Effects of a delayed steroid injection on ligament healing using a rabbit medial collateral ligament model

Corticosteroids are known to inhibit collagen synthesis in vitro as well as having a deleterious effect on ligament healing when applied immediately following injury. An acute injection of betamethasone into a transected rabbit medial collateral ligament significantly impaired the biomechanical and histological properties compared to non-injected transected ligaments. Differences in mechanical, histological and biochemical properties were observed up to 3 months following injury and an acute steroid injection. The present study explored the effects of a corticosteroid (betamethasone) injection 7 days following the initial injury. Biomechanical and histomorphometric analyses were carried out to determine if the previously observed deleterious effects of a corticosteroid injection immediately following injury can be linked to an interference in the inflammatory phase of healing due to the presence of the corticosteroid.