Stability and Load Sharing Characteristics of a Posterior Dynamic Stabilization Device

Area of Science:

• Spinal surgery
• Biomechanics
• Orthopedic implants

Background:

• Lumbar interbody fusion is a common surgical procedure for spinal pathologies.
• Graft fusion may be hindered by inadequate mechanical loading.
• Evaluating mechanical stability and load sharing in anterior lumbar interbody fusion (ALIF) is crucial.

Purpose of the Study:

• Compare the mechanical stability of a posterior dynamic system versus titanium rods in an ALIF model.
• Assess anterior column loading sharing characteristics between the two systems.

Main Methods:

• Human cadaveric lumbar segments were utilized.
• Testing involved a pure moment flexibility protocol.
• Measurements included range of motion, interpedicular kinematics, and interbody graft loading.

Main Results:

• Both posterior dynamic systems and titanium rods provided significant spinal fixation.
• No significant differences in fixation were observed between the two device types.
• A decrease in graft loading was noted with titanium rods during flexion, but no significant differences were found between the posterior dynamic system and either the spacer alone or titanium rods.

Conclusions:

• The posterior dynamic system demonstrates fixation comparable to titanium rods.
• Cadaveric models with current techniques may lack the power to detect subtle differences in load sharing efficacy between spinal fixation devices.