Disclosures: Erika T. Yih, MD: Nothing to disclose

Case Description: The patient woke up with 9/10 right gluteal and lateral leg pain, as well as numbness in her shin and dorsum of her foot after a day of increased manual labor at work. She described feeling like her right leg was going to give out. She denied back pain and bowel/bladder symptoms. Gait examination revealed right circumduction, right foot drop, and inability to heel walk or toe walk on the right side. The rest of her exam was notable for bilateral genu valgum (right greater than left) and tenderness to palpation in the right gluteal musculature.

Setting: Outpatient Musculoskeletal Clinic

Patient: A 65-year-old woman with history of bilateral severe right>left genu valgum and lateral compartment knee osteoarthritis.

Assessment/Results: The patient was prescribed a methylprednisolone dose pack and gabapentin for suspected lumbosacral radiculopathy. However, lumbar spine magnetic resonance imaging (MRI) was negative, and 2 weeks later she continued to have symptoms. Electromyography was performed and was suggestive of peroneal neuropathy at the right knee with concomitant lumbar plexopathy. Pelvic MRI was also ordered and ultimately revealed focal bone marrow edema of the anterior right sacroiliac joint, directly subjacent to an area of increased size and signal of the right sciatic nerve. After being fitted with a knee unloader brace and foot-up brace, the patient’s symptoms gradually improved.

Discussion: Lumbar radiculopathy, lumbosacral plexopathy, and peroneal nerve compression are highest on the differential diagnosis for foot drop with lower leg pain and sensory loss. However, this case study shows that altered biomechanics can lead to reactive edema at the sacroiliac joint and compression of the sciatic nerve, resulting in a similar presentation.

Conclusion: It is important to consider sciatic nerve compression from sacroiliac joint inflammation as a cause for foot drop with leg pain and numbness, particularly in patients who have altered biomechanics due to other pathologies.

Level of Evidence: Level V

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PM&R Meeting Abstracts - https://pmrjabstracts.org/abstract/foot-drop-caused-by-sciatic-nerve-compression-from-reactive-edema-at-the-sacroiliac-joint-a-case-report/