Development and Preclinical Validation of a Synthetic Graft for Hip Acetabular Labrum Reconstruction

Hip Osteoarthritis (HOA) affects a significant component of the adult population, being one of the most important causes of disability and need for total hip replacement (THR). Femoroacetabular impingement (FAI) plays a prominent role in the pathogenesis of HOA, especially in young adults. FAI is an anatomic alteration of the proximal femur and/or acetabulum, leading to chondro-labral damage. As it is fundamental to maintain joint hip stability and function, in the last decade the focus has moved to the importance of preserving the labrum, using arthroscopic surgery in FAI treatment. The aim of this study is to create and test a synthetic graft with an anatomical profile to restore the biomechanical function of the labrum, ready to be used in surgical room in a one-step procedure for a more effective and rapid surgical technique. Methods: The graft design was iteratively refined in conjunction with surgeons, based on the anatomy of the structures observed from intact tissue samples taken from THR patients. The graft was molded with an FDA-approved silicone (VK100, BONWRx, Lansing, USA). To test the implantability of the graft arthroscopically, and to optimize the procedure, a cadaver lab was first performed. To test the strength of the reconstruction under cyclic loading, n=4 composite hemipelves were “operated” and subjected to biomechanical testing (10'000 cycles, with up to 5.0mm imposed deflection). The VK100 cytocompatibility was tested up to 14 days in direct contact with an immortalized chondrocytes human cell line (C-28/I2). Results: During the procedure on cadaver, the final prototype showed significant ductility and suitability for arthroscopic implantation, without damage or structural compromise during fixation to the acetabular bone via high-strength suture threads. All the reconstructions on composite hemipelvises withstood the cyclic test with no sign of damage, despite the large cyclic deformation imposed. C-28/I2 cells were adherent to the VK100 surface with the formation of cell protrusions and filaments from day 1 to later timepoints. Concerning cell cytotoxicity, C-28/I2 cells showed the highest level of toxicity after 1 day from the seeding. After 7 days of culture, no sign of cell death was detected. At 14 days, a slightly increased value of cell stress was observed due to the high cell confluence. Conclusion: Our study represents a proof of concept to develop a bioartificial labrum as a new strategy to reduce the incidence of end-stage HOA and the need for THR in adolescents and young adults.