Radiofrequency probe treatment for subfailure ligament injury: a biomechanical study of rabbit ACL

Abstract

Objective. Utilizing a rabbit anterior cruciate ligament model of ligamentous subfailure injury, biomechanical properties of injured ligament treated with radiofrequency energy were evaluated. It was hypothesized that an injured ligament treated with radiofrequency probe would demonstrate restoration of biomechanical properties lost through injury. Background. Radiofrequency probe, thermal treatment has been utilized in the clinical setting to address joint instability caused by ligamentous laxity from injury or repetitive microtrauma. The biomechanical effects of radiofrequency probe thermal treatment on injured ligamentous tissues have not been studied in the laboratory. Design. Three groups of specimens: Control, Sham, and Treatment, 10 each, were tested under identical conditions. Methods. Viscoelastic behavior was analyzed using a relaxation test (6% strain, up to 180 s) performed before injury, after injury, and after injury plus sham or injury plus radiofrequency probe treatment. Results. After injury the normalized forces in the relaxation test decreased by approximately 50%. The post-treatment relaxation test revealed significant ( P<0.01) restoration of the average relaxation force in the Treatment group to that of the Control group (0.79, SD 0.11 vs. 0.80, SD 0.10). Both of these groups were significantly different from the Sham group (0.44, SD 0.11). Additionally, stretch-to-failure test showed partial restoration of the toe region of the load–deformation curve by the radiofrequency treatment. Conclusions. The radiofrequency probe treatment is shown to be an effective mechanism for restoring initial ligament tensile stiffness and viscoelastic characteristics lost by the subfailure injury in vitro. Relevance This study employs a proven ligament subfailure injury model and examines the biomechanical consequences of radiofrequency probe thermal treatment, in vitro. These results support the theoretical basis of arthroscopic, electro-thermal capsule shift procedures for subfailure injuries. However, this study does not provide evidence that these improved biomechanical properties are sustained in vivo.