(P 39) PATIENT OUTCOMES FOLLOWING MINIMALLY INVASIVE TREATMENT OF ANEURYSMAL BONE CYSTS USING DOXYCYCLINE

Objective: Aneurysmal bone cysts (ABC) are aggressive benign neoplasms usually seen in the first three decades of life. Treatment of these lesions can be challenging due to a high rate of reoccurrence and localized destruction of the surrounding bone and often soft tissue as these lesions can rapidly expand. Traditional treatments have included wide local excision and intralesional curettage with physical adjuvants such as cryoablation to obtain local control. These open procedures can potentially lead to significant blood loss due to the highly vascular nature of these lesions. Recently, doxycycline injection has been proposed as an alternative method of treatment. Doxycycline acts as an inhibitor of metalloproteinases and VEGF, and as a sclerosing agent. We reported our multi-institution single surgeon experience with this method of treatment.

Methods: We retrospectively reviewed records of patients who underwent doxycycline injection for aneurysmal bone cysts in 2 urban hospitals by one orthopedic oncology surgeon from 2019 to 2023. One patient was lost during the follow up and excluded from the study. Fourteen patients completed follow up. One of two surgical techniques was performed for these patients. Patients with distal lesions that were amenable to treatment under tourniquet underwent a minimal corticotomy of the cavity with curettage of the lesion prior to instillation of doxycycline/albumin colloid and demineralized bone matrix (Synthes DBX) into the cavity. More proximal lesions particularly around the pelvis were treated with a percutaneous method using a large diameter bone marrow needle for aspiration and injection of the doxycycline albumen colloid. Treatment response was evaluated clinically by complete resolution of symptoms and radiographically by resolution of lytic component and measuring the thickness of involved cortex. Recurrence was indicated by expansion of lytic areas after completion of treatment.

Results: Sixty-two percent of patients were female (n=9). The median age of patients was 14 (range 7-34). The presenting symptoms were pain 64% (9 cases), 3 pathologic fractures (21%), one presented as a mass (7%), and one was an incidental finding (7%). The lesion locations were pelvis 29% (4 cases), upper extremity 35% (5 cases), and lower extremity 35% (5 cases). Median follow up was 8.5 months (range 2-22 months). Median time of presentation to surgery was 3 months (2 weeks to 12 months range). 11 patients (65%) were initially treated with minimal corticotomy with curettage prior to doxycycline injection and 6 (35%) were treated with percutaneous injection alone. One patient initially treated with curettage and doxycycline had disease recurrence and was subsequently treated with percutaneous doxycycline. One patient initially treated with percutaneous doxycycline had disease recurrence which was treated with curettage and doxycycline. Median time between surgery and clinical full improvement was 1.5 months (range 1-2 months). Median time between surgery and radiographic improvement was 7.5 months (range 1.5 to 10 months). 2 patients needed re-operation (14%). One was treated with repeat injection and one with curettage, cryosurgery, and cementation.

Conclusion: Minimally invasive treatment of ABC using a doxycycline albumen colloid provides satisfactory clinical and radiologic outcomes with a low recurrence rate similar to more aggressive open approaches that have historically been used for this aggressive disease. Significant regression of protuberant lesions was observed even with percutaneous treatment. This approach may help to reduce blood loss and surgical morbidity in patients that are often young and skeletally immature.