Goal of the Study?
In this systematic review and meta-analysis article from the open-access journal Medicine 1, the authors’ goal was to examine published literature and determine the current state of research into methodologies for diagnosing lumbar segmental instability.
Why are they doing this study?
Lumbar Segmental Instability (LSI) is due to a pathologic movement of the vertebral body on the vertebra below and often causes clinical symptoms. Overall there has been a variety of research into developing diagnostic methodologies for LSI, and many have been successful, although no consensus has yet to be reached.
What was done?
An initial search using nine different clinical research databases resulted in 86 articles covering the search terms “lumbar instability OR lumbar spondylolisthesis” AND “image OR diagnosis”. After removing duplicates, non-English, non-full text and inappropriate articles, 39 full-text articles were analyzed. The various modalities used to diagnose LSI in these 39 studies included dynamic X-rays, facet joint degeneration and physical examination tests.
What did they find?
- Dynamic X-rays in flexion and extension was the most common and widely recognized method to detect the presence of LSI. The major issue with this technique is that the range of segmented vertebral mobility is relatively wide. Research suggested using a sagittal translation of segmented vertebral of ≥ 4 mm or ≥ 8% and a sagittal rotation of ≥ 10° in the L1 to L5 and ≥ 20° in L5 to S1. Research also indicated that supine-prone dynamic X-ray has a better diagnostic value than flexion-extension images. A new kind of semi-automatic X-ray device called a Vertebral Motion Analysis (VMA) system shows an overall improvement in specificity, sensitivity, consistency and negative predictive value compared to traditional dynamic flexion imaging.
- The facet joint effusion found by a lumbar MRI is also a good indicator for predicting LSI and helpful for determining the severity of the lumbar instability. The change in facet joint space may be another effective modality to predict LSI but it needs further research.
- In general physical examination or assessment, questionnaires are supposed to be an important means of auxiliary diagnosis of LSI. They are simple and economical, but the subjective error is much larger, so the research conclusions are controversial and the repeatability is poor. This greatly erodes their effectiveness.
L2-5 Hypermobility Model demonstrating instability, if desired.
Why do these findings matter?
A variety of causes such as; degenerative disease of the discs and/or facet joints, spinal deformity, lesions of muscle and/or fascia and even psychological factors is thought to give rise to low back pain. LSI is merely the biomechanical failure of a lumbar segment and does not necessarily correlate with the degree of a patient’s pain. The topic of chronic instability of the lumbar spine is subject to much debate as to the exact nature of the problem, the correlation with symptoms or the relevance to patient management. For clinicians to make treatment choices it will be necessary to have a targeted diagnostic methodology. The authors feel that the diagnosis of LSI will become easier and more accurate in the future.
At Dynamic Disc Designs, we have developed anatomical models to help clinicians explain the symptoms related to lumbar segmental instability.