This is a single centre, non-blinded safety trial. Patients undergoing lumbar fusion will be treated using patient specific guides (PSG) or navigation. Patients requiring lumbar fusion will be treated using conventional surgical methods except when inserting pedicle screws, where half of the patients will be having screws inserted using PSGs. The conventional method of navigation and intraoperative imaging will be used in conjunction with PSGs, to confirm the safety of the guide trajectory. The primary outcome will be screw accuracy measured in degrees from planned trajectory and mm from the planned entry point.

Inclusion Criteria:

• Age 18 years or over
• Indication for lumbar spine surgery requiring pedicle screw instrumentation through a posterior approach with fusion.
• Recently has or requires a CT-scan of the spine
• No previous spine surgery on the level being used for patient specific guides
• Sufficient understanding of the English language or interpretation assistance available.

Exclusion Criteria:

• History of alcohol or drug abuse
• History of psychiatric disorders
• Previous spine surgery adjacent or at the level of the surgery
• Unable to read or comprehend the consent form/letter of information