Hip Labral Reconstruction With a Synthetic Graft: Development and Preclinical Validation

Hip Osteoarthritis (OA) affects a significant component of the adult population, placing itself among the most important causes of disability and need for total hip replacement. Femoroacetabular impingement (FAI) is an anatomic alteration of the proximal femur and/or acetabulum leading to chondro-labral damage and playing a prominent role in OA pathogenesis. Thus, treating FAI is fundamental to relieve hip pain and further joint tissue deterioration. Labral reconstruction is considered the treatment of choice, in particular using tendon allografts or autografts which, however, have some limitations. Here, we investigated the possibility to create a synthetic graft for labral reconstruction to best restore the load bearing and ready to be used in the surgical room.

The graft was designed analyzing the anatomical structures from intact tissue samples. After a preliminary screening of different polymers, silicone was selected for its flexibility and elasticity to better adhere to the implantation site. We used an FDA-approved biocompatible silicone (VK100), and a mold casting was selected as a fabrication method. Cytocompatibility of VK100 was tested in vitro with an immortalized chondrocytes human cell line (C-28/I2). A cadaver lab was used to test the implantation procedure and to investigate the effects of the device transplantation on hip range of motion, translation, and resultant joint stability. To test the long-term strength of the reconstruction under cyclic loading, synthetic hemipelves were prepared for biomechanical testing and subjected to 10,000 cycles where deflections of up to 5 mm were imposed.

In vitro tests showed that up to 14 days of culture C-28/I2 cells were alive and adherent to VK100 surface with the formation of cell protrusions. As for cell cytotoxicity, a slight increase in LDH levels was observed at 14 days, probably due to the high confluence of adherent cells. We also demonstrated with the ex vivo procedure on cadaver that the device was suitable for arthroscopic implantation without damage or structural compromise during fixation to the acetabular bone. The range of motion and joint stability were preserved after implantation. Furthermore, the graft reconstruction successfully passed strenuous biomechanical cyclic loading. The force peak decreased by less than 10% during the test, indicating no detectable reduction of stiffness nor displacement/failure of the graft. No sign of damage was observed after test completion.

Overall, these results suggest that we have developed a functional synthetic graft that might be quickly transferred to clinical practice.