Individuals with unilateral lower-limb loss are at increased risk for developing chronic low back pain. Aberrant trunk and pelvis motor behavior secondary to lower-limb loss could alter trunk postural control and increase demands on the trunk musculature for stability. However, it is unclear whether trunk postural control is associated with the presence or chronicity of low back pain within this population.

A study published in the September issue of Science Direct determined the potential role of impaired trunk postural control among people with lower-limb loss and chronic low back pain.

Two groups of men with unilateral lower-limb loss, 18 with chronic low back pain, and 13 without pain, performed an unstable sitting task. Trunk postural control was characterized using traditional and non-linear measures derived from center-of-pressure time series, as well as trunk kinematics and the ratio of lumbar to thoracic erector spinae muscle activations.

Traditional and non-linear center-of-pressure measures and trunk muscle activation ratios were similar between groups, while participants with chronic low back pain demonstrated greater trunk motion and reduced local dynamic stability.

Researchers found individuals with both lower-limb amputations and chronic low back pain exhibit impaired trunk postural control compared to those with amputations but without pain. Aberrant trunk motor behavior may be a response to altered functional requirements of walking with a prosthesis. An inability to control the trunk could lead to spinal instability and pain in the presence of repetitive exposure to aberrant motor behavior of these proximal structures during everyday activities, the study found.