Signs of Quadratus Lumborum as a Pain Generator in Low Back Pain
The quadratus lumborum (QL) muscle should be examined as a potential pain generator in patients presenting with flank pain, low back pain, buttock pain, and lateral hip pain, as it may be a more common source of pain than previously believed.
Clinical Presentation and Diagnostic Signs
Pain Location and Characteristics
- Pain may present in the flank, low back, buttock, and lateral hip regions 1
- Unilateral localized low back pain with paravertebral muscle spasm 2
- Pain may be acute or chronic in nature 1
Physical Examination Findings
- Palpation tenderness over the QL muscle 2
- Decreased lumbar range of motion 2
- Paravertebral muscle spasm 2
- Presence of myofascial trigger points in the QL muscle 3, 1
- Taut bands within the muscle tissue 3
- Tenderness at the tendon attachments (enthesopathy) 3
Functional Assessment
- Altered muscle function of the QL 4
- Changes in direction-specific activity of QL, particularly in the anterior and posterior layers 5
- Redistribution of activity between different regions of the QL muscle in people with low back pain 5
- Biomechanical changes in trunk extension movements 5
Associated Findings
- QL muscle stiffness changes correlate with pain intensity and central sensitization 4
- Greater muscle softness (decreased stiffness) is linked to higher pain intensity and poorer physical quality of life 4
- May coexist with thoracolumbar joint dysfunction 1
- Can present with different patterns of erector spinae activity 5
Diagnostic Considerations
Differential Diagnosis
- Must differentiate from nonspecific low back pain, which accounts for approximately 85% of low back pain cases 6
- Should rule out serious underlying conditions such as cancer, infection, or cauda equina syndrome 6
- Need to distinguish from radiculopathy or spinal stenosis 6
- Consider other specific spinal causes such as vertebral compression fracture or ankylosing spondylitis 6
Assessment Approach
- A focused history and physical examination should determine the likelihood of QL involvement versus other specific underlying conditions 6
- Diagnostic triage helps classify patients into appropriate categories for treatment 6
- Palpation of the QL muscle after identifying key anatomical landmarks is crucial for accurate diagnosis 3
Clinical Implications
Treatment Response
- Response to targeted interventions such as trigger point injections or QL blocks may confirm diagnosis 3, 2
- Improvement in visual analog scale (VAS) scores and Oswestry Disability Index (ODI) following QL-specific treatment supports QL as the pain generator 2
- Myofascial therapy directed at restoring muscle length and function, coupled with joint manipulation to related dysfunctional areas, may be effective 1
Prognostic Factors
- Younger age, female gender, and lower BMI are associated with better responses to QL-specific treatments 2
- Chronicity of symptoms may affect treatment outcomes and number of treatments required 3
Clinical Pitfalls
- QL involvement is often missed in the diagnosis of low back pain, leading to unnecessary diagnostic investigations and chronicization of pain 2
- Thoracolumbar joint dysfunction may coexist with QL myofascitis and must be addressed for optimal results 1
- Altered biomechanics and muscle function patterns may persist if not properly identified and treated 5
By recognizing these specific signs of QL involvement in low back pain, clinicians can provide more targeted and effective treatments, potentially avoiding unnecessary interventions and preventing progression to chronic pain.