Acoustic stiffness and change in plug cartilage over time after autologous osteochondral grafting: correlation between ultrasound signal intensity and histological score in a rabbit model

Abstract

We investigated quantitative changes over time in ultrasound signal intensity (an index of stiffness), signal duration (an index of surface irregularity), and interval between signals (an index of thickness) of plug cartilage in an animal model of autologous osteochondral grafting. A full-thickness osteochondral plug was surgically removed and replaced in male Japanese white rabbits (n = 22). Specimens obtained at day 0 and weeks 2, 4, 8, 12 and 24 postoperatively were assessed using an ultrasound system and by macroscopic and histological evaluation (modified Mankin's score). Histology revealed that the plug sank until 2 weeks postoperatively, and that newly formed cartilagelike tissue covered the plug, but at 24 weeks the tissue detached. The plug itself survived well throughout the period of observation. Although the signal intensity at the plug site was same as that in the sham operated contralateral knee at day 0, from 2 to 24 weeks postoperatively it was less than that in the sham knee. At 8 weeks, this difference was significant (P < 0.05). Modified Mankin's score revealed early degenerative changes at the site, but macroscopic examination did not. Signal intensity correlated significantly with score (both at day 0 and at the five postoperative time points [P < 0.05, r = -0.91] and as a whole [P < 0.05, r = -0.36]). Signal intensity also significantly correlated with the individual subscores for 'cartilage structure' (P < 0.05, r = -0.32) and 'cartilage cells' (P < 0.05, r = -0.30) from the modified Mankin's score, but not significantly with subscores for 'staining' and 'tidemark'. Signal duration correlated significantly with total score (as a whole [P < 0.05, r = 0.34]), but not significantly with the score for cartilage structure (P = 0.0557, r = 0.29). The interval between signals reflected well the actual thickness of the plug site. The significant relationships between ultrasound signal intensity and scores suggest that early degenerative changes in plug cartilage and cartilage-like tissue, especially in the superficial layer, are detectable by high-frequency ultrasound assessment.

Bach1 deficiency reduces severity of osteoarthritis through upregulation of heme oxygenase-1

“…In this study, we applied multiple separate scoring systems for articular cartilage, meniscus, synovitis, osteophyte formation and subchondral bone thickening. Osteoarthritic damage of articular cartilage was scored using a modified Mankin system [ 18 , 19 ]. Meniscus degradation was evaluated using a scoring system [ 20 ] which included the following 6 criteria, meniscus integrity (0 = smooth surface, 1 = irregularity of superficial layer or slight fibrillation, 2 = moderate fibrillation, 3 = severe fraying, tear or disruption), collagen structure (0 = normal, 1 = slight disturbance, 2 = moderate disturbance, 3 = severe disturbance or mucoid substances), cellular abnormalities (0 = normal, 1 = hypercellularity, 2 = cloning tendency, 3 = hypocellularity), stainability of safranin O staining (0 = normal, 1 = slight reduction, 2 = moderate reduction, 3 = severe reduction), calcification and cyst formation (0 = normal, 1 = slight, 2 = moderate, 3 = severe).…”

Preliminary histopathological study of intra-articular injection of a novel highly cross-linked hyaluronic acid in a rabbit model of knee osteoarthritis

“…Safranin-O staining was used for the evaluation of degenerative cartilage lesions. Histological samples were graded using a modified Mankin’s score (0–2: normal; 3–5: OA grade I; 6–7: OA grade II; 8–10: OA grade III; 11–14: OA grade IV) to evaluate structure, fissures, clefts, cells, vascularity and saturation of articular cartilage (Kuroki et al 2004). The maximum score can be achieved when facing heavily disintegrated and degenerated cartilage.…”

Comparison of cartilage histopathology assessment systems on human knee joints at all stages of osteoarthritis development

“…These systems assess similar parameters as the original MANKIN system, but parameters such as Safranin O staining intensity or cellularity for example are either scored in a different fashion, or an overall score is normally applied instead of separate subscores [3–8]. Since the MANKIN system was based on specimens with advanced OA, it may have limitations for mild and moderate OA [9].…”