What is Schober's Test?
Schober's test is a simple bedside measurement using a tape measure to assess lumbar spine flexion by marking the skin over the lower back and measuring the distance change between these marks when the patient bends forward maximally.
Test Procedure and Variations
The test has several variations, all measuring skin distraction over the lumbar spine during forward flexion:
Modified Schober Test (most common): Mark a point at the level of the posterior superior iliac spines (dimples of Venus when present), then mark 10 cm above this point. The patient bends forward maximally, and the distance between marks is remeasured. Normal mobility shows an increase of ≥5 cm (total distance ≥15 cm). 1, 2
Original Schober Test: Uses a 10 cm baseline measurement with expected increase of ≥5 cm during flexion. 3, 4
15-cm Schober Test: An alternative that correlates strongly with the 10-cm version (r=0.89-0.93) but systematically measures 1.5 cm higher, making the tests non-interchangeable. 2
Primary Clinical Application
Schober's test is traditionally used to assess spinal mobility restriction in ankylosing spondylitis and axial spondyloarthritis, not for routine evaluation of lumbar stenosis or degenerative disc disease. 3, 4, 2
The test shows correlation with radiographic progression of ankylosing spondylitis (Spearman correlation coefficients showing significant relationships between restricted mobility and syndesmophytes, apophyseal arthritis, and ossification of spinal ligaments). 4
It is incorporated into the Bath Ankylosing Spondylitis Metrology Index (BASMI) as a component score for monitoring disease progression. 2
Critical Limitations and Validity Concerns
Recent high-quality evidence demonstrates that Schober's test has poor validity for accurately assessing true lumbar spine mobility:
A 2024 study comparing Schober's test to objective device measurements (Epionics SPINE® and Idiag M360®) found only 50% agreement between methods, with sensitivity of 68-80% but specificity of only 36-47%. 1
The test shows only weak correlation with radiographic measurements of actual lumbar spine angular motion (r=0.333-0.363 for L1-S1 mobility in ankylosing spondylitis patients). 3
Skin distraction occurs even over completely immobile bony structures like the sacrum, and the measurement typically captures only 3.5 of the 6 spinal segments (T12-S1), not true "lumbar flexion." 5
Reliability Issues
While intrarater reliability is excellent (meaning the same examiner gets consistent results), several technical problems limit clinical utility:
Interrater reliability is only moderate (r=0.71), meaning different examiners may get different results on the same patient. 5
The anatomical landmarks (dimples of Venus) are completely absent in 26% of patients, making standardized measurement impossible. 5
Lumbar lordosis significantly affects agreement between Schober's test and objective measurements. 1
Appropriate Clinical Use
Schober's test should be used as a monitoring tool for individual patients over time rather than as a diagnostic test for lumbar pathology:
It is most appropriate for tracking progression in known ankylosing spondylitis patients, where serial measurements in the same individual can show worsening restriction. 1, 4
It should NOT be used as a primary assessment tool for patients with suspected spinal stenosis, lumbar disc herniation, or nonspecific low back pain—these conditions require different diagnostic approaches including neurological examination and, when indicated, MRI imaging. 6
For radiculopathy evaluation, the straight leg raise test (sensitivity 91% for disc herniation) is far more clinically relevant than Schober's test. 7