You measure lumbar multifidus stiffness at a fixed site, from a baseline, with consistent probe placement. The two practical methods are a handheld myotonometer, which reads stiffness in seconds, and shear wave elastography, which uses ultrasound to reach deeper tissue. A 2024 study of adults with low back pain reported intraclass correlation coefficients at or above 0.94 for the multifidus with a handheld device, which is excellent reliability.
Where is the multifidus and why measure it?
The lumbar multifidus is a deep spinal muscle that runs alongside the vertebrae and is most accessible around L4-5. It sits under the erector spinae and the thoracolumbar fascia. It matters clinically because its mechanical state tends to change in chronic low back pain, and because a stiffness number gives you and the patient something to track between visits.
A 2024 shear wave elastography study of 30 patients with chronic non-specific low back pain found multifidus stiffness at L4-5 was significantly higher than in healthy controls and moderately correlated with pain, around r = 0.42 to r = 0.50. The muscle is a real signal, but a moderate one, which is why it is best used alongside other readings rather than alone.
Which measurement method should you use?
| Method | Depth reached | Time per site | Best fit |
|---|---|---|---|
| Handheld myotonometry | Superficial to mid | Seconds | Routine chiropractic re-exams |
| Shear wave elastography | Deep | Minutes, needs ultrasound | Research and imaging-equipped clinics |
| Palpation | Practitioner-dependent | Seconds | Screening, no number produced |
For a chairside chiropractic workflow, a handheld device is the practical choice. It produces a number in seconds without imaging. The tradeoff is depth: it reads the more superficial portion of the multifidus, while shear wave elastography reaches the deeper fibers.
How do you get a reliable reading?
Reliability lives in consistency. Position the patient prone with the lumbar spine in a neutral, relaxed posture. Find the same landmark each visit, typically the multifidus just lateral to the L4-5 spinous process. Keep the probe angle perpendicular to the skin and take several readings, then average them.
Deeper tissue and thick overlying fat lower reliability, so a consistent site and light, repeatable contact matter more here than on a superficial muscle. Compare each patient to their own baseline, not to a population reference, because individual anatomy varies.
What else changes a multifidus reading?
The muscle is not the only variable. A 2024 study of deep lumbar muscle stiffness using shear wave elastography reported that female sex and physical inactivity were associated with higher stiffness in the psoas major and quadratus lumborum, and that the method was reliable with good-to-excellent intraclass correlations. The lesson carries to the multifidus: standardize posture and recent-activity conditions, and read change within a patient rather than across patients.
Survey data: In a 2026 survey of 455 patients who stopped chiropractic care early, 58% cited perception-based reasons: 36% felt no progress, and 22% felt better and self-discharged. A multifidus stiffness reading that is still above baseline gives you a concrete answer when a patient says the problem feels resolved.
How do you use the reading at re-exam?
Record the baseline multifidus reading at the first visit. At re-exam, measure the same site and show the two numbers together. Say: "Your multifidus stiffness reading went from 58 to 50 over four visits. That is measurable change in the muscle, separate from how your pain feels."
Keep the claim tied to the number. "Your reading is still above baseline" is supported. "Your muscle is still injured" is not. The measurement tracks a mechanical property, not a diagnosis.
Frequently Asked Questions
How do you measure lumbar multifidus stiffness?
Two methods are practical. A handheld myotonometer taps the tissue and reads stiffness in seconds at a fixed site. Shear wave elastography uses ultrasound to quantify deeper stiffness in the clinic. Both require a baseline reading and consistent probe placement so re-exam comparisons mean something.
Where is the lumbar multifidus and why measure it?
The multifidus is a deep spinal muscle running alongside the lumbar vertebrae, most accessible around L4-5. It is measured because its stiffness tends to be elevated in chronic low back pain and because it gives a re-exam number that a pain scale cannot provide.
Is stiffness measurement of the multifidus reliable?
Reliability is good for accessible spinal muscles when probe placement is consistent. A 2024 study of physically active adults with low back pain reported intraclass correlation coefficients at or above 0.94 for the lumbar multifidus with a handheld device. Deeper tissue and thick overlying fat lower reliability.
Does higher multifidus stiffness mean more pain?
Not reliably at the individual level. A 2024 shear wave elastography study found multifidus stiffness was higher in low back pain patients and moderately correlated with pain, but stiffness and pain are separate signals that often diverge. Use the reading to track change over time, not to grade pain.
How long does a multifidus stiffness measurement take?
A handheld reading takes seconds per site once the patient is positioned prone. The time cost is in consistent setup: same posture, same landmark, same probe angle each visit. That consistency is what makes the baseline-to-re-exam comparison valid.
What affects a multifidus stiffness reading besides the muscle?
Posture, recent activity, sex, and overlying tissue thickness all influence readings. One 2024 study found female sex and physical inactivity were associated with higher deep lumbar muscle stiffness. Standardize position and compare each patient to their own baseline rather than to a population norm.
Do I need ultrasound to measure multifidus stiffness?
No. Shear wave elastography is the research standard and reaches deeper tissue, but a handheld myotonometer is faster and more practical for a routine chiropractic visit. The tradeoff is depth: handheld devices read the more superficial portion of the muscle.
Citations
- Shear wave elastography based analysis of changes in thoracolumbar fascia and lumbar muscle stiffness in chronic non-specific low back pain (2024). Frontiers in Bioengineering and Biotechnology.
https://www.frontiersin.org/journals/bioengineering-and-biotechnology/articles/10.3389/fbioe.2024.1476396/full - Reliability of Ultrasound Shear Wave Elastography for quantifying psoas major and quadratus lumborum stiffness (2024). PubMed PMID 38272743.
https://pubmed.ncbi.nlm.nih.gov/38272743/
One approach is to add a second channel of objective data alongside subjective pain reports. Options include soft tissue stiffness measurement (such as MuscleMap), range-of-motion testing, and posture analysis. Each gives you something concrete to show the patient rather than asking them to take your word for it.