Engineering large, anatomically shaped osteochondral constructs with robust interfacial shear properties.

Area of Science:

• Biomaterials Science
• Regenerative Medicine
• Orthopedic Surgery

Background:

• Large articular cartilage defects (>5 cm²) involving bone are common but poorly addressed by current therapies.
• Existing tissue-engineered treatments are limited to small defects, necessitating novel solutions for extensive lesions.

Purpose of the Study:

• To fabricate large, anatomically shaped, scaffold-free osteochondral constructs for repairing extensive cartilage defects.
• To evaluate the impact of neocartilage maturation timing on the interfacial properties of the osteochondral constructs.

Main Methods:

• Fabrication of osteochondral constructs using scaffold-free neocartilage (chondral phase) and porous hydroxyapatite (osseous phase).
• Constructs were shaped like ovine femoral condyles (31 × 14 mm) and assembled at different neocartilage maturation stages (day 4 - early, day 10 - late).
• Assessment of interfacial mechanical properties, including interdigitation and shear strength.

Main Results:

• Early osteochondral assembly (day 4) significantly enhanced interfacial properties compared to late assembly (day 10).
• Interfacial interdigitation depth increased by 244%, frequency by 438%, shear modulus by 243-fold, and ultimate shear strength by 4.9-fold with early assembly.
• The study successfully generated large, anatomically shaped osteochondral constructs with robust interfacial mechanical properties.

Conclusions:

• Early assembly of scaffold-free neocartilage with a hydroxyapatite substrate yields osteochondral constructs with superior interfacial integration and mechanical strength.
• These findings support the development of off-the-shelf, bioprosthetic implants for repairing large, full-condyle cartilage defects.
• The developed technique offers a promising approach for treating extensive osteochondral lesions, potentially restoring native joint function.