The diagnostic effect from axial loading of the lumbar spine during computed tomography and magnetic resonance imaging in patients with degenerative disorders.

STUDY DESIGN Patients with low back pain, sciatica, and neurogenic claudication were observed during computed tomographic myelography or magnetic resonance imaging in psoas-relaxed position and axially compressed supine position of the lumbar spine. OBJECTIVE To estimate the clinical value of axially loaded imaging in patients with degenerative disorders of the lumbar spine. SUMMARY OF BACKGROUND DATA Computed tomography and magnetic resonance imaging still are performed with the lumbar spine in a supine relaxed position, which results in unloading of the spine and enlargement of the canal. METHODS A device for axial loading of the lumbar spine in computed tomography and magnetic resonance imaging was used. Altogether, 172 patients were examined in psoas-relaxed position and axially compressed supine position of the lumbar spine: 50 patients with computed tomographic myelography and 122 patients with magnetic resonance imaging. If a significant decrease (>15 mm2) in the dural sac cross-sectional area to values smaller than 75 mm2 (the borderline value for stenosis) was found during examination in axial loading, or if a suspected disc herniation, narrow lateral recess, narrow intervertebral foramen, or intraspinal synovial cyst changed to being obvious at the axial loading examination, this was regarded as additional information important for the treatment. RESULTS Additional valuable information was found in 50 of 172 patients (29%) during examination in axial loading. In the different diagnostic groups, additional valuable information was found in 69% of the patients with neurogenic claudication, in 14% of the patients with sciatica, and in 0% of the patients with low back pain. The percentage of additional valuable information increased to 50% in the patients with sciatica, if recommended inclusion criteria for examinations in axial loading were used. A narrowing of the lateral recess causing compression of the nerve root was found at 42 levels in 35 patients at axial loading. CONCLUSION According to the study results, axially loaded imaging adds frequent additional valuable information, as compared with conventional imaging methods, especially in patients with neurogenic claudication, but also in patients with sciatica if defined inclusion criteria are used.