Clinical tests to diagnose lumbar segmental instability: a systematic review.
Alqarni AM, Schneiders AG, Hendrick PA. J Orthop Sports Phys Ther. 2011;41(3):130-40.
Many clinicians find treating low back pain a challenge. One management strategy is to classify patients with low back pain into subgroups (for example, structural lumbar segmental instability). There are several clinical tests that have been proposed to diagnose these subgroups; including structural lumbar segmental instability. Structural lumbar segmental instability is characterized by the loss of the spine’s ability to maintain normal segmental motion during normal activities/loading. The instability may be caused by various factors (for example, disc degeneration, postoperative spinal fusions, recurrent low back pain) and coexist with others (for example, facet joint hypertrophy, osteophyte formation). But, what if the tests designed to stratify patients into subgroups (patients with lumbar segmental instability) for particular treatments were not accurate? This systematic review evaluated the diagnostic accuracy of clinical tests for diagnosing patients with structural lumbar segmental instability. Among the four articles that were analyzed, 11 clinical tests were included (e.g., sit to stand test, passive accessory intervertebral movements, posterior shear test, prone instability test, passive physiological intervertebral movements). Many tests had high specificity (specificity: not falsely diagnosing a healthy patient) but low sensitivity (sensitivity: positively diagnose a patient who has pathology). So, overall these tests were not great at determining if a patient with structural lumbar segmental instability had the condition. The passive lumbar extension test was by far the most accurate clinical test (sensitivity = 84%, specificity = 90%).
In rehabilitation, we often make our decision based on clinical history and our evaluations of functional limitations and symptoms. In a recent post, I described a study which indicated that our medical history screening needs to be more thorough and this study highlights the need for us to reassess some of the special/stress tests we use. Even the best clinician can’t develop an optimal treatment program with bad information. If we believe in classifying patients with low back pain to optimize our treatments then we need to be able to properly identify these subgroups. This study helps clinicians figure out the most effective test (passive lumbar extension test) to perform to determine if a patient has lumbar segmental instability. This type of systematic review and research can be very valuable to clinicians to help them improve the effectiveness and efficiency of their evaluations. This is a good example of when evidence based medicine research can be really helpful for us.
Written by: Jeffrey B Driban
Reviewed by: Stephen Thomas