Flexion Pain and Instability

Lumbar spinal flexion, or forward bending of the spinal column, is the most important motion of the lumbar spine. It has the largest range of motion^1,2 and is the most-exercised during activities of daily living.^3,4 The LimiFlex is the first spinal instrumentation system developed specifically to restore healthy kinematics in lumbar flexion.

Lumbar flexion extension chart

Bible et al. "Normal functional range of motion of the lumbar spine during 15 activities of daily living."
J Spinal Disord Tech. 2010, 23(2): 106-112.

Biomechanically, flexion increases loads in the anterior column of the spine, which can be associated with exacerbation of disc pain and degeneration.⁵ Furthermore, flexion instability is coupled with translational instability.

When a segment of the lumbar spine is in flexion, less of the facet’s articular surface is engaged, decreasing the resistance of the segment to shear forces. In addition, the portion of the facet that is engaged in flexion is less coronally oriented and therefore less capable of resisting segmental shear loads.^6,7

Facets limit sagittal translation

L4 vertebrae

Mated facets

L5 vertebrae

The facet joints are less engaged in flexion, and the parts of
the facets that are engaged provide less resistance to shear

Clinically, pain and instability on flexion affect over 400,000 patients worldwide annually.

Flexion has long been associated with clinical issues, including the following (click on link to see the corresponding sagittal plane image):

instability in flexion associated with degenerative spondylolisthesis
post-operative instability in flexion associated with surgical decompression
adjacent segment disease manifesting in flexion
pain on forward bending associated with degenerative disc disease

The LimiFlex Spinal Stabilization System addresses flexion instability associated with these pathologies.

Notes and References:

[1]

White AA, Panjabi MM. Clinical Biomechanics of the Spine, Second Edition. Lippincott Williams & Wilkins, 1990.

[2]

Benzel E. Biomechanics of Spine Stabilization. American Association of Neurological Surgeons (distributed by Thieme New York), 2001.

[3]

Morlock MM, Bonin V, Deuretzbacher G, Müller G, Honl M, Schneider E. "Determination of the in vivo loading of the lumbar spine with a new approach directly at the workplace – first results for nurses." Clin Biomech 2000, 15(8): 549-558.

[4]

Bible JE, Biswas D, Miller CP, Whang PG, Grauer JN. "Normal functional range of motion of the lumbar spine during 15 activities of daily living." J Spinal Disord Tech. 2010, 23(2): 106-112.

[5]

Wilke et al. "New in vivo measurements of pressures in the intervertebral disc in daily life," Spine (Phila Pa 1976). 1999 Apr 15;24(8):755-62.

[6]

Toyone T, Ozawa T, Kamikawa K, Watanabe A, Matsuki K, Yamashita T, Wada Y. "Facet Joint Orientation Difference Between Cephalad and Caudad Portions: A Possible Cause of Degenerative Spondylolisthesis." Spine 2009, 34(21): 2259-2262.

[7]

Grobler LJ, Robertson PA, Novotny JE, Pope MH. "Etiology of Spondylolisthesis: Assessment of the Role Played by Lumbar Facet Joint Morphology." Spine 1993, 18(1): 80-91.