Tuesday, August 4, 2009

Spine Asymmetry & LBA (specific focus on lumbo-pelvic spine)

Introduction:

Subtle pelvic asymmetry (exhibited as either lateral pelvic tilt or iliac rotational asymmetry), which is common among normal individuals, has not been convincingly linked to abnormalities in back. Given the difficulty in diagnosing most LBA, a classification using pelvic asymmetry and patterns of movement are helpful in establishing a rational treatment plan (2).

I. Impact of pelvic asymmetry in work-stations:
Structural and functional asymmetries are factors that may be considered in the seating design and work environment (1). A study consisting of 59 subjects revealed that significant:
(1) Correlations between pelvic asymmetry and asymmetric trunk motion performed in sitting.
(2) Differences between the LBP and control groups in patterns of trunk motion performed in a sitting posture.
(3) Differences between kinematics of motions performed in sitting versus standing postures.

This study concluded that in LBA cases pelvic asymmetry and altered trunk motion in sitting position exists specifically of lateral flexion and axial rotation. Movement asymmetry, rather than range of motion, becomes a better indicator of disturbed spine function. People with LBA have a distinct compensatory mechanism, secondary to pelvic asymmetry, which puts the lumbar spine under higher stress (1).

II. Differences in FB (forward bending) in LBA cases & girdle pain patients:
BP and PGP patients show specific, consistent, and distinct motion patterns. One study (3) tried to identify differences in forward bending in 2 subcategories of back pain patients in females. Patients either with low back pain (LBP) or pelvic girdle pain (PGP) ware compared with motion characteristics of healthy subjects. Chronic LBP can be distinguished from PGP using specific evidence-based diagnostic tests.

Forward bending was studied with specific reference of trunk motion, pelvic tilt, and lumbar lordosis. This study has following findings:
1. During erect stance in the PGP group, the pelvis is significantly tilted backwards.
2. At maximally forward bending, the ROM of the trunk is limited in all patient groups, but only the PGP group has significantly limited hip motion.
3. During the initial part of forward bending, lumbar motion is increased in PGP patients and decreased in LBP patients.
4. In the final part of forward bending contribution of the lumbar spine is increased in both patient groups.

The authors of this study concluded that these motion patterns are functional compensation strategies, following altered neuromuscular coordination.

III. Pelvic asymmetry & Lumbar spine:
There are differences in patterns of lumbar movement between asymptomatic subjects and patients with LBA. Subtle anatomic abnormality in the pelvis is associated with altered mechanics in the lumbar spine. Further, asymmetry of lumbar movement is suggested to be a better indicator of functional deficit than the absolute range of movement in LBA (1).
LBA patients exhibit different pattern of coupled rotation during lateral flexion. Asymmetry in lumbar lateral flexion was highly related to two types of pelvic asymmetry: lateral pelvic tilt (LPT) and iliac rotation asymmetry (IRA). Asymmetry in lumbar axial rotation is highly related to IRA but weakly related to LPT (2).

IV. Lumbar spine asymmetry & LBA
Leach & colleagues reported thoracolumbar asymmetry, contralateral responsivity (increased myoelectric activity opposite the side of leg pain), loss of flexion/relaxation (F/R) at L3 and right/left asymmetry (R-L/A) at L3. They conducted the study on 10 LBA patients via a Paraspinal surface electromyographic (SEMG) scanning technique (4).

References:
1. Al-Eisa E et al Spine (Phila Pa 1976). 2006 Mar 1;31(5):E135-43.
2. Al-Eisa E et al; Spine (Phila Pa 1976). 2006 Feb 1;31(3):E71-9.

3. van Wingerden JP et al; Spine (Phila Pa 1976). 2008 May 15;33(11):E334-41.
4 Leach RA et al; J Manipulative Physiol Ther. 1993 Mar-Apr;16(3):140-9.

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