INTRAMEDULLARY SKELETAL DISTRACTOR AND METHOD

摘要

A device (10) for effecting progressive elongation of a sectioned bone having no extracutaneous elements, and a method for using the device (10), are presented. The device (10), which includes a pair of telescopically engaged cylindrical members (20, 30), is inserted into the medullary space of the bone, and one cylindrical member (20, 30) is affixed to each section of bone. Under the normal torsions experienced by the affected limb, a clutch mechanism (60, 70) is provided that causes the cylindrical members (20, 30) to be forced apart, separating the sections of bone, at which site new bone growth is stimulated. Rotations as small as 1 degree are sufficient to activate elongation. In order to limit excessive rotational displacement, a key ring mechanism (95) is provided that limits rotation to that which is anatomically tolerated yet provides sufficient lengthening, typically between 3 and 5 degrees. In order that excessive separation of the cylindrical members do not occur, an indicator mechanism (50) is further provided that prevents elongation beyond a predetermined amount per unit time. The indicator mechanism (50) can be overcome by forcible external manipulation so that a new cycle of elongation may begin.