Management of posterior leg pain referred from conditions of the lumbar spine

The primary aim of this study was to compare the immediate effects of a 3 x 1 minute SLR mobilisation technique on the three different sub-groups of individuals with spinally referred leg pain.

The secondary aim was to establish whether the presence of CS, levels of disability and levels of certain psychosocial factors impacted upon outcome of the SLR treatment.

Preliminary aims from earlier studies were to identify the validity and repeatability of the frame-by-frame cross correlation method of analysing ultrasound images of sciatic nerve excursion, and repeatability of the vibration thresholds and pressure pain thresholds. These measures used in the clinical study were found to be valid and repeatable.

Individuals with spinally referred leg pain of greater than three months duration were recruited from local NHS trusts and the local population and assessed by physiotherapists. Physiotherapists then allocated the participants into one of the three sub-groups after a thorough assessment, and established the presence of CS. Disability and psychosocial questionnaires were given to the participants to complete prior to their attendance at the laboratory. Subjects attended the human movement laboratory and sciatic nerve excursion in the posterior thigh (using ultrasound), pressure pain thresholds, and vibration thresholds were measured before and after a treatment consisting of a 3 x 1 minute SLR mobilisation. The data was analysed using a three-way mixed factorial ANOVA, with subsequent covariate analysis where appropriate.

No significant differences were found for any of the 3 outcome measures between the three groups or before and after the treatment (p>0.05). Vibration thresholds showed a non-significant trend to decrease in the radiculopathy group. This indicates that although no improvement in nerve conduction was seen after treatment; it does not worsen even in individuals with alteration to nerve conduction. Nerve excursion varied markedly between individuals, but a trend for decreased sciatic nerve excursion in the posterior thigh occurred in individuals with leg pain referred below the knee. 

This may suggest that changes to compliance of the nerve root occurred post mobilisation in individuals with nerve root entrapment, however as the nerve root could not be visualised with ultrasound, this is speculative at this time. There were no significant correlations between the psychosocial factors and level of disability and the three outcome measures and no baseline differences in these factors between the three groups, indicating that these factors did not impact on outcome. Only two participants were identified as having CS, and therefore it is not possible to ascertain the effect on outcome from this factor in this study.