Diagnosis and symptoms6 min read
What is lumbar flattening and what does it mean on an X-ray?
'Loss of lumbar lordosis' appears frequently on X-rays taken for back pain and is generally perceived as more serious than it is. What the finding means, and why its relationship to pain is complex, is set out below.
The natural curve of the lower back
The lumbar spine normally has a gentle inward curve, distributing the body's weight evenly across the discs and facet joints. As the curve reduces, load distribution changes and some structures are strained more.
The most common cause of flattening is protective muscle spasm from pain. A painful back tightens its muscles, and an X-ray taken during that tightening shows a flattened curve.
This type is temporary. The curve usually returns once pain and spasm resolve, so an X-ray taken during acute pain may not show a permanent structure.
Increased lordosis is also a finding
An excessive curve disturbs load distribution as much as a reduced one. In increased lordosis, pressure on the facet joints rises and back pain that emerges with prolonged standing can appear.
Increased lordosis is often seen with weak abdominal muscles, tight hip flexors and altered pelvic position. These three are assessed together.
At either extreme, the aim is not to bring the curve to a particular number. It is the capacity of the trunk to carry load in a controlled way and to change position.
The relationship between the finding and pain
Flattening and increased lordosis are frequently seen on X-rays of people without back pain, so the measured angle alone does not make a diagnosis.
What determines pain is the trunk muscles' capacity to carry daily load and how often the person changes position. These two variables are stronger predictors than the angle.
The treatment aim is therefore not to correct the curve. Most patients become pain-free without the appearance on the X-ray changing.
Key points
- Lumbar flattening is usually the result of pain rather than its cause.
- Spasm-related flattening is temporary and the curve returns as pain settles.
- Increased lordosis also raises load on the facet joints.
- Flattening and increased lordosis are common in people without pain.
- The aim is not to correct the curve but to raise the trunk's load capacity.
Frequently asked questions
Does lumbar flattening cause a herniation?
No direct causal relationship has been shown. Flattening alters disc load somewhat, but genetic predisposition, age and loading pattern are more decisive in herniation.
Can the curve return?
In spasm-related cases it usually does. In structural flattening established over years the angle largely stays the same, but that does not mean the pain will be permanent.
What mattress should I use?
A medium-firm mattress suits most people best. A very firm one does not support the shoulder and hip prominences, while a very soft one lets the trunk sink.
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This content is for information only and does not replace medical diagnosis or treatment. Response to treatment varies between individuals. Please consult a healthcare professional about your symptoms.