A patient with a disc protrusion at L5-S1 would most likely present with which finding?

• A. Microtears of the ligamentum flavum
• B. Lumbar facet joint arthropathy
• C. Soft tissue strain of the lumbar extensors
• D. Posterolateral disk protrusion at L5-S1

Answer: (D)

A posterolateral disk protrusion at L5-S1 tends to compress the S1 nerve root, producing radicular symptoms in the S1 distribution. This typically includes pain that travels down the posterior leg to the heel and sole, possible sensory loss on the lateral foot, weakness of plantarflexion (gastric-soleus), and a decreased or absent Achilles reflex. These signs reflect nerve-root compression rather than isolated muscle or joint pathology. Local back muscle strains, ligament or facet problems can cause back pain or stiffness but don’t create the same dermatomal and reflex changes seen with S1 radiculopathy. Hence, the presentation aligns with a disc protrusion at L5-S1 affecting the S1 nerve root.