Lower Extremity Peripheral Nerves: How VA Rates Sciatic & Leg Nerves

The sciatic nerve is the largest nerve in the body, innervating the hamstring muscles and branching into the common peroneal and tibial nerves below the knee. Under DC 8520, complete paralysis is rated at 80%, characterized by foot drop, complete loss of knee flexion, a completely flail foot, and extensive calf muscle atrophy. Severe incomplete paralysis is rated 60%, marked by severe muscle weakness and widespread sensory loss. Moderately severe incomplete is rated 40%; moderate incomplete is rated 20%; and mild incomplete (sensory tingling and minor motor weakness) is rated 10%.

The common peroneal nerve (external popliteal nerve) innervates the muscles that dorsiflex and evert the foot and extend the toes. Under DC 8521, complete paralysis is rated 40%, characterized by foot drop, inability to dorsiflex the ankle or toes, and an equinovarus deformity that produces a high-steppage gait. Severe incomplete paralysis is rated 30%; moderate incomplete is rated 20%; and mild incomplete is rated 10%. Veterans requiring an ankle-foot orthosis (AFO) brace to walk typically meet the severe or complete threshold.

The femoral nerve innervates the quadriceps femoris muscle group, controlling active knee extension, and supplies sensation to the anterior thigh and medial lower leg via the saphenous nerve. Under DC 8526, complete paralysis is rated 50%, characterized by paralysis of the quadriceps, complete inability to extend the knee, and leg instability causing frequent falls. Severe incomplete paralysis is rated 30%; moderate incomplete is rated 20%; and mild incomplete is rated 10%.

The tibial nerve (internal popliteal nerve) innervates the gastrocnemius, soleus, and deep posterior calf muscles, controlling plantar flexion of the foot and toe flexion. Under DC 8522, complete paralysis is rated 40%, characterized by inability to push off with the foot, loss of toe flexion, and a calcaneovalgus deformity with sensory loss along the sole of the foot. Severe incomplete paralysis is rated 30%; moderate incomplete is rated 20%; and mild incomplete is rated 10%.

Lower extremity nerve impairment is one of the most common secondary disability claims in the VA system. Under 38 CFR 3.310, herniated intervertebral discs, degenerative disc disease, or spinal stenosis at L4-L5 and L5-S1 frequently pinch descending nerve roots, causing radiating sciatic or femoral radiculopathy. Ratings for radiculopathy are awarded in addition to the primary rating for lumbar limitation of motion without violating pyramiding rules.