Perilesional changes of focal osteochondral defects in an ovine model and their relevance to human osteochondral injuries

Abstract

Perilesional changes of chronic focal osteochondral defects were assessed in the knees of 23 sheep. An osteochondral defect was created in the main load-bearing region of the medial condyle of the knees in a controlled, standardised manner. The perilesional cartilage was evaluated macroscopically and biopsies were taken at the time of production of the defect (T0), during a second operation one month later (T1), and after killing animals at three (T3; n = 8), four (T4; n = 8), and seven (T7; n = 8) months. All the samples were histologically assessed by the International Cartilage Repair Society grading system and Mankin histological scores. Biopsies were taken from human patients (n = 10) with chronic articular cartilage lesions and compared with the ovine specimens. The ovine perilesional cartilage presented with macroscopic and histological signs of degeneration. At T1 the International Cartilage Repair Society 'Subchondral Bone' score decreased from a mean of 3.0 (SD 0) to a mean of 1.9 (SD 0.3) and the 'Matrix' score from a mean of 3.0 (SD 0) to a mean of 2.5 (SD 0.5). This progressed further at T3, with the International Cartilage Repair Society 'Surface' grading, the 'Matrix' grading, 'Cell Distribution' and 'Cell Viability' grading further decreasing and the Mankin score rising from a mean of 1.3 (SD 1.4) to a mean of 5.1 (SD 1.6). Human biopsies achieved Mankin grading of a mean of 4.2 (SD 1.6) and were comparable with the ovine histology at T1 and T3. The perilesional cartilage in the animal model became chronic at one month and its histological appearance may be considered comparable with that seen in human osteochondral defects after trauma.

A novel MSC‐seeded triphasic construct for the repair of osteochondral defects

“…This implant was compared to the clinically established OATS technique using a validated large animal model for degenerated critical-size cartilage defects. 22 In contrast to our first hypothesis, the OATS group did appear to have superior cartilage matrix morphology. However, histological analysis showed generally similar results between the osteochondral autograft and triphasic groups, as no significant differences were observed in the total sum of any of the 3 histological scores used for analysis.…”

“…To more accurately model the chronic cartilage damage seen in human subjects undergoing cartilage repair, use of a chronic injury model may be more appropriate. 22 Based on superior in vivo results for MSC-seeded constructs in comparison to chondrocyte-seeded implants 23 and due to the demonstrated osteogenic and chondrogenic potential of MSCs, 15,18,24−28 we developed a new MSC-based triphasic construct. The objective of this study was to compare the clinically established OATS technique with triphasic MSC-seeded implants for treatment of chronic osteochondral defects.…”

Isolation and Characterization of CD271⁺ Stem Cells Derived from Sheep Dermal Skin

“…The sheep represents an ideal large animal model for translational research based on MSCs, primarily to investigate orthopedic diseases, because its body weight, joint anatomy and MSC properties are comparable to humans [Guo et al, 2004;Lu et al, 2006;Mrugala et al, 2008;Hepp et al, 2009].…”

A low morbidity surgical approach to the sheep femoral trochlea

“…Several studies also used the ovine stifle joint to test implants [26] and as a model for osteoarthritis [27,28], cruciate ligament reconstruction [29,30], or meniscus repair [31]. However, the classical medial parapatellar arthrotomy includes surgical patellar luxation, unnecessarily increasing the risk for postoperative complications such as patellar luxation.…”