ABSTRACT
The medial collateral ligament (MCL) is a major contributor to knee joint stability and is the most common ligament involved in knee injuries. When conservative management for high-grade MCL injuries fails, operative treatment is indicated. Various reconstruction techniques are described in the literature. The following report describes a reconstruction technique based on the modified Bosworth. We present a step-by-step technique for using autograft semitendinosus tendon as a double limb to reconstruct the MCL and if necessary, the posterior oblique ligament. The technique is versatile with respect to a spectrum of MCL injury patterns, isometric, incorporates techniques that are common to other knee reconstructions, and uses readily available autograft. It has been used extensively by the senior authors as an adjunct/augmentation to the repair of acute MCL injuries as well as in the reconstruction of chronic MCL laxity. The technique restores stability to rotation and valgus stress while maintaining the distal insertion of the semitendinosus intact.
ABSTRACT
Regenerative therapies for cartilage defects have been greatly advanced by progress in both the stem cell biology and tissue engineering fields. Despite notable successes, significant barriers remain including shortage of autologous cell sources and generation of a stable chondrocyte phenotype using progenitor cells. Increasing demands for the treatment of degenerative diseases, such as osteoarthritis and rheumatoid arthritis, highlight the importance of epigenetic remodeling in cartilage regeneration. Epigenetic regulatory mechanisms, such as microRNAs, DNA methylation, and histone modifications, have been intensively studied due to their direct regulatory role on gene expression. However, a thorough understanding of the environmental factors that initiate these epigenetic events may provide greater insight into the prevention of degenerative diseases and improve the efficacy of treatments. In other words, if we could identify a specific factor from the environment and its downstream signaling events, then we could stop or retard degradation and enhance cartilage regeneration. A more operational definition of epigenetic remodeling has recently been proposed by categorizing the signals during the epigenetic process into epigenators, initiators, and maintainers. This review seeks to compile and reorganize the existing literature pertaining to epigenetic remodeling events placing emphasis on perceiving the landscape of epigenetic mechanisms during cartilage regeneration with the new operational definition, especially from the environmental factors' point of view. Progress in understanding epigenetic regulatory mechanisms could benefit cartilage regeneration and engineering on a larger scale and provide more promising therapeutic applications.
