Unicameral bone cyst: radiographic assessment of venous outflow by cystography as a prognostic index

J Pediatr Orthop B. 2012 Nov;21(6):489-94. doi: 10.1097/BPB.0b013e328355e5ba.


The aim of this study was to determine the benefits of cystography in the management of a simple bone cyst, its implication in the final result of the treatment after corticoid intracystic injections, and the presence of secondary effects. We retrospectively reviewed 42 patients diagnosed with a simple bone cyst. Cystography was performed before the corticoid injection. The presence or absence of loculation intracyst and the existence and number of venous outflows were determined. According to the venous drainage, cysts were classified as type 0 when a venous outflow did not exist and as type 1 when there was a rapid venous outflow (<3 min). The treatment protocol included a maximum of three corticoid injections at an interval of 6 months. Healing of the cyst was determined on the basis of Neer's criteria. Secondary effects and surgical complications were assessed. Cystography studies showed a unicameral bone cyst with absent loculation in 16 cases (37.3%), whereas the lesion showed multiloculation in 26 cases (62.7%). There was no statistical difference between loculation intracyst (present or absent) and the final outcomes of the 42 cysts treated with a steroid injection (P=0.9). Cystography showed a negative venogram in 10 cases (23.8%), whereas the cysts showed a rapid venous outflow in 32 cases (76.2%). On the basis of Neer's classification, all patients with a negative venogram achieved complete healing of the cyst. Patients with a rapid venous outflow achieved complete healing in 14 cases (Neer I). In two patients, the healing was incomplete at the end of the follow-up period (Neer IV). In most cases (21 cysts), healing was partial (Neer II). Five patients showed a recurrence after initial healing of the cyst (Neer III) (P<0.05). The number or the size of veins did not affect healing of a bone cyst (P=0.6). Two patients with a rapid venous outflow showed a generalized hypertrichosis after the first injection of corticosteroids. Sex and age at the initiation of the first injection were not significant factors of healing (P=0.4). The average follow-up time was 59 months (24-60 months). Cystography provides morphological and functional information of simple bone cyst. It is a useful test before the administration of percutaneous injections of sclerosing substances. It facilitates the differentiation of cysts that may achieve complete healing (negative venogram) from those that tend to show recurrence (rapid venous outflow). Therapeutic material should be introduced slowly and a second trocar should always be placed to decrease the risk of migration in cysts with communication with the venous system.

MeSH terms

  • Adolescent
  • Bone Cysts / blood supply*
  • Bone Cysts / diagnosis*
  • Bone Cysts / drug therapy
  • Child
  • Child, Preschool
  • Female
  • Glucocorticoids / administration & dosage
  • Glucocorticoids / therapeutic use
  • Humans
  • Injections, Intralesional
  • Male
  • Phlebography / methods*
  • Prognosis
  • Regional Blood Flow
  • Retrospective Studies
  • Treatment Outcome
  • Veins / pathology*
  • Veins / physiopathology


  • Glucocorticoids