Influence of local steroid injections on traumatized tendon properties. A biomechanical and histological study.

We investigated the effects of peritendon injections of hydrocortisone acetate on the separation force required to completely avulse a posttraumatized Achilles tendon of the adult male rat. One hundred thirty-five rats were randomly assigned to 3 groups and subsequently traumatized, treated, and sacrificed. One group was used to examine the effect of trauma; the second to examine effects of trauma and injections of hydrocortisone acetate on the tension to failure strength of tendons; the third group was the control group. Injected animals received one, three, or five injections of 0.10 cc (125 mg/ml) hydrocortisone acetate and were sacrificed 3, 6, or 9 weeks following initial injection. Experimental animals (anesthetized) were traumatized by dropping a weight onto the Achilles tendon. The tendon was tested in tension to failure employing a soft tissue linear disseminator. Histologic analysis using light microscopy was performed. We concluded that hydrocortisone acetate has no deleterious effect on the rat Achilles tendon as measured biomechanically or histologically.