Lower Extremity Pain In A Recreational Hiker

HISTORY: A 60-year-old female recreational hiker with history of right knee medial meniscus tear status post meniscectomy over ten years ago presented with right lower extremity pain. She typically hiked 3-4 miles a day. For two weeks, she endorsed a worsening, intermittent burning sensation originating at the lateral aspect near the fibular head that radiated to the fifth toe. Pain was refractory to oral analgesics, worse with activity, and improved with rest. She denied muscle weakness, back/buttock pain, or frequent leg crossing. PHYSICAL EXAMINATION: BMI: 21.5. Non-antalgic gait. Full motion of lumbar spine with no tenderness in lumbar region. No erythema, swelling or ecchymosis. Non-tender over the proximal fibular head. Normal motion of lower extremity joints. Full sensation and strength of lower extremity dermatomes and myotomes. Negative fibular head Tinel’s. DIFFERENTIAL DIAGNOSIS: 1. Peroneal nerve entrapment. 2. Peripheral neuropathy. 3. Lumbar radiculopathy. 4. Exertional compartment syndrome. 5. Peripheral arterial disease TEST AND RESULTS: Lower Extremity EMG: Right superficial peroneal mononeuropathy with borderline motor unit changes in distal muscles. MRI Right Tib/Fib: Lipomatosis of the peroneal nerve as it passes about the fibular head without distal muscle atrophy. FINAL WORKING DIAGNOSIS: Superficial peroneal nerve mononeuropathy likely secondary to lipomatosis of the nerve. TREATMENT AND OUTCOMES: 1. Referred to physical therapy. 2. Symptoms worse one month later. Peroneal nerve diagnostic ultrasound with no obvious signs of lipomatosis or entrapment. 3. Still worsening two months later. Referred for ultrasound guided hydro-dissection of common peroneal nerve with 4 mg dexamethasone and 15 ml D5W 5%. 4. No improvement. Referred to orthopedic surgery. Plan to undergo right leg peroneal nerve decompression, superficial and common peroneal nerve neurolysis, anterior and lateral compartment fasciotomy.