How to rule out ankylosing spondylitis in cases of lumbar muscle strain

Lumbar muscle strain can be differentiated from ankylosing spondylitis through assessment of chest expansion range, magnetic resonance imaging (MRI), prognosis, and other methods. Specific analyses are as follows:

1. Chest Expansion Range

Lumbar muscle strain typically refers to cumulative injury of the lower back muscles, primarily caused by prolonged heavy loading or similar factors. This leads to aseptic inflammation in the lumbar muscles, resulting in lumbar muscle strain. The lesion is mainly confined to the lumbar musculature and does not affect other tissues. Therefore, chest movements are generally unaffected, and the range of thoracic expansion remains normal. In contrast, during the progression of ankylosing spondylitis, calcification occurs in surrounding tissues and ligaments, causing increasing stiffness of the spine. This results in significantly reduced chest expansion during respiratory movements, helping to distinguish it from lumbar muscle strain.

2. Magnetic Resonance Imaging (MRI)

In patients with lumbar muscle strain, MRI may show soft tissue edema due to inflammatory factor stimulation. Some cases may also reveal calcification spots within the muscles, gradual muscle atrophy, and uneven signal intensity. In patients with ankylosing spondylitis, MRI reveals poor activity at the lesion sites, erosion of local joint bone, sclerotic margins, and progressive thickening of tendons around the affected areas.

3. Prognosis

Patients with mild lumbar muscle strain who receive early treatment and improve lifestyle management usually have a favorable prognosis and can largely regain normal function. In contrast, ankylosing spondylitis currently has no curative treatment; management focuses on controlling disease progression and alleviating pain through medications or surgical intervention.

In addition, differentiation can also be made based on X-ray imaging, range of spinal flexion, and patterns of disease progression. Regular follow-up examinations are recommended, and patients should avoid strenuous physical activities in daily life to prevent worsening of symptoms.