021 at a pediatric tertiary care center. A database identified pediatric patients (<18y old) undergoing surgical curettage and bone grafting for ABC. Lesions in the skull and ribs were excluded. Data collected included demographic data (age, sex), Enneking stage, Capanna type for limb lesions, lesion location, lesion volume (calculated as Transverse × Craniocaudal × Anteroposterior), and history of pathologic fracture before surgical management. Blood loss was recorded as (1) absolute blood loss during surgery and (2) relative loss of total blood volume for individual patients based on their weight and age. Statistical testing was performed using bivariate statistics (Mann-Whitney, Kruskal-Wallis) and multivariate regression analysis.

Results: We identified a total of 102 lesions in 101 patients with a mean age of 11.5 years at the time of surgery (range 1.0 to 18.2). Absolute blood loss and relative blood loss increased significantly (P<0.001 for both) with respect to lesion volume. Risk factors for absolute and relative blood loss were identified as type 3 Enneking lesions and those located at the spine/pelvis for all lesions (P<0.05), while for lesions in the limbs, those located in the shoulder/hip were identified as a risk factor for both absolute and relative blood loss. In multivariate analysis, age, lesion location, and lesional volume were predictive of absolute blood loss (P<0.05). While multivariate analysis for relative blood loss identified lesion location and lesional volume of >100 mm3 (P=0.004) as predictors.

Conclusion: Our study enhances the understanding of intraoperative blood loss in ABC surgery. Findings from this study help identify patients at risk of increased blood loss. Age and lesion volume are factors to consider before estimating blood loss in ABC surgery. Surgeons should be cautious of bleeding risk associated with enneking type 3 lesions, spine/pelvic lesions, and locations precluding the use of a tourniquet.

Level of evidence: Level III.