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One hundred and one skeletally mature New Zealand White rabbits were used to study the long-term effects of a single injection of corticosteroid on the biomechanical, histological, and biochemical properties of ligament-healing. Two steroid doses were studied, as previously described. The injections were made into a fascial pocket immediately after transection of the ligament. The animals were killed forty-two and eighty-four days after the injury.In our previous investigation, in which we examined the early (inflammatory and proliferative) phases of ligament-healing, the specimens that had been injected with a dose of steroids equivalent to that given to humans demonstrated significantly inferior biomechanical properties and histological organization relative to controls that had not received an injection. In the current study, we examined the later (remodeling and maturation) phases of ligament-healing and found that the tensile strength (the ultimate stress) of the specimens that had been injected with the steroids returned to a value that was equal to that of the controls that had not received an injection; however, the peak load of the specimens that had been injected with steroids remained inferior to that of the controls. This was accompanied by a lag in the histological maturation.Delivery of a dose of steroids, equivalent to that given to humans, into an acutely injured ligament significantly impaired the healing process in the early phases of ligament-healing, compared with that in controls that were not given an injection. By eighty-four days, the tensile strength of the ligament returned to normal; however, the peak load and histological organization of the healing ligament did not normalize fully. This finding suggests that treatment of an injured ligament (a type-I collagenous structure) with corticosteroids is detrimental to the healing process. The effect of the steroids remains even eighty-four days after the injection. Intensive rehabilitation after injection of corticosteroids around injured type-I collagenous structures (ligaments and tendons) could potentially be harmful or lead to a reinjury.