(I-552) Comparison of Surrounding Soft Tissue Pressure Using 2 Different Lateral Retractors: Sweeping in Muscular Plane vs. Traditional Tubular Dilation.
Director Hoag Spine Center Irvine, California, United States
Introduction:
Introduction: Concerns of the lateral lumbar interbody fusion (LLIF) approach include the reports of postoperative incidence of thigh pain and paresthesias ranging from 14.3% to 20% and higher. The design and goal of the lateral retractor therefore, would be to minimize the disturbance to the psoas muscle fibers as well and the lumbosacral plexus . The sweeping muscle plane (SMP) lateral retractor has blades that begin in the plane parallel to the psoas muscle fibers, thus more anatomic and then open in a sweeping fashion to thereby reducing force on soft tissues. This will be compared to the traditional tubular dilation (TTD) retractor.
Methods:
Methods: Two senior spine surgeons performed the access and dilation on sixteen levels between L2-L5 on both sides of four whole-torso cadaver specimen. Each level was randomized to either Sweeping (n=8) or Traditional (n=8). A Codman ICP Express pressure transducer was inserted into the posterior aspect of the Psoas muscle 5mm from K-wire. Maximum pressure was measured as the magnitude of the highest pressure reached after a motion event, and equilibrium pressure was the magnitude at which it settled. Visual assessments were performed via digital photography, and dilation site assessed for deformation caused by excess pressure.
Results:
Results: Five different motion events: Dilation, Retractor Installation, Shim Installation, Blade Opening, and Blade Tilt were assessed for maximum measured pressure and equilibrium pressure. There was a significant difference between the SMP group and TTD group in equilibrium pressure for the Blade Opening event (3.63mmHg vs. 26.6mmHg) (p < 0.034), and the Blade Tilt event (3.50mmHg vs. 37.3mmHg) (p < 0.003). In addition, the different between SMP and TTD groups in maximum pressure for the Blade Opening event was also statistically significant (4.38mmHg vs. 43.8mmHg) (p < 0.013).
Conclusion :
Conclusion: There was a significant difference in the magnitude of maximum psoas pressure between the SMP group vs the TTD group for the blade opening action (p-value = 0.013). The difference in the magnitude of equilibrium pressure on the psoas between SMP group vs TTD group for Retractor installation and Blade opening actions were also significant (p-value = 0.056 and 0.013 respectively).
