title: Simple bone cysts: better with age?
abstract: OBJECTIVE
  The purpose of this study was to evaluate whether simple bone cysts (SBC) resolve with age.
  
  
  METHODS
  Twenty four subjects with SBC who participated in a prior randomized clinical trial but had not healed at trial conclusion were evaluated for cyst healing. The following clinical and radiographic data were evaluated: age, sex, pain (Visual Analogue Scale), functional health (Short Form 36), subsequent fracture, involved bone, cyst area (cm), distance from physis (cm), endosteal thickening (yes/no), scalloping (no new scalloping/new scalloping), opacity/radiolucency (as is), loculation (yes/no), trabeculation (yes/no), tubulation (yes/no), transition zone (sharp/wide), geographic borders (geographic nonpermeative/nongeographic permeative), radiodense rim (>50%/no rim), and growth plate status (open/closed). Cyst healing was graded as: 1-cyst clearly visible; 2-cyst visible but multilocular and opaque; 3-sclerosis around or within a partially visible cyst; or 4-complete healing with obliteration of cyst. Healing was defined as grade 4.
  
  
  RESULTS
  Of 24 subjects, 15 (63%) were male, 18 (75%) cysts were located in the humerus, and 4 (25%) in the femur. Patients were followed for 7.0±1.0 years following initial treatment with a mean age at follow-up of 17.2±3.2 years and 14 (87%) of growth plates were closed. Pain was minimal (0.6/10), function was high (91/100), and none of the patients had experienced subsequent fractures. Although distance from physeal scar had increased (P<0.0001), cyst area reduction (P<0.1) and overall cyst healing (P<0.2) had not changed. Of the 24 subjects, none were graded as healed at time of follow-up. Of the remaining radiographic variables, only decreased loculation (P<0.02) and increased endosteal thickening (P<0.04) showed significant changes.
  
  
  CONCLUSIONS
  Despite the assumption that most SBC will resolve with skeletal maturity, this study indicates that none of the cysts were graded as completely healed although 87% of growth plates were closed.
  
  
  CONCLUSIONS
  Growth plate closure may not signify healing of SBC and although symptoms and fractures are rare, further studies are needed to follow patients with SBC through early adulthood.
authors.affiliation: *Department of Surgery, The Hospital for Sick Children †Department of Surgery, Division of Orthopaedic Surgery ‡Departments of Public Health Sciences, and Health Policy, Management and Evaluations, University of Toronto, Toronto, ON, Canada.
authors.forename: Sandra
authors.initials: S
authors.lastname: Donaldson
authors.forename: James G
authors.initials: JG
authors.lastname: Wright
mesh_terms: D000293:Adolescent; D001845:Bone Cysts / Q000150:complications / Q000000981:diagnostic imaging / Q000503:physiopathology; D001861:Bone Regeneration; D005260:Female; D005269:Femur / Q000000981:diagnostic imaging / Q000503:physiopathology; D006132:Growth Plate / Q000000981:diagnostic imaging; D006801:Humans; D006811:Humerus / Q000000981:diagnostic imaging / Q000503:physiopathology; D008297:Male; D010146:Pain / Q000209:etiology*; D063868:Patient Outcome Assessment; D011859:Radiography; D013995:Time; D055815:Young Adult