What is the difference between the original and modified Schober's (Schober's test) tests?

Difference Between Modified Schober's Test and Modified-Modified Schober's Test

The main difference between the Modified Schober's test and the Modified-Modified Schober's test is in their measurement landmarks and technique, with the Modified-Modified Schober's test showing higher reliability for measuring lumbar flexion and extension.

Original and Modified Schober's Test

• The original Schober's test measures lumbar flexion by marking a point at the lumbosacral junction and measuring 10 cm above this point in standing position, then measuring the increase in distance between these points during forward flexion 1
• The Modified Schober's test (MSI) uses different reference points: it marks a point at the lumbosacral junction, then measures 5 cm below and 10 cm above this point (total 15 cm) in standing position, and measures the increase during forward flexion 2
• The Modified Schober's test is included in the core set for clinical record keeping in ankylosing spondylitis by the Assessment of SpondyloArthritis international Society (ASAS) 3

Modified-Modified Schober's Test

• The Modified-Modified Schober's test (MMST) uses different landmarks: it places marks at the posterior superior iliac spines (PSIS) and 15 cm above this point, then measures the change in distance during flexion 4, 5
• This test was developed to improve reliability by using more easily identifiable anatomical landmarks (PSIS) compared to the lumbosacral junction used in the original and modified versions 4
• The MMST has demonstrated excellent test-retest reliability with intraclass correlation coefficients ranging from 0.78 to 0.89 for lumbar flexion and 0.69 to 0.91 for extension 4

Reliability and Validity Comparison

• The Modified-Modified Schober's test shows higher intra-rater reliability (ICC=0.95) and inter-rater reliability (ICC=0.91) compared to the Modified Schober's test 5
• Recent studies confirm the MMST has high reliability for both lumbar flexion (ICC 0.94) and extension (ICC 0.95) in patients with lumbar radiculopathy 6
• The MMST demonstrates moderate validity when compared with radiographic measurements (r=0.67) 5
• The Modified Schober's test shows only weak to moderate correlation with radiographic measurements of lumbar mobility (r=0.333) 2

Clinical Applications

• Both tests are recommended by the American College of Rheumatology for assessing spinal mobility in spondyloarthropathies 3
• The European League Against Rheumatism (EULAR) includes these tests in their core set of measurements for assessing physical function in patients with ankylosing spondylitis 3
• When used together with the Fingertip-to-Floor Distance (FFD) test, these tests provide more comprehensive assessment of lumbar flexion as they measure different aspects of the same movement 7

Practical Considerations

• The MMST has a minimum metrically detectable change of 1 cm, meaning changes greater than this can be considered true clinical changes rather than measurement error 5
• The MMST is preferred in clinical settings due to its more easily identifiable anatomical landmarks, which contributes to its higher reliability 4, 6
• Both tests have excellent intra-rater reliability, but the MMST shows superior inter-rater reliability, making it more suitable for settings where multiple clinicians assess the same patient 4, 5

Limitations

• Neither test fully correlates with radiographic measurements of lumbar spine angular motion, suggesting they may not perfectly reflect true spinal mobility 2
• The MMST was found to reflect spinal mobility better than the original Schober's test, though both have limitations in accurately measuring lumbar spine angular motion 2
• When used alone, either test provides incomplete information about lumbar mobility and should be combined with other assessment methods for comprehensive evaluation 7