Lumbar decompression to treat foot drop after hip arthroplasty.

Twenty-one patients with spinal stenosis who developed foot drop after total hip arthroplasty were reviewed. Patients with other risk factors for nerve injury, such as dislocation, hematoma, intraoperative limb lengthening, revision surgery, and direct operative trauma, were excluded. Also excluded were patients without symptoms of spinal stenosis. Patients in this series had back and leg pain without weakness before their hip arthroplasty. When foot drop developed and persisted four months after hip arthroplasty, patients were examined with magnetic resonance imaging or myelography and computed tomography. High-grade spinal stenosis was found in each patient. Sixteen patients were treated by lumbar decompression. Twelve patients improved; six had complete recovery of foot drop. None of the five patients who did not have surgery significantly recovered. One patient developed a foot drop in the other leg after undergoing lumbar decompression. Coexisting spinal stenosis may be a risk factor for symptomatic nerve injury during hip arthroplasty. Selected patients may benefit from lumbar decompression surgery.