Persistent bone edema, anterior tibial pain and delay in bone neo-formation associated with Poly-L-lactic acid screws fixation of the anterior cruciate ligament graft

The anterior cruciate ligament has quickly become one of the most reconstructed ligamentous structures in the human body. Graft fixation options have evolved and expanded with time, the market now having numerous possibilities. It can be clearly seen that there is still plenty of debate regarding implant biocompatibility, resorption rates and osteoinductive capabilities. We aim to present a series of cases that presented with a delay in bone neo-formation, secondary bone edema surrounding the interference screw and persistent anterior tibial pain. Our lot was comprised of 5 men and 4 women with an average age of 27.7 (22-31) years old and an average time from the initial surgery of 17.77 (14-21) months. The MRI showed persistent edema located on the tibial end of the graft in 8 of our patients and no signs of implant resorption. The CT images showed little to no signs of bone neo-formation around the screw and graft. The KT tests showed significant differences (3mm or higher) in 2 patients and the average KOOS was 85 (79.2-88.7). The real question that needs to be raised is how do classic PLLA screws add up when compared to the new generation of implants that contain β-tricalcium phosphate or hydroxyapatite. As the surgical techniques will develop to less and less invasive, the implants must also evolve such as to allow faster graft integration and bone formation, resulting in smaller convalescence. An important part in research will be played by national ligamentoplasty registries that are still emerging in smaller countries.