Functional radiography (Cineradiography) of the Lumbar spine: Biomechanical implications for treatment

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A part of my review for a journal..................

Functional radiography or Cineradiography refers to radiography in the time course of the movement. Spine Cineradiography reveals many interesting aspects of stable (normal) & unstable (lysthetic) spine.

I. Normal spine flexion-extension kinesis

During flexion, initial lumbar motion starts stepwise from the upper level to the lower levels with phase lags. Angular velocity at the onset of motion increases as the level descended. On the contrary, during extension, initial motion started from the lower level (L5/S1) to the upper levels. There is no relation between velocity and spinal levels during backward flexion. Through out the F-E excursion there is a harmonious relation between the angular motion and translatory motion of the motion segment (10).

The motion profiles at L5/S1 were different between flexions & extension (11). In extension, motions in upper lumbar segments were small, and the L5-S1 segmental motion only contributed to the total lower lumbar motion (12).

What is phase lag?

The lumbar and lumbosacral segmental motions do not occur simultaneously but stepwise from the upper level with intersegmental motion lags during flexion. For example during lumbar spine flexion L4-L5 segmental motion is delayed from the L3-L4 motion by an average of 6 degrees and preceded the L5-S1 motion by an average of 8 degrees (12).

Normal spine & hip kinesis

Investigation of relation between the lumbar motion and hip joint motion reveal the lumbar motion preceded the hip flexion in forward bending and delayed from extension of the hip joints in backward bending.

II. Lysthetic spine flexion-extension kinesis

Lumbar kinesis study (10) of degenerative spondylolysthesis (L4 over L5) reveals

1. Forward Lysthesis less than 15% shows disharmonious angular motion & translatory motion in the lysthetic motion segment. The angular motion is large but translatory motion is moderately reduced.

2. Forward Lysthesis more than 15% also shows disharmonious angular motion & translatory motion in the lysthetic motion segment. The angular motion is moderately restricted but translatory motion is largely reduced.

3. While extending from flexion in patients with less than 15% slippage show large angulations and disordered motion pattern which is caused by segmental instability. While in patients with more than 15% slippage show decreased translation and disordered motion pattern during flexion is caused by restabilization.

References:

10. Takayanagi K et al; Spine. 2001 Sep 1;26(17):1858-65.
11. Harada M et al; Spine. 2000 Aug 1;25(15):1932-7.
12. Kanayama M et al; Spine. 1996 Jun 15;21(12):1416-22.

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