A biomechanical comparison between cortical bone trajectory fixation and pedicle screw fixation

Area of Science:

• Spine surgery
• Orthopedic biomechanics
• Spinal instrumentation

Background:

• Cortical bone trajectory (CBT) screws are an alternative fixation method in spinal surgery.
• Limited research exists on the biomechanical stability of functional spinal units using CBT fixation compared to pedicle screw (PS) fixation.

Purpose of the Study:

• To compare the intervertebral stability of the lumbar spine (L5-S1) after fixation with CBT screws versus PS.
• To evaluate the biomechanical performance of CBT fixation in terms of range of motion under bending and rotational loads.

Main Methods:

• Twenty lumbar spine specimens (L5-S1) were divided into two groups: CBT fixation (n=10) and PS fixation (n=10).
• Specimens underwent simulated bending and rotation tests using a six-axis material testing machine.
• Range of motion (ROM) and the rate of relative change in ROM were measured under load.

Main Results:

• No statistically significant differences were observed in the mean ROM between the CBT and PS groups during bending and rotation tests.
• The mean rate of relative change in ROM was also comparable between the CBT and PS fixation groups.

Conclusions:

• CBT screw fixation provides comparable intervertebral stability to traditional PS fixation in the lumbar spine.
• These findings suggest CBT screws are a viable alternative for achieving spinal stability.