Do’s and Don’ts in Primary Aneurysmal Bone Cysts of the Proximal Femur in Children and Adolescents: Retrospective Multicenter EPOS Study of 79 Patients

Abstract

Background: Aneurysmal bone cysts (ABC) are rare benign cystic bone tumors, generally diagnosed in children and adolescents. Proximal femoral ABCs may require specific treatment strategies because of an increased pathologic fracture risk. As few reports are published on ABCs, specifically for this localization, consensus regarding optimal treatment is lacking. We present a large retrospective study on the treatment of pediatric proximal femoral ABCs. Methods: All eligible pediatric patients with proximal femoral ABC were included, from 11 tertiary referral centers for musculo-skeletal oncology (2000-2021). Patient demographics, diagnostics, treatments, and complications were evaluated. Index procedures were categorized as percutaneous/open procedures and osteosynthesis alone. Primary outcomes were: time until full weight-bearing and failure-free survival. Failure was defined as open procedure after primary surgery, >3 percutaneous procedures, recurrence, and/or fracture. Risk factors for failure were evaluated. Results: Seventy-nine patients with ABC were included [mean age, 10.2 (±SD4.0) y, n=56 male]. The median follow-up was 5.1 years (interquartile ranges=2.5 to 8.8). Index procedure was percutaneous procedure (n=22), open procedure (n=35), or osteosynthesis alone (n=22). The median time until full weight-bearing was 13 weeks [95% confidence interval (CI)=7.9-18.1] for open procedures, 9 weeks (95% CI=1.4-16.6) for percutaneous, and 6 weeks (95% CI=4.3-7.7) for osteosynthesis alone (P=0.1). Failure rates were 41%, 43%, and 36%, respectively. Overall, 2 and 5-year failure-free survival was 69.6% (95% CI=59.2-80.0) and 54.5% (95% CI=41.6-67.4), respectively. Risk factors associated with failure were age younger than 10 years [hazard ratios (HR)=2.9, 95% CI=1.4-5.8], cyst volume >55 cm3 (HR=1.7, 95% CI=0.8-2.5), and fracture at diagnosis (HR=1.4, 95% CI=0.7-3.3). Conclusions: As both open and percutaneous procedures along with osteosynthesis alone seem viable treatment options in this weight-bearing location, optimal treatment for proximal femoral ABCs remains unclear. The aim of the treatment was to achieve local cyst control while minimizing complications and ensuring that children can continue their normal activities as soon as possible. A personalized balance should be maintained between undertreatment, with potentially higher risks of pathologic fractures, prolonged periods of partial weight-bearing, or recurrences, versus overtreatment with large surgical procedures, and associated risks. Level of Evidence: Level IV, therapeutic study.

Stabilisation of Pathologic Proximal Femoral Fracture near the Growth Plate with Use of a Locking Plate and Transphyseal Screws

“…The authors identified “numerous forms of therapy” independent of localisation, including curettage and radiation but no stabilisation techniques. In the recently published retrospective multicentre EPOS study, in which 79 patients with ABC on the proximal femur were examined, no detailed information on the selection of the osteosynthesis technique, especially in the immediate vicinity of the growth plate, was provided [ 19 ]. The transphyseal screws we used were also not mentioned.…”

“…As an open procedure was chosen by 43% of our respondents and 44% of the participants of the EPOS multicentre study [ 19 ], in our opinion, there is nothing to be said against a plate osteosynthesis, which does not significantly exceed the extent of the intervention. From our point of view, immobilisation using an HSC offers, at best, an alternative if the procedure is not open.…”

The treatment of aneurysmal bone cysts

“…Many sclerotherapies have been described with different sclerosants and application techniques. Some like sodium tetradecyl sulfate are injected with air to create a foam [ 25 ▪ ], while others like polidocanol are injected as liquids [ 5 ▪▪ ]. Sometimes combinations with embolizing substances are administered, aiming for increasing safety [ 26 ▪▪ ].…”

“…Spinal lesions in general have received a substantial amount of interest recently, with multiple studies showing effectiveness of sclerotherapy in this vulnerable anatomical location [ 25 ▪ ]. In their cervical spine ABC series, Wong et al reported one treatment-related complication after doxycycline injection in a C2 ABC leading to sclerotherapy triggered spasm of the right posterior inferior cerebellar artery, resulting in distribution area infarction [ 31 ].…”

Surgical outcomes of proximal femoral bone cysts in pediatric patients: a retrospective study of 41 cases

“…The primary sites of manifestation are the proximal humerus and femur ( 1 ). Treatment objectives for these cysts include preventing pathologic fractures, promoting healing, and minimizing recurrence ( 2 ). Currently, strategies to promote cyst healing encompass a range of interventions, including steroid injections, curettage and grafting, internal fixation, or a combination thereof.…”