Does the application site of spinal manipulative therapy alter spinal tissues loading?

Area of Science:

• Biomechanics
• Spinal Manipulation Therapy
• Orthopedics

Background:

• Previous research indicates intervertebral discs (IVDs) bear maximal loads during spinal manipulation therapy (SMT).
• Understanding how SMT application site affects spinal tissue loading is crucial for optimizing treatment safety and efficacy.

Purpose of the Study:

• To investigate whether altering the SMT application site significantly modifies the loads experienced by spinal tissues.
• To compare the biomechanical effects of SMT applied to different anatomical locations on the lumbar spine.

Main Methods:

• A biomechanical study using a robotic serial dissection approach on thirteen porcine lumbar spine motion segments.
• Standardized 300 N SMT simulations were applied to six distinct cutaneous locations.
• Vertebral kinematics and forces on spinal structures were measured using optical tracking and a six-axis load cell, with sequential removal of spinal components.

Main Results:

• Significant differences (p<.05) in spinal structure loads were observed based on the SMT application site.
• SMT applied at the L3 vertebra induced vertebral movements and forces in the opposite direction compared to application at the L4 vertebra.
• SMT applied over the soft tissue between vertebrae significantly reduced spinal structure loads.

Conclusions:

• The site of SMT application critically influences spinal segment kinetics and the magnitude of loads on spinal tissues, even with constant applied force.
• Targeting soft tissue areas between vertebrae may offer a method to modulate and potentially reduce spinal loads during SMT.