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SMJ // Article

Review Article

Unicameral (Simple) Bone Cysts

Authors: Rafath Baig, MD; John L. Eady, MD

Abstract

Since their original description by Virchow, simple bone cysts have been studied repeatedly. Although these defects are not true neoplasms, simple bone cysts may create major structural defects of the humerus, femur, and os calcis. They are commonly discovered incidentally when x-rays are taken for other reasons or on presentation due to a pathologic fracture. Various treatment strategies have been employed, but the only reliable predictor of success of any treatment strategy is the age of the patient; those being older than 10 years of age heal their cysts at a higher rate than those under age 10. The goal of management is the formation of a bone that can withstand the stresses of use by the patient without evidence of continued bone destruction as determined by serial radiographic follow-up. The goal is not a normal-appearing x-ray, but a functionally stable bone.


Key Points


* Ninety-four percent of unicameral bone cysts occur in the proximal humerus and proximal femur, with the proximal humerus being affected two to three times more frequently than the proximal femur.


* The remaining 6% occur in other bones including the calcaneus (2%), ilium (2%), talus, tibia, metatarsals, fibula, ischium, pubic rami, sacrum, vertebral bodies, forearm, and craniofacial bones.


* The typical radiographic appearance is that of a lesion concentrically located in the medullary cavity of the metaphysis of a long bone with expansion in all directions, creating an expanded and thinned but unpenetrated cortex.


* The “fallen leaf” sign on plain films is virtually pathognomonic of a multiloculated bone cyst.


* Aspiration of both unicameral and aneurysmal bone cysts in children below age 10 will frequently produce blood, even with gentle aspiration pressure on the syringe.


* Rarely, simple bone cysts have been noted to cross the physis in very young patients, but this finding has been observed in older patients, as documented by MRI and injection techniques.


* The only reliable predictor of treatment success is the age of the patient; those older than 10 heal at a higher rate (90%) than those under 10 years of age (60%), no matter what treatment regimen is utilized.


* The primary goal of management is a healed bone that can withstand predictable functional stresses of activity by the patient.

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References

1. Virchow R. On the formation of bony cysts. In: Uber die Bildung von Knochencysten. Berlin, SB Akad Wiss, 1876, pp 369–381.
 
2. Baker DM. Benign unicameral bone cysts. Clin Orthop 1970;71:140–151.
 
3. Campanacci M, Campanna R, Picci P. Unicameral and aneurysmal bone cysts. Clin Orthop1986;204:25–36.
 
4. Conway WF, Hayes CW. Miscellaneous lesions of bone. Radiol Clin North Am 1993;31:339–358.
 
5. Dahlin DC. Bone Tumors, 3rd ed. Springfield, Charles C Thomas, 1978, p 371.
 
6. Jaffe H, Lichtenstein L. Solitary unicameral bone cyst. Arch Surg 1942;64:1004 –1025.
 
7. Boseker EH, Bickel WH, Dahlin DC. A clinicopathologic study of simple unicameral bone cysts. Surg Gynecol Obstet 1968;127:550–560.
 
8. Norman A, Schiffman M. Simple bone cysts: factors of age dependency. Radiology 1977;124:779–782.
 
9. Neer CSIll, Francis KC, Johnston AD, et al. Current concepts on the treatment of solitary unicameral bone cyst. Clin Orthop Relat Res 1973;97:40–51.
 
10. Monckberg G. Ueber Cystenbildung bei Osteitis Fibrosa. Verb Dtsch Ges Pathol 1904;7:232–241.
 
11. Cohen J. Etiology of simple bone cyst. J Bone Joint Surg Am 1970;52:1493–1497.
 
12. Cohen J. Simple bone cysts. Studies of cyst fluid in six cases with a theory of pathogenesis. J Bone Joint Surg Am 1960;42:609–615.
 
13. Shindell R, Huurman WW, Lippiello L, et al Prostaglandin levels in unicameral bone cysts treated by intralesional steroid injection. J Pediatr Orthop 1989;9:516–519.
 
14. Komiya S, Minamitani K, Sasaguri Y, et al. Simple bone cyst. Treatment by trepanation and studies on bone resorptive factors in cyst fluid with a theory of its pathogenesis. Clin Orthop Relat Res1993;287:204–211.
 
15. Abdelwahab IF, Hermann G, Norton KI, et al. Simple bone cysts of the pelvis in adolescents. A report of four cases. J Bone Joint Surg Am 1991;73:1090–1094.
 
16. Blumberg ML. CT of iliac unicameral bone cysts. AJR Am J Roentgenol 1981;136:1231–1232.
 
17. Hoeffel JC. Simple bone cysts of the pelvis in adolescents. A report of four cases. J Bone Joint Surg1992;74:951–952.
 
18. Smith RW, Smith CF. Solitary unicameral bone cyst of the calcaneus. A review of twenty cases. J Bone Joint Surg 1974;56:49–56.
 
19. Wu KK. A surgically treated unicameral (solitary) bone cyst of the talus with a 15-year follow-up. J Foot Ankle Surg 1993;32:242–244.
 
20. Ehara S, Rosenberg AE, el-Khoury GY. Sacral cysts with exophytic components. A report of two cases. Skeletal Radiol 1990;19:117–119.
 
21. Kragel PJ, Williams J, Garvin DF, et al. Solitary bone cyst of the radius containing Liesegang’s rings. Am J Clin Pathol 1989;92:831–833.
 
22. Matsumoto K, Fujii S, Mochizuki T, Hukuda S. Solitary bone cyst of a lumbar vertebra. A case report and review of literature. Spine 1990;15:605–607.
 
23. Nakagawa T, Kawano H, Kubota T. Solitary bone cyst of the cervical spine–case report. Neuro Med Chir (Tokyo) 1994;34:558–560.
 
24. Telfer MR, Jones GM, Pell GM, et al. Primary bone cyst of the mandibular condyle. Br J Oral Maxillofac Surg 1990;28:340–343.
 
25. Struhl A, Pritzker H, Seimon LP, et al. Solitary (unicameral) bone cyst. The fallen fragment sign revisited. Skeletal Radiol 1989;18:261–265.
 
26. Burr BA, Resnick D, Syklawer R et al. Fluid-fluid levels in a unicameral bone cyst: CT and MR findings. J Comput Assist Tomogr 1993;17:134–136.
 
27. Tillman BP, Dahlin DC, Lipscomb PR, et al. Aneurysmal bone cyst: an analysis of ninety-five cases.Mayo Clin Proc 1968;43:478–495.
 
28. Enneking WF. Simple bone cysts. In: Clinical Musculoskeletal Pathology, 3rd ed. Gainesville, University Presses of Florida, 1990, pp 281–287.
 
29. Stelling CB, Martin W, Fechner RE et al. Case report 150. Solitary bone cyst with cementum-like bone production. Skeletal Radiol 1981;621:3–215.
 
30. Adler CP. Tumour-like lesions in the femur with cementum-like material. Does a "cementoma" of long bone exist? Skeletal Radiol 1985;14:26–37.
 
31. Mirra JM, Bernard GW, Bullough PG, Johnston W, Mink G. Cementum-like bone production in solitary bone cysts. (so-called "cementoma" of long bones). Report of three cases. Electron microscopic observations supporting a synovial origin to the simple bone cyst. Clin Orthop Relat Res1978;135:295–307.
 
32. Sanerkin NG. Old fibrin coagula and their ossification in simple bone cysts. J Bone Joint Surg Br1979;61-B:194–199.
 
33. Peltier LF, Jones RH. Treatment of unicameral bone cysts by curettage and packing with plaster-of-Paris pellets. J Bone Joint Surg Am 1978;60:820–822.
 
34. Fahey JJ, O’Bnen ET. Subtotal resection and grafting in selected cases of solitary unicameral bone cyst. J Bone Joint Surg Am 1973;55:59–68.
 
35. McKay OW, Nason SS. Treatment of unicameral bone cysts by subtotal resection without grafts. J Bone Joint Surg Am 1977;59:515–519.
 
36. Spence KF, Bright RW, Fitzgerald SP, et al. Solitary unicameral bone cyst: treatment with freeze-dried crushed cortical-bone allograft. A review of one hundred and forty-four cases. J Bone Joint Surg Am 1976;58:636–641.
 
37. Scaglietti O, Marchetti PG, Bartolozzi P. The effects of methylprednisolone acetate in the treatment of bone cysts. Results of three years follow-up. J Bone Joint Surg Br 1979;61-B:200–204.
 
38. Oppenheim WL, Galleno H. Operative treatment versus steroid injection in the management of unicameral bone cysts. J Pediatr Orthop 1984;4:1–7.
 
39. Frankel SL, Chioros PD, Sidlov CJ. Steroid injection of a unicameral bone cyst of the calcaneus: literature review and two case reports. J Foot Surg 1988;27:60–65.
 
40. Goel AR, Kriger J. Unicameral bone cysts: treatment with methylprednisone acetate injections. J Foot Ankle Surg 1993;32:242–244.
 
41. Moreau G, Letts M. Unicameral bone cyst of the calcaneus in children. J PediatrOrthop1994;14:101–104.
 
42. Wilkins RM. Unicameral bone cysts. J Am Acad Orthop Surg 2000;8:217–224.
 
43. Inoue O, Ibaraki K, Shimabukuro H, et al. Packing with high-porosity hydroxyapatite cubes alone for the treatment of simple bone cyst. Clin Othop 1993;293:287–292.
 
44. Altermatt S, Schwobel M, Pochon JP. Operative treatment of solitary bone cysts with tricalcium phosphate ceramic. A 1 to 7 year follow-up. Eur J Pediatr Surg 1992;2:180–182.