Characteristics of degeneration in an unstable knee with a coronal surface step-off.
To investigate the effect of instability on the remodelling of a minor articular surface offset, we created a 0.5 mm coronal step-off of the medial femoral condyle in 12 New Zealand white rabbits and transected the anterior cruciate ligament (ACL). A control group of 12 rabbits had only ACL resection and the opposite knee was used as the non-operated control. The osteoarthritic changes at 6, 12 and 24 weeks after surgery were evaluated histologically. In addition, changes in the immunological detection of 3-B-3(-) and 7-D-4 chondroitin-6-sulphate epitopes were determined because of the previous association of such changes with repair of cartilage and early osteoarthritis. In the instability/step-off group there was rapidly progressing focal degeneration of cartilage on the high side of the defect, not seen in previous step-off studies in stable knees. The rest of the femoral condyles and the tibial plateaux of the instability/step-off group had moderate osteoarthritis similar to that of the instability group. 3-B-3(-) was detectable in the early and the intermediate stages of osteoarthritis but no staining was seen in the severely damaged cartilage zones. Immunoreactivity with 7-D-4 increased as degeneration progressed.
Lovász
G
G
Orthopaedic Hospital, Los Angeles, California 90007, USA.
Park
S H
SH
Ebramzadeh
E
E
Benya
P D
PD
Llinás
A
A
Bellyei
A
A
Luck
J V
JV
Sarmiento
A
A
D000818:Animals; D016118:Anterior Cruciate Ligament / Q000601:surgery; D002358:Cartilage, Articular / Q000473:pathology*; D005260:Female; D007593:Joint Instability / Q000473:pathology*; D011817:Rabbits; D013978:Tibial Fractures / Q000473:pathology