Osteosarcoma near joints: assessment and implications.
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.
Quan
Gerald M Y
GM
Department of Orthopaedics, St. Vincent's Hospital, Melbourne, Australia.
Slavin
John L
JL
Schlicht
Stephen M
SM
Smith
Peter J
PJ
Powell
Gerard J
GJ
Choong
Peter F M
PF
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