Objective To investigate the role of β-catenin in pathogenesis and progression of knee primaryosteoarthritis (OA) by detecting the expression of β-catenin. Methods Between October 2010 and May 2011, 40 cartilagespecimens were collected from adult knee primary OA patients undergoing total knee arthroplasty and 10 cartilage specimensfrom adult patients suffering from amputation and femoral condylar fracture. All cartilage samples were taken out from femoralcondylar. The decalcified paraffin-embedded sections were prepared and stained with fast green-safranin O to observe thedegeneration of cartilage, then the modified Mankin scale was used to classify the degeneration. The expression of β-cateninwas detected by the immunohistochemistry staining and Western blot. Results According to the Mankin scale, 10 caseshad normal cartilage, 12 had mild degenerative cartilage, and 28 had moderate to severe degenerative cartilage. The histologicalobservation showed the mild degenerative cartilage characterized by fissures in the superficial zone of the articular cartilage,decreased chondrocytes, arrangement disorder, and duplicated tidemark; and the moderate to severe degenerative cartilagecharacterized by fissures in the deep zone of the articular cartilage, obviously decreased chondrocytes and cluster, and even fullthicknesscartilage defect. The β-catenin did not expressed in normal articular cartilage; but it expressed in the degenerativecartilage, and the expression was significantly higher in the moderate to severe degenerative cartilage than in mild degenerativecartilage (P lt; 0.05). Conclusion β-catenin plays a significant role in the pathogenesis and progression of knee primary OA,and the mechanism may be the activation of Wnt/β-catenin signaling pathway, which promotes transcri ption of inflammatorygenes and leads to the destruction of articular cartilage.
To investigate the pathologic characteristics of the articular cartilage and subchondral bone from osteoarthritic knees, and to compare the structural parameters of articular cartilage and subchondral bone between the medial and lateral tibial plateau, so as to determine the role of calcified zone and subchondral bone in the pathogenesis of osteoarthritis (OA). Methods The tibial plateaus were taken from 30 patients undergoing total knee arthroplasty between October 2009 and May 2011. The subjects included 11 males and 19 females with an average age of 65.1 years (range, 55-78years). The mean disease duration was 16.6 years (range, 10-25 years); the mean varus angle of the diseased knee was 9.3° (range, 1-23°). After gross observation, the cartilage-bone samples were taken out from the most weight-bearing regions in the internal areas of the medial and lateral plateaus. The decalcified paraffin-embedded sections were prepared and stained with HE and Safranin O/fast green for cartilage assessment (Mankin score), staging, and bone histomorphometry; the pathologic features of the cartilage and subchondral bone were also observed. The thickness of total articular cartilage (TAC), articular calcified cartilage (ACC), subchondral bone plate (SCP), and the trabecular bone volume (BV/TV) were measured by Image Pro Plus 6.0 imaging system, then the ratio of ACC/TAC was calculated. Results Macroscopic results showed that articular cartilage degeneration was more severe in the medial plateau than in the lateral plateau; Mankin score of the medial plateau (12.4 ± 1.1) was significantly higher than that of the lateral plateau (8.3 ± 1.6) (t=12.173, P=0.000). In the 60 samples, 14 samples were at stage I, characterisd by fissures within the superficial zone, dupl icated tidemark, and thickend subchondral bone; 19 samples were at stage II, characterisd by fissures extending into the deep zone, multiple subchondral bone resorption pits, and obviously thickend subchondral bone; and 27 samples were at stage III, characterisd by full-thickness cartilage defects, endochondral ossification, and eburnated subchondral bone. The bone histomorphometric study showed that TAC thickness of the medial plateau was significantly lower than that of the lateral plateau (P lt; 0.05); the ratios of ACC/TAC, BV/TV, and SCP thickness of the medial plateau were significantly higher than those of the lateral plateau (P lt; 0.05). However, there was no significantdifference in the ACC thickness between the medial and lateral plateaus (P gt; 0.05). Conclusion The calcified zone andsubchondral bone may play an important role in the initiation and progression of OA.