A surgical system has a device and an inertial measurement unit supported by the device body. Accordingly, the inertial measurement unit is configured to produce an inertial signal as a function of the movement of the device body. The system further has a controlling unit configured to determine the location of at least a portion of the movable device body as a function of the inertial signal. The controlling unit (e.g., in the sterile field) also uses a detected stationary artificial magnetic field at a prescribed location to determine information relating to the prescribed location. Importantly, the controlling unit also is configured to automatically zero-out the inertial measurement unit during use as a function of the information relating to the prescribed location. The controlling unit also has an output to transmit a position signal having positional information relating to the movable device body.

Disclosed herein are lock mechanisms configured for locking and unlocking rotation of a driver and a driven gear system in implantable distraction and compression systems, and implantable medical devices and implantable distraction and compression systems including such lock mechanisms. The lock mechanisms include a keeper that is configured to move from a locked position to an unlocked position in response to a rotation of the driver, wherein, in the locked position, the keeper is configured to resist rotation of the driven features and the driver under a load on the driven features, and in the unlocked position, permits rotation of the drive gear and the driver.

Systems and methods for joint replacement are provided. The systems and methods include a surgical orientation device and at least one orthopedic fixture. The surgical orientation device and orthopedic fixtures can be used to locate the orientation of an axis in the body, to adjust an orientation of a cutting plane or planes along a bony surface, to distract a joint, or to otherwise assist in an orthopedic procedure or procedures.