• Benjamin S Boyd, Kimberly S Topp, and Michel W Coppieters.
• Department of Physical Therapy, Samuel Merritt University, 450 30th Street, Suite 3724, Oakland, CA 94609, USA. bboyd1@samuelmerritt.edu
• J Orthop Sports Phys Ther. 2013 Jun 1; 43 (6): 398-403.

Study DesignLaboratory study, repeated-measures design.ObjectivesTo quantify differences in sciatic and tibial nerve biomechanics (strain and excursion) during common variations of the straight leg raise (SLR) test.BackgroundHip flexion and ankle dorsiflexion are the primary movement components of the SLR. It has been suggested that the nervous system is loaded differently when ankle dorsiflexion is added before or after hip flexion. There are, however, no data to either support or refute this suggestion.MethodsStrain and excursion in the sciatic and tibial nerve were measured in the hip, knee, and ankle regions during 2 movement sequences for the SLR test in 10 embalmed cadavers. The proximal-to-distal sequence consisted of hip flexion followed by ankle dorsiflexion; the distal-to-proximal sequence consisted of ankle dorsiflexion followed by hip flexion.ResultsIn the SLR end position, strain and excursion were comparable for both sequences for the sciatic and tibial nerve at the knee (P>.24). Strain in the tibial nerve at the ankle was greater with the proximal-to-distal sequence (P = .008), but the actual difference was small (0.8%). The pattern of strain increase and nerve excursion varied between sequences (P≤.009), with nerve strain increasing earlier and being maintained longer in regions closest to the joint that was moved first in the movement sequence.ConclusionVarying the movement sequence does not substantially impact excursion and strain in the end position of the SLR. Therefore, if neurodynamic test sequencing is useful in the differential diagnosis of neuropathies, it is not likely due to differences in strain in the end position of testing.

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