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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.

Kuroki H, Nakagawa Y, Mori K, Ohba M, Suzuki T, Mizuno Y, Ando K, Takenaka M, Ikeuchi K, Nakamura T - Arthritis Res. Ther. (2004)

Bottom Line: 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 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).

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Orthopaedic Surgery, School of Health Sciences, Faculty of Medicine, Kyoto University, Kyoto, Japan. kuro@hs.med.kyoto-u.ac.jp

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 cartilage-like 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.

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Macroscopic findings. A full-thickness osteochondral plug of 5 mm in diameter and 7 mm in depth was harvested from the patellar groove. Articular cartilage around the hole was shaved in a 7 × 7 mm square until bleeding from the subchondral bone was observed. The harvested plug was then returned precisely to its original site. (a) At day 0, the plug was intact and the margin around the plug and the shaved square was clearly recognizable. (b) At 2 weeks postoperatively, the margin around the square could be clearly detected. Although the articular surface of the plug was smooth and regular, the plug had subsided a little. (c) The margin around the plug and the shaved square could be easily detected at 4 weeks. (d) At 8 weeks postoperatively the margin was a little faint but could still be detected. At 4 (panel c) and 8 weeks (panel d), the site around and over the plug was filled with newly formed reparative tissue. Although the surface of the plug and the defect looked irregular, the plug was glossy. (e) The margin around the plug and the shaved square was a little faint but could still be detected at 12 weeks. (f) At 24 weeks postoperatively, however, the margin was very faint. The plug survived well and osteoarthritic changes such as osteophyte formation were not observed at 12 and 24 weeks postoperatively (panels e and f). The surface of the plug cartilage was as smooth as that of the adjacent intact cartilage.
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Figure 3: Macroscopic findings. A full-thickness osteochondral plug of 5 mm in diameter and 7 mm in depth was harvested from the patellar groove. Articular cartilage around the hole was shaved in a 7 × 7 mm square until bleeding from the subchondral bone was observed. The harvested plug was then returned precisely to its original site. (a) At day 0, the plug was intact and the margin around the plug and the shaved square was clearly recognizable. (b) At 2 weeks postoperatively, the margin around the square could be clearly detected. Although the articular surface of the plug was smooth and regular, the plug had subsided a little. (c) The margin around the plug and the shaved square could be easily detected at 4 weeks. (d) At 8 weeks postoperatively the margin was a little faint but could still be detected. At 4 (panel c) and 8 weeks (panel d), the site around and over the plug was filled with newly formed reparative tissue. Although the surface of the plug and the defect looked irregular, the plug was glossy. (e) The margin around the plug and the shaved square was a little faint but could still be detected at 12 weeks. (f) At 24 weeks postoperatively, however, the margin was very faint. The plug survived well and osteoarthritic changes such as osteophyte formation were not observed at 12 and 24 weeks postoperatively (panels e and f). The surface of the plug cartilage was as smooth as that of the adjacent intact cartilage.

Mentions: At day 0 (Fig. 3a) the plug was intact and the margins around the plug and the shaved square were clearly apparent. At 2 weeks postoperatively (Fig. 3b) the margin around the square could be clearly detected. Although the articular surface of the plug was smooth and regular, the plug had subsided a little.


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.

Kuroki H, Nakagawa Y, Mori K, Ohba M, Suzuki T, Mizuno Y, Ando K, Takenaka M, Ikeuchi K, Nakamura T - Arthritis Res. Ther. (2004)

Macroscopic findings. A full-thickness osteochondral plug of 5 mm in diameter and 7 mm in depth was harvested from the patellar groove. Articular cartilage around the hole was shaved in a 7 × 7 mm square until bleeding from the subchondral bone was observed. The harvested plug was then returned precisely to its original site. (a) At day 0, the plug was intact and the margin around the plug and the shaved square was clearly recognizable. (b) At 2 weeks postoperatively, the margin around the square could be clearly detected. Although the articular surface of the plug was smooth and regular, the plug had subsided a little. (c) The margin around the plug and the shaved square could be easily detected at 4 weeks. (d) At 8 weeks postoperatively the margin was a little faint but could still be detected. At 4 (panel c) and 8 weeks (panel d), the site around and over the plug was filled with newly formed reparative tissue. Although the surface of the plug and the defect looked irregular, the plug was glossy. (e) The margin around the plug and the shaved square was a little faint but could still be detected at 12 weeks. (f) At 24 weeks postoperatively, however, the margin was very faint. The plug survived well and osteoarthritic changes such as osteophyte formation were not observed at 12 and 24 weeks postoperatively (panels e and f). The surface of the plug cartilage was as smooth as that of the adjacent intact cartilage.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC1064862&req=5

Figure 3: Macroscopic findings. A full-thickness osteochondral plug of 5 mm in diameter and 7 mm in depth was harvested from the patellar groove. Articular cartilage around the hole was shaved in a 7 × 7 mm square until bleeding from the subchondral bone was observed. The harvested plug was then returned precisely to its original site. (a) At day 0, the plug was intact and the margin around the plug and the shaved square was clearly recognizable. (b) At 2 weeks postoperatively, the margin around the square could be clearly detected. Although the articular surface of the plug was smooth and regular, the plug had subsided a little. (c) The margin around the plug and the shaved square could be easily detected at 4 weeks. (d) At 8 weeks postoperatively the margin was a little faint but could still be detected. At 4 (panel c) and 8 weeks (panel d), the site around and over the plug was filled with newly formed reparative tissue. Although the surface of the plug and the defect looked irregular, the plug was glossy. (e) The margin around the plug and the shaved square was a little faint but could still be detected at 12 weeks. (f) At 24 weeks postoperatively, however, the margin was very faint. The plug survived well and osteoarthritic changes such as osteophyte formation were not observed at 12 and 24 weeks postoperatively (panels e and f). The surface of the plug cartilage was as smooth as that of the adjacent intact cartilage.
Mentions: At day 0 (Fig. 3a) the plug was intact and the margins around the plug and the shaved square were clearly apparent. At 2 weeks postoperatively (Fig. 3b) the margin around the square could be clearly detected. Although the articular surface of the plug was smooth and regular, the plug had subsided a little.

Bottom Line: 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 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).

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Orthopaedic Surgery, School of Health Sciences, Faculty of Medicine, Kyoto University, Kyoto, Japan. kuro@hs.med.kyoto-u.ac.jp

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 cartilage-like 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.

Show MeSH
Related in: MedlinePlus