Low Back Pain With a Red Flag You Can Feel
A 45-year-old man presents with 3 days of worsening low back pain after lifting a heavy box. Pain is midline lumbar, worse with movement, and radiates to the left buttock but not below the knee. He denies bowel or bladder dysfunction, saddle anesthesia, fever, or trauma. Vitals are normal. Exam: lumbar paraspinal hypertonicity bilaterally, tenderness at L4–L5, negative straight-leg raise, normal strength and reflexes, and normal sensation. You plan osteopathic manipulative treatment (OMT) for mechanical low back pain. Before treatment you perform a focused structural exam and note a positive seated flexion test on the left with a deep left sacral sulcus and a left inferior lateral angle that is more posterior and inferior than the right.
1. What somatic dysfunction do the structural findings indicate, and how does that change your OMT plan?
Read the worked answer
The findings describe a left sacral torsion (left on left)-or at minimum a left unilateral sacral flexion/shear pattern. Reasoning: a positive seated flexion test on the left localizes the dysfunction to the left sacral base; a deep left sacral sulcus and a left ILA that is posterior and inferior indicate the left side has moved into flexion/extension asymmetry consistent with a left-on-left torsion (left oblique axis, left rotation). For a left-on-left torsion, the treatment is counterstrain or muscle energy directed at the left sacral base, or HVLA/muscle energy to reduce the torsion (e.g., patient prone, engage the left oblique axis, and use a flexion/extension barrier). Avoid generic 'lumbar HVLA' without addressing the sacral torsion, which will not hold. Reassess the seated flexion test and landmarks after treatment. Document the somatic dysfunction and the technique used.
2. Before you treat, what must you rule out, and why does the negative straight-leg raise not fully reassure you?
Read the worked answer
You must rule out cauda equina syndrome, fracture, infection, and malignancy-the 'red flag' screen. He denies saddle anesthesia and bowel/bladder dysfunction, which is reassuring, but cauda equina can present without classic symptoms early, and a negative straight-leg raise does not exclude it because SLR is a test for lumbosacral radiculopathy (L4–S1 nerve root irritation), not for central canal compromise. Also, SLR sensitivity is modest and can be negative with a large central disc herniation or with root compression that does not tension the sciatic nerve. Document perineal sensation, anal wink, post-void residual if any urinary symptoms, and bilateral lower extremity strength/reflexes. If any red flag emerges (progressive deficit, saddle anesthesia, urinary retention, fever, IV drug use, cancer history, age >50 with new pain, or trauma), obtain MRI/CT and urgent neurosurgical or medical evaluation rather than proceeding with OMT. OMT is appropriate only for mechanical, red-flag-negative pain.