This instrumentation comprises valves (2) for shifting aside tissues and vessels, pins for fixing each valve (2) to the spine, each valve (2) comprising for this purpose sleeves (6) in which the pin (5) is slidable; the instrumentation further comprises, for each valve (2), an articulated device (7)...http://www.google.com/patents/US6083154?utm_source=gb-gplus-sharePatent US6083154 - Surgical instrumentation and method for retracting and shifting tissues
