[The development of a bilateral groove lengthener]

A new series of bilateral groove external fixator are introduced in the article, which are mainly used to treat limb crispation. These apparatuses are composed of the groove frame threaded rod, hooked bolts, nuts and pins. They can be adjusted in several directions to correct the axis of limb in limb lengthening. The pins can be fixed on the anterior and posterior sides of the frame, with a stable angle structure. The devices are light and practical, with multiple functions, low price, simple and convenient operation. It can apply to all kinds of hospitals.