UC Davis

Ligaments play a crucial role in the musculoskeletal system in maintaining joint stability. Their primary function is to guide and restrain skeletal motion playing a vital role by forming a flexible skeletal joint between bones. When ligament injury occurs, a wound healing cascade begins with platelet plug formation and ends with tissue remodeling. Rat Medial Collateral Ligament (MCL) surgical and sub-maximal injury models were developed to examine footprint gait patterns, biochemical response, and histological tissue samples. Animals (n=150) were randomized to three treatments, Platelet Rich Fibrin (PRF) treatment, Meloxicam, a non-steroid anti-inflammatory drug (NSAID), and untreated animals. We examined injury and treatment effects up to day twenty-eight post-injury. Results show that untreated animals’ gait patterns recovered to normal function within seven days after injury, while anti-inflammatory drugs slowed functional recovery until day fourteen. The PRF-treated group showed the fastest functional recovery on day five. Biochemical evaluation with enzyme-linked immunoassay (ELISA) of the Vascular Endothelial Growth Factor (VEGF) showed a temporal effect with earlier peak VEGF concentration with PRF on day three compared to untreated animals peaking on day five and Meloxicam peaking on day seven. PRF reduces the time to functional recovery and correlates with early induction of VEGF. Even though NSAIDs manage the inflammatory response and pain, they retard functional recovery and VEGF induction. The histological assessment showed a temporal difference between day three and day twenty-eight regarding cellularity, collagen morphology and organization, and vascularity and set the stage to evaluate PRF and Meloxicam treatments on ligament healing. Establishing an animal model to study gross ligament injury and recovery sets the stage to study submaximal injury. Experiments have already designed an apparatus capable of producing submaximal injury. Initial studies have simulated mild ligamentous often experienced in different occupations requiring stooped posture work. Using a rodent model opens the opportunity to evaluate different approaches to improve ligament injury recovery and investigate various treatment methods.