Medtronic and San Diego-based NuVasive are accusing one another of patent infringement in a case involving products used in minimally invasive surgeries. Medtronic's Warsaw Orthopedic unit is accusing NuVasive of infringing three patents. Meanwhile, NuVasive maintains Medtronic Sofamor Danek USA is infringing its patent for a nerve monitoring system for lateral spinal surgery. News