Influence of 2 different dynamic stabilization systems on sagittal spinopelvic alignment

Area of Science:

• Spine surgery
• Orthopedics
• Biomechanical analysis

Background:

• Pedicle screw-based dynamic stabilization systems are widely used.
• Limited research exists on their impact on sagittal spinopelvic alignment and adjacent segment degeneration (ASD).

Purpose of the Study:

• To compare sagittal spinopelvic alignment changes between purely dynamic and hybrid pedicle screw stabilization systems.
• To evaluate the clinical implications of these alignment variations.

Main Methods:

• Retrospective analysis of lateral standing lumbar radiographs from 29 patients.
• Patients received either purely dynamic (Dynesys) or hybrid (FlexPLUS) stabilization systems.
• Measurements included L1-S1 lordosis, instrumented segment lordosis (ISL), cranial adjacent segment lordosis (CASL), highest instrumented segment lordosis (HISL), and spinopelvic parameters.

Main Results:

• Both systems showed a decrease in L1-S1 lordosis, with a greater significant loss in the purely dynamic group.
• The hybrid system demonstrated a significantly better preservation of instrumented segment lordosis (ISL) compared to the dynamic system.
• The hybrid system resulted in a significantly smaller increase in cranial adjacent segment lordosis (CASL) compared to the dynamic system.

Conclusions:

• Hybrid stabilization systems appear superior in preserving instrumented segment lordosis and minimizing compensatory changes in adjacent segments.
• This lordosis-preserving capacity may theoretically reduce the risk of adjacent segment degeneration (ASD).
• Further prospective studies are required to validate long-term outcomes and the relationship between lordosis preservation and ASD development.