Fig 1.
A) Diagram of selected locations on tibial plateau for Mankin’s score and CZC measurements.
Showing here is a lateral tibial plateau, where standardized areas are defined in the evenly divided three portions of the plateau: peripheral portion, near the edge of the plateau; the central portion, in the middle of the plateau; and the medial portion, close to the cruciate ligaments. Three areas are defined in the same way on the medial plateau (bar = 50μm). B) CZC measurements, using ImageJ. The tidemark was traced for true length (L, white arrows). The straight line (black arrows) was drawn, as L0, for calculation of tidemark roughness. The cement line between CZC and subchondral bone was also traced (open arrows) for measurements of CZC area between the tidemark and cement line (bar = 20μm).
Fig 2.
A, B and C are the peripheral, central and medial regions of the medial plateau in the control knees. D, E, and F are the peripheral, central and medial regions of the medial plateau of the PTOA knees, respectively. While the cartilage in the control knees is intact and uniformly stained for extracellular matrix, the cartilage in the PTOA joints shows clustering cells, decreased and uneven staining of proteoglycans, and surface fibrillation (Safranin-O/Fast green/Hematoxylin staining). B) Mankin’s scores of six selected locations on the tibial plateau of the PTOA and control knees. PTOA developed in all three locations on the medial plateau and the peripheral area of the lateral plateau after four weeks of ACL transection and meniscectomy. Note: * indicates p < 0.05; ** p < 0.001. L = lateral plateau; M = medial plateau; bar = 20μm.
Fig 3.
Measurements of the CZC area in six selected locations on the tibial plateau of the PTOA and control knees.
A: The topographic distribution of CZC area is uneven across the tibial plateau in the control knees. The CZC areas at the peripheral and central regions on the lateral plateaus are larger than the corresponding locations on the medial plateau. In addition, there are significant differences in CZC area among several asymmetric locations between the lateral and medial plateaus. B: On the tibial plateaus of the PTOA joints, the number of significant differences in CZC area among different locations is reduced, as compared with the control tibial plateaus. C: Although the distribution pattern of CZC area in the PTOA joints is altered, the CZC areas sampled at each location of the PTOA tibial plateaus are unchanged when statistically compared with the corresponding locations in the control knees. Note: * indicates p < 0.05. L = lateral plateau; M = medial plateau.
Fig 4.
The tidemark roughness at the six selected locations on the tibial plateau of the PTOA and control knees.
The tidemark roughness in the control knees varies from area to area on the tibial plateau. In the PTOA knees, there are not regional differences in tidemark roughness. In addition, the generally reduced tidemark roughness in the PTOA knees is statistically significant at the central and medial areas of medial plateau, when compared with the controls. Note: * indicates p < 0.05. L = lateral plateau; M = medial plateau.
Fig 5.
Correlation between Mankin’s score and tidemark roughness.
In the PTOA knees, Mankin’s score and tidemark roughness are reversely correlated (p < 0.05).