Bone density comparison between the normal pedicle trajectory, cortical bone trajectory, and modified cortical bone...

Area of Science:

• Spine surgery
• Orthopedic biomechanics
• Radiology

Background:

• Cortical bone trajectory (CBT) offers improved screw fixation due to enhanced bone contact.
• However, CBT may limit screw size and fixation depth within the vertebral body.
• Original pedicle trajectory (OPT) is a traditional method with known limitations.

Purpose of the Study:

• To compare bone density using computed tomography Hounsfield units (CTHU) among original pedicle trajectory (OPT), cortical bone trajectory (CBT), and modified cortical bone trajectory (MCBT).

Main Methods:

• A cross-sectional study analyzed computed tomography scans of 1,000 lumbar vertebrae (L1-L5) from 200 patients.
• Bone density (CTHU) was measured at four points (posterior cortex, mid-pedicle, midbody, anterior cortex) for OPT, CBT, and MCBT planes.
• Statistical analysis compared CTHU values across trajectories and evaluated age-related bone density decline.

Main Results:

• Mean CTHU values were significantly different: OPT (354.2±70 HU), CBT (529.9±75 HU), and MCBT (457.3±90 HU) (p <0.01).
• MCBT's posterior cortex CTHU was 65.6% higher than OPT and 14.9% lower than CBT.
• Bone density decline with age was less pronounced in MCBT and CBT compared to OPT.

Conclusions:

• Modified cortical bone trajectory (MCBT) demonstrates significantly higher bone density than original pedicle trajectory (OPT).
• MCBT achieves posterior cortical bone density comparable to CBT.
• MCBT presents a promising alternative trajectory for lumbar spine fixation.