Distraction device for moving apart two bone sections

Abstract

The invention concerns a distraction device for moving apart two bone sections, in particular for extending bones or bridging a gap in a bone, the device comprising an intramedullary nail (1) which can be introduced into the medullary space of a bone and comprises two parts (2, 3) which can be moved axially and can each be secured to one of the two bone sections. The distraction device further comprises a drive unit (4) that drives a drive shaft (16), and a device for converting the rotational movement of the drive shaft (16) into a relative axial movement of the two parts (2, 3) of the intramedullary nail (1). In order to increase operational reliability and reduce the overall size of the device while retaining the high degree of efficiency, the drive shaft (16) drives planetary rollers (19) which are held on orbits on which they engage by means of drive grooves (21) provided on their outer periphery in corresponding drive grooves (8) in a hollow body (7) surrounding the planetary rollers (19), at least the drive grooves (8) of the hollow body (7) or of the planetary rollers (19) being designed as threaded grooves in order to displace the hollow body (7) axially relative to the drive shaft (16) when the latter is rotated.

Dependencies are inferred from the claim text.