Study to Prevent Cartilage Damage Following Acute Knee Injury.

Overview

Individuals who have had a severe knee injury have an increased risk of developing arthritis of the knee and at a much earlier age than would otherwise be expected. The swelling and inflammation that occur after injury are believed to be responsible for this cartilage damage. The cartilage (material that provides a cushion in the knee) is the primary protection from what is called degenerative arthritis or osteoarthritis. We hope to reduce this swelling and prevent the damage to cartilage that occurs after injury by injecting a medication that blocks one of the proteins responsible for inflammation and cartilage breakdown. This protein is called interleukin-1 and can be inhibited by an interleukin-1 receptor antagonist called anakinra. Anakinra will be injected directly into the injured knee and response to the injection will be measured by symptoms and analysis of cartilage breakdown in the knee fluid and blood.

Osteoarthritis is highly prevalent with significant impact on health care utilization and personal suffering. Injury predisposes to OA even after surgical correction (1, 2). Definitive therapy for established OA is lacking and current treatments are increasingly questioned with regard to long-term safety. Interleukin-1 is instrumental in OA pathogenesis (3-5). Recent studies by Chevalier demonstrated that intra-articular use of IL-1ra was safe in patients with established OA (6). We hope to show that IL-1ra will provide symptomatic benefit after knee injury as well as decreasing cartilage breakdown. The trial will consist of trial administering 150mg of Anakinra, or placebo, within 30 days of an acute knee injury that requires surgical repair. We hypothesize that higher IL-1 in synovial fluid after injury will predict greater symptomatic response to IL-1ra. Outcome measures will be functional and pain assessments at regular intervals before and after surgery (7, 8). Cartilage catabolism will be assessed with two primary measures. First we will assess degree of chondropathy via direct cartilage visualization and scoring at the time of arthroscopic repair (9). Secondly, the impact of IL-1ra on the inflammatory milieu will be determined through analysis of serum and synovial fluid cytokine levels and cartilage biomarkers at enrollment and again at the time of surgical repair. The impetus for this study is based on previous work done in animal models of OA, showing prevention of cartilage damage following surgically induced ACL injury (10-12). We believe that intra-articular delivery of anakinra within a short time following knee injury will improve patient function and pain reporting and will also prevent chondropathy that results from injury.