Changes in Spinal Height Following Sustained Lumbar Flexion and Extension Postures: A Clinical Measure of Intervertebral Disc Hydration Using Stadiometry

Abstract 

Background

Decreased intervertebral disc height can result in diminished load carrying capacity of the spinal segment. Clinical means of assessing postures able to rehydrate the discs were investigated.

Objective

The purposes of this study were 3-fold: (1) to determine if our test protocol using a commercially available stadiometer demonstrated findings consistent with prior laboratory-based protocols; (2) to determine if hyperextension in the prone position and trunk flexion in the supine position caused increased spine height after sustained loading; and (3) to compare the effects of hyperextension in the prone position and trunk flexion in the supine position on spine height changes after a period of sustained loading.

Methods

This study used a pretest, posttest crossover design. Ten women and 11 men (mean age, 24 ± 2.6 years) participated. Subjects held either 10 minutes of hyperextension in the prone position or 10 minutes of trunk flexion in the supine position in the recovery phase. Spine height was measured using a commercially available stadiometer. Spinal height change was determined from measurements taken after loaded sitting and measurements taken after hyperextension in the prone position and trunk flexion in the supine position.

Results

A 1-sample t test indicated no significant difference existed between our mean height change after 5 minutes of sitting and previously published validated findings. A paired t test indicated significant increase in height after both supine flexion and prone extension lying (P< .0001). The mean height gain was 3.11 mm using prone extension and 3.19 mm using the supine flexion protocol. A paired t test indicated no significant difference between these 2 recovery positions (P = .927).

Conclusion

The stadiometer measurement protocol demonstrated that hyperextension in the prone position and trunk flexion in the supine position were easily effective positions for the temporary recovery of spine height after sustained loading. These findings lay the foundation for future research into the viscoelastic creep properties of the intervertebral disk under loading and therapeutic conditions.

Key Indexing Words: Intervertebral Disk, Spine, Prone Position, Supine Position, Load-Bearing