What determines whether I will have an operation from in front (anterior cervical discectomy and interbody fusion) or from behind (cervical laminectomy)?
Quite simply, if the disc or spur is pressing on the cord or nerve root from in front, then that is the preferred method of removal. In that way, the spinal cord or nerve root does not have to be retracted or even touched. The anterior route is preferred especially when there is just one level involved. If there are multiple levels, and/or if the pressure on the neural structures is from behind, then the preferred route is from behind.
