Aneurysmal Bone Cyst


ABC Proximal HumerusABC Distal Femur




Expansile pseudotumor of reactive hemorrhagic tissue arising in bone


Characterised by blood filled spaces separated by fibrous tissue




Metaphysis of long bones

- proximal humerus

- femur

- tibia


Posterior elements of vertebra





- 80% occur in 10-20 year range

- mean age 14 years


Female >Male






Pathological fracture


Natural history


Pathological fracture rare

May resolve with fracture or skeletal maturity




Primary 50%

- arise de novo 


Oliveira et al Am J Pathol 2004

- rearrangements of USP6 and/or CDH11 genes in 70% of cases

- absent in secondary ABC


Secondary / ABC like areas in other tumors 50%

- probably secondary to haemorrhage into primary tumour

- Giant cell tumour / chondroblastoma / osteoblastoma / osteosarcoma

- treat as underlying primary tumor




Multi-loculated expansile lesion with cortical thickening

Often fail to make definitive diagnosis on xray


ABC humerusABC ankleABC fibula




Usually difficult to determine UBC from ABC

- cystic lesions

- haemosiderin content - low to intermediate signal on T1 and T2

- borders and septae enhance with contrast


Gruenewald et al Br J Radiol 2023

- 36 patients with UBC or ABC

- fluid fluid levels / septation seen in both on MRI

- arterial feeders on MRA helped differentiate some ABC's


ABC ankle mri 1ABC ankle MRI 2ABC distal femur MRI


Fluid - Fluid levels 

- due to sedimentation of RBC's & serum within the cavities

- patient must remain motionless for 10 minutes prior to the scan being performed

- allows time for sedimentation

- can also be seen in UBC


 ABC MRI fluid fluid levelsMRI ABC distal femur




ABC CT ankle


ABC clavicleABC clavicle CT

ABC medial clavicle


Bone Scan


Usually increased uptake

Exclude polyostotic disease




Fibrous dysplasia / GCT / Unicameral Bone Cyst / Infection / Osteosarcoma




Gross pathology


Blood filled spaces with fibrous septa





- haemosiderin-laden macrophages

- multinucleated giant cells



- fibrous stroma

- small amounts of osteoid



- USP6 rearrangements

- no expression of H3G34W (GCT)
- no expression of H3K36M (chondroblastoma)

- no expression of SATB2 (osteosarcoma)




Nonoperative Management




Avoid contact sports


Interventional radiology




Injection of demineralized bone matrix / bone marrow




Cruz et al Eur J Orthop Surg Traumatol 2021

- systematic review comparing sclerotherapy to embolization

- 13 studies with 416 patients

- recurrence embolization 19%

- recurrence sclerotherapy 6%




Rai et al J Orthop 2022

- injection of sequential intralesional percutaneous polidocanol in 43 patients

- complete resolution in 37/43 at one year, and 43/43 at two years


Rastogi et al JBJS Br 2006

- 72 patients with ABC with mean age 15

- treated with percutaneous intralesional 3% polidocanol

- average number of injections of 3 (range, 1 - 5)

- 10/72 patients cured with single injection

- 2/72 (3%) had recurrence at 2 years, successfully treated again with sclerotherapy


Selective Arterial Embolisation



- difficult to reach locations

- spine / pubis / sacrum




Rossi et al Int Orthop 2017

- 102 cases of ABC treated with arterial embolization with 7 years follow up

- feasible in 88 (86%) of patients with a feeding artery

- overall 82% success

- successful in 57% with one embolization, 19% two embolizations, 6% three embolizations

- 18% recur and require surgical intervention


Autogenous bone marrow / Demineralized bone matrix


Docquier et al JBJS Am 2005

- 13 aneurysmal bone cysts

- small incision

- injection of demineralized bone and autologous bone marrow

- healing in 11/13


Andreani et al Stem Cells Int 2020

- 42 ABCs treated with injection of BMC (bone marrow concentrate)

- 32/42 healed with 1 injection

- 7/10 healed with second injection

- 2/3 healed with third injection


Operative Management




Failure minimally invasive treatment

Joint space threatened

Weight bearing joints




Currettage and bone graft

Currettage / bone graft / fixation

Allograft / Joint Replacement




Strohm et al Eur J Trauma Emerg Surg 2023

- meta-analysis of 163 studies

- currettage had 91% healing and 22% recurrence

- currettage and autologous cancellous bone graft had 96% healing and 15% recurrence


Lin et al CORR 2008

- case series 53 patients

- closer to physis = higher recurrence rate


Currettage and bone grafting




Must be able to preserve articular surface




Full and careful curettage

- intra-lesional treatment

- need to burr away all of lesion

- must take care as bone very thin

- areas of fracture not uncommon

- must beware growth plates in skeletally immature

- supplement with bone graft / bone marrow aspirate / PMMA


ABC ankleABC CT ankleABC ankle bone graft ORIF




Cevolani et al J Tissue Eng Regen Med 2021

- 239 patients treated with curettage and bone graft

- healing in 177/239 (74%) at 42 months


Syvanen et al Scand J Surg 2018

- 18 cases treated with curettage and bioactive glass

- 2/18 (11%) recurrence


Currettage / Bone graft / Fixation


ABC Currettage and Bone GraftingABC Bone Grafting


ABC Grade 3ABC Grade 3 Bulk Structural Allograft


Resection and arthroplasty




Articular cartilage not salvageable