Site-dependent changes in structure and function of lapine articular cartilage 4 weeks after anterior cruciate ligament transection.
OBJECTIVE
The aim of this study was to investigate the site-dependent changes in the structure and function of articular cartilage in the lapine knee joint at a very early stage of osteoarthritis (OA), created experimentally by anterior cruciate ligament transection (ACLT).


METHODS
Unilateral ACLT was performed in eight mature New Zealand white rabbits. ACL transected and contralateral (C-L) joints were prepared for analysis at 4 weeks after ACLT. Three rabbits with intact joints were used as a control group (CNTRL). Femoral groove, medial and lateral femoral condyles, and tibial plateaus were harvested and used in the analysis. Biomechanical tests, microscopy and spectroscopy were used to determine the biomechanical properties, composition and structure of the samples. A linear mixed model was chosen for statistical comparisons between the groups.


RESULTS
As a result of ACLT, the equilibrium and dynamic moduli were decreased primarily in the femoral condyle cartilage. Up to three times lower moduli (P < 0.05) were observed in the ACLT group compared to the control group. Significant (P < 0.05) proteoglycan (PG) loss in the ACLT joint cartilage was observed up to a depth of 20-30% from the cartilage surface in femoral condyles, while significant PG loss was confined to more superficial regions in tibial plateaus and femoral groove. The collagen orientation angle was increased (P < 0.05) up to a cartilage depth of 60% by ACLT in the lateral femoral condyle, while smaller effects, but still significant, were observed at other locations. The collagen content was increased (P < 0.05) in the middle and deep zones of the ACLT group compared to the control group samples, especially in the lateral femoral condyle.


CONCLUSIONS
Femoral condyle cartilage experienced the greatest structural and mechanical alterations in very early OA, as produced by ACLT. Degenerative alterations were observed especially in the superficial collagen fiber organization and PG content, while the collagen content was increased in the deep tissue of femoral condyle cartilage. The current findings provide novel information of the early stages of OA in different locations of the knee joint.
Department of Applied Physics, University of Eastern Finland, Kuopio, Finland. Electronic address: Janne.Makela@uef.fi.
J T A
JT
Mäkelä
Department of Applied Physics, University of Eastern Finland, Kuopio, Finland; Department of Physical Therapy, Faculty of Rehabilitation Sciences, Isfahan University of Medical Sciences, Isfahan, Iran; Department of Physical Therapy, School of Medical Sciences, Tarbiat Modares University, Tehran, Iran.
Z S
ZS
Rezaeian
Department of Applied Physics, University of Eastern Finland, Kuopio, Finland.
S
S
Mikkonen
Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada.
R
R
Madden
Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada; Advanced Biomedical and Welfare Technology R&BD Group, Korea Institute of Industrial Technology, Cheonan-si, Chungcheongnam-do, Korea.
S-K
SK
Han
Department of Applied Physics, University of Eastern Finland, Kuopio, Finland.
J S
JS
Jurvelin
Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada.
W
W
Herzog
Department of Applied Physics, University of Eastern Finland, Kuopio, Finland.
R K
RK
Korhonen
D000704:Analysis of Variance; D000818:Animals; D016118:Anterior Cruciate Ligament / Q000601:surgery*; D000070598:Anterior Cruciate Ligament Injuries; D001169:Arthritis, Experimental; D001696:Biomechanical Phenomena; D002358:Cartilage, Articular / Q000378:metabolism* / Q000473:pathology*; D003094:Collagen / Q000378:metabolism*; D016001:Confidence Intervals; D004195:Disease Models, Animal; D005260:Female; D007719:Knee Joint / Q000473:pathology* / Q000503:physiopathology / Q000601:surgery; D011509:Proteoglycans / Q000378:metabolism*; D011817:Rabbits; D011897:Random Allocation; D012680:Sensitivity and Specificity; D013314:Stress, Mechanical
D011509:Proteoglycans; D003094:Collagen
Anterior cruciate ligament transection; Articular cartilage; Knee; Lapine; Osteoarthritis