| 摘要 |
The present invention provides an improved orthopedic method and system for incremental adjustment of the bone segments on either side of a bone repair site. The apparatus includes a ratchet assembly which may be subcutaneously implanted, and an adjustment assembly which may be inserted percutaneously for releasable engagement with the adjustment assembly. The ratchet assembly includes a first piece having a tongue with ratcheting serrations, and a second piece having a cavity to receive the tongue and also including ratcheting pawls to engage the serrations. The serrations and the pawl cooperate to act as a uni-directional ratchet; depending on the geometry of the serrations, the ratchet assembly may operate as an incremental distractor or reducer. The adjustment assembly may be a simple threaded shaft which engages with a threaded bore on one of the pieces of the ratchet assembly; in this embodiment as the shaft is rotated, its end will provide a force to the other piece of the ratchet assembly. Alternatively, the adjustment assembly may be a plunger-type device having a sleeve portion which hooks onto one of the pieces of the ratchet assembly and a plunger portion which provides a force to the other piece of the ratchet assembly. The system advantageously allows the adjustment assembly to be removed from the patient when not in use, and provides a low-profile design for the adjustment assembly (reducer, distractor, etc.) which allows for convenient subcutaneous implantation. The adjustment assembly may be constructed in whole or part from bio-absorbable materials. |
