Massive osteoarticular knee allografts: structural changes evaluated with CT.
OBJECTIVE
To analyze the structural changes seen at computed tomography (CT), particularly the findings that precede insufficiency (fatigue) fractures in massive osteoarticular knee allografts.


METHODS
The subchondral and cancellous bone of 12 allografts were retrospectively evaluated with repeat transaxial CT (mean follow-up, 53 months).


RESULTS
Early cortical graft resorption was followed by slow thickening after 6 months. Formation of resorptive cysts increased the cortical irregularity, which leveled off after 2 years. Late remodeling was evident as a subcortical sclerotic rim, "neocortex." Initially, the cancellous graft bone showed higher attenuation than the host bone; this difference subsided gradually during the first 3 years. Four insufficiency fractures were detected after the 1st postoperative year. Poor remodeling preceded these fractures.


CONCLUSIONS
CT effectively depicted the structural changes during allograft incorporation and was superior to plain radiography for the detection of insufficiency fractures. The use of CT for follow-up of massive osteoarticular knee allografts provides additional information concerning the readiness of the graft for weight bearing.
Mattila
K T
KT
Department of Diagnostic Radiology, University of Turku, Finland.
Heikkila
J T
JT
Aho
A J
AJ
Manner
I K
IK
Dean
P B
PB
D000293:Adolescent; D000328:Adult; D001845:Bone Cysts / Q000000981:diagnostic imaging; D016723:Bone Remodeling; D001862:Bone Resorption / Q000000981:diagnostic imaging; D016025:Bone Transplantation / Q000000981:diagnostic imaging*; D002356:Cartilage / Q000000981:diagnostic imaging* / Q000637:transplantation*; D005260:Female; D005500:Follow-Up Studies; D015775:Fractures, Stress / Q000000981:diagnostic imaging; D006801:Humans; D007719:Knee Joint / Q000000981:diagnostic imaging* / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D010026:Osteosclerosis / Q000000981:diagnostic imaging; D012189:Retrospective Studies; D013997:Time Factors; D014057:Tomography, X-Ray Computed; D014184:Transplantation, Homologous; D016474:Weight-Bearing