Local Infiltrative Analgesia of Murine Femur Fractures In Vivo Does Not Inhibit Fracture Healing.

Abstract

The opioid epidemic in the United States has forced care providers to seek out alternatives to narcotic analgesics. Physicians involved in trauma care, including orthopaedic trauma surgeons, often have patients requiring significant amounts of these medications, especially in the perioperative period, given the acuity and severity of their injuries. Modalities such as local infiltration of fractures with anesthetic agents during operative treatment may provide some benefit to this population by decreasing postoperative pain and narcotic usage. However, prior data suggest that these agents are chondrotoxic, which may impede secondary fracture healing. The purpose of this study was to investigate the hypothesis that local anesthetics decrease secondary bone healing and callus formation in stabilized murine femur fractures through chondrocyte apoptosis. Male C57BL/6 mice underwent intramedullary stabilization and fracture of bilateral femurs followed by immediate infiltration of the fracture site with local anesthetic agents. Femurs were dissected at 10- and 20-days post-fracture and evaluated by muCT and histological analysis. No significant differences were seen in callus size or mineralization between controls and fractures treated with a local anesthetic. When the callus was analyzed histologically, local anesthetic agents appeared to increase cartilage density. Therefore, infiltration of local anesthetics during operative treatment of fracture as part of a multimodal approach to pain control does not appear to significantly affect callus formation in a preclinical model, although subclinical molecular effects may be present. Local infiltrative analgesia with local anesthetics may be used as an adjunct for perioperative pain control during femur fracture surgery without a significant effect on secondary bone healing.