The ventricular action potential has a long refractory period so that the mechanical response of the ventricle will be discrete; one coordinated mechanical response per electrâ¦ical activation sequence. Otherwise, with additional electrical stimuli, the mechanical responses would summate producing a prolonged contraction.
Microfracture Technique. Overview. Microfracture is a surgical technique that has been developed to treat chondral defects, which are damaged areas of articular cartilage of the knee. It is a common procedure used to treat patients with full thickness damage to the articular cartilage that goes all the way down to the bone.
During a microfracture, we clear off the loose pieces of cartilage and debris from the area where the cartilage is missing. Once we prepare the area we make many small holes or punctures in the bone (1-2 millimeters). Those holes communicate with the bone marrow where stem cells are located.