The Morphological, Clinical and Radiological Outputs of the Preclinical Study After Treatment of the Osteochondral Lesions in the Porcine Knee Model Using Implantation of Scaffold Based on the of Calcium Phosphate Biocement

The symptomatic full-thickness cartilage lesions or cartilage degeneration leads to the destruction of the normal chondral architecture and bone structure in affected area, causes the osteoarthritis, and general damage to the health. Knee joints are most frequently affected by this condition. The permanent damage of the articular cartilage and subchondral bone has motivated many scientists and clinicians to explore new methods of regeneration of osteochondral defects, such as novel materials. We studied the potential of the biocement based on calcium phosphate consisting of a mixture of four amino acids (glycine, proline, hydroxyproline and lysine) in the regenerating process of the artificially created osteochondral defect on the porcine medial femoral condyle in the stifle joint. The mass ratio of the amino acids in biocement CAL was 4:2:2:1. The Ca/P ratio in cement was 1.67 which correspond with ratio in hydroxyapatite. We compared the results with spontaneous healing of an artificially created cyst with that of the healthy tissue. The animal group treated with biocement paste CAL presented completely filled osteochondral defects. The results were confirmed by histological and radiological assessments, which have shown regenerated chondral and bone tissue in the examined knee joints. Macroscopic evaluation showed that neocartilage was well integrated with the adjacent native cartilage in animal group with biocement CAL, compared with healing of the artificial cyst, where treated cartilage surfaces were visibly lower than the surrounding native cartilage surface and a border between native and restored tissue was apparent. The qualitative assessment of the implant histology specimens showed full regeneration of the hyaline cartilage and subchondral bone in animals with biocement CAL. The artificial cyst group showed remarkable fibrillation. The detailed MRI analysis of cross-section of osteochondral defect confirmed the complete cartilage and subchondral bone healing where the thickness of the regenerated cartilage was 1.5 mm. The MRI imaging of defects in the artificial cyst group showed incomplete healing, neo cartilage tissue reduced up to 50%.

Human tissue culture of osteochondral defect: An advanced in vitro model

The optimization of advanced in vitro models is essential for the development of alternative methods. The in vitro study of osteochondral regeneration still has numerous limitations and wide scope for exploration.

In Vivo Study of Osteochondral Defect Regeneration Using Innovative Composite Calcium Phosphate Biocement in a Sheep Model

This study aimed to clarify the therapeutic effect and regenerative potential of the novel, amino acids-enriched acellular biocement (CAL) based on calcium phosphate on osteochondral defects in sheep. Eighteen sheep were divided into three groups, the treated group (osteochondral defects filled with a CAL biomaterial), the treated group with a biocement without amino acids (C cement), and the untreated group (spontaneous healing). Cartilages of all three groups were compared with natural cartilage (negative control). After six months, sheep were evaluated by gross appearance, histological staining, immunohistochemical staining, histological scores, X-ray, micro-CT, and MRI. Treatment of osteochondral defects by CAL resulted in efficient articular cartilage regeneration, with a predominant structural and histological characteristic of hyaline cartilage, contrary to fibrocartilage, fibrous tissue or disordered mixed tissue on untreated defect (p < 0.001, modified O’Driscoll score). MRI results of treated defects showed well-integrated and regenerated cartilage with similar signal intensity, regularity of the articular surface, and cartilage thickness with respect to adjacent native cartilage. We have demonstrated that the use of new biocement represents an effective solution for the successful treatment of osteochondral defects in a sheep animal model, can induce an endogenous regeneration of cartilage in situ, and provides several benefits for the design of future therapies supporting osteochondral defect healing.

The Effect of Talus Osteochondral Defects of Different Area Size on Ankle Joint Stability: A Finite Element Analysis

(1) Background: Osteochondral lesion of the talus (OLT) is one of the common ankle injuries, which will lead to biomechanical changes in the ankle joint and ultimately affect the ankle function. The finite element analysis (FEA) was used to clarify the effect of talus osteochondral defects in different depths on the stability of the ankle joint. However, there is no clear research about the area of talus osteochondral defects that should be intervened in time. In this research, FEA is used to simulate the effect of different areas size of talus osteochondral defect on the stress and stability of ankle joint under a certain depth defect.; (2) Methods: The different area size (Normal, 2 mm* 2 mm, 4 mm* 4 mm, 6 mm* 6 mm, 8 mm* 8 mm, 10 mm* 10 mm, 12 mm* 12 mm) of osteochondral defects three-dimensional finite element model was established to simulate and calculate joint stress and displacement of the articular surface of the distal tibia and the proximal talus while the ankle joint was in the push-off phase, midstance phase and heel-strike phase; (3) Results: When OLT occurred, the contact pressure of articular surface, the equivalent stress of the proximal talus, tibial cartilage and talus cartilage did not change significantly with the increase of osteochondral defect area size in heel-strike phase below 6 mm * 6 mm, it increased gradually from 6 mm * 6 mm in midstance phase and push-off phase, and reached the maximum when the defect area size is 12 mm * 12 mm. The talus displacement also has the same tendency.; (4) Conclusions: The effect of cartilage area size defects of the talus on the biomechanics of the ankle is obvious especially in the midstance phase and push-off phase. When the defect size reaches 6 mm * 6 mm, the most obvious change in the stability of the ankle joint occurs, and the effect does not increase linearly with the increase in the depth of the defect.