Prone Instability Test
Original Editor - Jennifer Babb and Valerie Ross
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Purpose
To test for the likelihood of a patient with low back pain responding to a stabilization exercise program[1].
The prone instability test is to assess whether there is lumbar spine instability, which can be a contributing factor to low back pain. Specifically, the test helps identify abnormal motion between vertebrae in the lower spine (lumbar region) that may indicate conditions like spondylolisthesis, ligamentous injury, or other spinal disorders that lead to instability.
Key purposes include:
- Assessing Spinal Instability: The test helps to determine if the vertebrae are excessively mobile due to weakened ligaments or faulty structures, which could lead to abnormal motion and pain.
- Differentiating Mechanical Back Pain: It helps distinguish between mechanical back pain (e.g., from muscle strain) and pain caused by structural instability or conditions like spondylolisthesis, where the vertebrae can shift out of place.
- Guiding Treatment: If the test suggests instability, it may guide the clinician toward specific treatments, such as strengthening exercises, bracing, or even surgery (in severe cases). It can also help inform decisions regarding conservative versus more invasive interventions.
- Identifying the Level of Instability: By checking different lumbar segments, the test can help pinpoint the exact area of the spine that may be unstable and is contributing to the patient's symptoms.
- Predicting Prognosis: In certain cases, if instability is identified, it may provide insight into the long-term management of the condition and the likelihood of recovery with conservative treatments versus the need for surgical intervention.
Technique
The patient lies prone with the body on the examining table and legs over the edge and feet resting on the floor. While the patient rests in this position with the trunk muscles relaxed, the examiner applies posterior to anterior pressure to an individual spinous process of the lumbar spine. Any provocation of pain is reported. Then the patient lifts the legs off the floor (the patient may hold table to maintain position) and posterior to anterior compression is applied again to the lumbar spine while the trunk musculature is contracted.[1][2]
The test is considered positive if pain is present in the resting position but subsides in the second position, suggesting lumbo-pelvic instability. The muscle activation is capable of stabilizing the spinal segment.
Evidence
Reference standard success with stabilization exercise program[3].
Sensitivity = .72 - LR = .48
Specificity = .58 + LR = 1.7
This test should be used in conjunction with other tests to confirm the signs and symptoms of lumbar instability. This test also was included in the clinical prediction rule developed by Hicks for patients with favorable responses to spinal stabilization exercise. Therefore, positive test results were correlated with patients with favorable responses, and negative test results were correlated with patients without favorable responses to spinal stabilization exercise programs. This test was one of four variables identified and reported in CPR for lumbar spinal stabilization exercise program success and failure.[4]
Resources
References
- ↑ 1.0 1.1 Flynn T, Cleland J, Whitman J. User's Guide to the Musculoskeletal Examination: Fundamentals for the Evidence-based Clinician. Buckner, Kentucky: Evidence in Motion; 2008.
- ↑ Dutton, M. Orthopaedic Examination, Evaluation, and Intervention. New York: The McGraw-Hill Companies, Inc.; 2008.
- ↑ Hicks G, FritzJ, Delitto A, McGill S. Preliminary development of a clinical prediction rule for determining which patients with low back pain will respond to a stabilization exercise program. Arch Phys Med Rehabil 2005;86:1753-1762.
- ↑ Fritz JM, Piva SR, Childs JD. Accuracy of the clinical examination to predict radiographic instability of the lumbar spine. Eur Spine J. 2005;14(8):743–50.