title: Osteosarcoma near joints: assessment and implications.
abstract: BACKGROUND
  The choice of performing surgery when tumors encroach onto joints remains a challenging and controversial issue. Pre-operative assessment by magnetic resonance imaging (MRI) is of critical importance in dictating surgical management and subsequent functional outcome.
  
  
  METHODS
  We examined archival samples from 27 patients with osteosarcoma, adjacent to synovial joints for the incidence and mechanism of osteosarcoma extension into the joint space. Histopathologic findings were correlated with pre-operative MRI findings and choice of operation.
  
  
  RESULTS
  There was no evidence of penetration across the entire thickness of articular cartilage into the joint cavity in all of the 27 cases. When pre-operative MRI confidently excluded joint involvement by tumor, enabling an intra-articular surgical approach, histopathologic correlation confirmed the absence of joint involvement in all cases. The low incidence of joint involvement was despite the presence of extensive bone and soft tissue involvement in most cases, a tendency for peripheral extension of tumor around the articular margin of the bone, and evidence of joint effusions pre-operatively in more than one-third of cases.
  
  
  CONCLUSIONS
  Joint involvement by osteosarcoma is uncommon, with articular cartilage being a relative barrier to tumor invasion. If pre-operative MRI does not show definite evidence of intra-articular tumor involvement, it is likely to be safe to proceed with intra-articular resection.
authors.affiliation: Department of Orthopaedics, St. Vincent's Hospital, Melbourne, Australia.
authors.forename: Gerald M Y
authors.initials: GM
authors.lastname: Quan
authors.forename: John L
authors.initials: JL
authors.lastname: Slavin
authors.forename: Stephen M
authors.initials: SM
authors.lastname: Schlicht
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Smith
authors.forename: Gerard J
authors.initials: GJ
authors.lastname: Powell
authors.forename: Peter F M
authors.initials: PF
authors.lastname: Choong
mesh_terms: D000293:Adolescent; D000328:Adult; D001859:Bone Neoplasms / Q000473:pathology* / Q000601:surgery; D005260:Female; D006801:Humans; D017746:Joint Capsule / Q000473:pathology*; D007596:Joints / Q000473:pathology*; D007719:Knee Joint / Q000473:pathology; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D012516:Osteosarcoma / Q000473:pathology* / Q000601:surgery; D011300:Preoperative Care; D012189:Retrospective Studies