Excursion of the Sciatic Nerve During Nerve Mobilization Exercises: An In Vivo Cross-sectional Study Using Dynamic Ultrasound Imaging.

STUDY
DESIGN: Controlled laboratory cross-sectional study using single-group, within-subject comparisons.
OBJECTIVES: To determine whether different types of neurodynamic techniques result in differences in longitudinal sciatic nerve excursion.
BACKGROUND: Large differences in nerve biomechanics have been demonstrated for different neurodynamic techniques for the upper limb (median nerve), but recent findings for the sciatic nerve have only revealed small differences in nerve excursion that may not be clinically meaningful.
METHODS: High-resolution ultrasound imaging was used to quantify longitudinal sciatic nerve movement in the thigh of 15 asymptomatic participants during 6 different mobilization techniques for the sciatic nerve involving the hip and knee. Healthy volunteers were selected to demonstrate normal nerve biomechanics and to eliminate potentially confounding variables associated with dysfunction. Repeated-measures analyses of variance were used to analyze the data.
RESULTS: The techniques resulted in markedly different amounts of nerve movement (P<.001). The tensioning technique was associated with the smallest excursion (mean ± SD, 3.2 ± 2.1 mm; P < or = .004). The sliding technique resulted in the largest excursion (mean ± SD, 17.0 ± 5.2 mm; P<.001), which was approximately 5 times larger than that resulting from the tensioning technique and, on average, twice as large as that resulting from individual hip or knee movements.
CONCLUSION: Consistent with current theories and findings for the median nerve, different neurodynamic exercises for the lower limb resulted in markedly different sciatic nerve excursions. Considering the continuity of the nervous system, the movement and position of adjacent joints have a large impact on nerve biomechanics.