The Clinical Value of Assessing Lumbar Posteroanterior Segmental Stiffness: A Narrative Review of Manual and Instrumented Methods.

Abnormal spinal segmental motion/stiffness is purported to be a cause, or an effect of, low back pain. Therefore, the assessment of posteroanterior segmental spinal stiffness is a common practice in clinical and research settings. In clinical settings, manipulative practitioners routinely assess spinal stiffness manually to guide clinical decision-making. Unfortunately, the reliability of manual segmental spinal stiffness assessment is poor. As a result, various spinal stiffness-testing devices have been developed to improve the reliability and accuracy of spinal stiffness measures. Although previous critical and systematic reviews have summarized the evidence regarding the reliability and confounding factors of manual and/or instrumented spinal stiffness measurements, no available review has summarized the principles of various spinal stiffness measurement methods nor pragmatic recommendations to optimize these measurements. Importantly, although posteroanterior segmental spinal stiffness is hypothesized to be related closely to low back pain or clinical outcomes after treatments, no review has been conducted to summarize evidence related to these premises and to discuss factors that can confound these relations. Against this background, this narrative review revisits the concept of both manual and instrumented spinal stiffness assessments, summarizes the pragmatic recommendations for minimizing measurement errors, reviews the potential relations between segmental spinal stiffness and low back pain, and provides future clinical research directions that can benefit clinicians and researchers alike. LEVEL OF EVIDENCE: Not applicable.