PR_238: Sciatica Caused by a Sacroiliac Fixation Screw in a Traumatic Transfemoral Amputee: A Case Report

Abstract

Setting: University outpatient clinic. Patient: A 32-year-old man with a transfemoral amputation and persisting neuropathic pain. Case Description: This patient recovered from multiple left-sided fractures following a snowmobile versus automobile collision. However, he continued to experience severe neuropathic pain in his amputated left leg and foot during the 2 years since his initial injury. After multiple unsuccessful medication trials, he presented to our amputee clinic for a second opinion. Assessment/Results: He had swelling and tenderness in the distal stump, so an ultrasound was ordered. It showed a hypoechoic mass at the distal sciatic nerve. Magnetic resonance imaging (MRI) confirmed the presence of a neuroma. Subsequent treatments targeted at the neuroma were unsuccessful, including image-guided anesthetic blocks. He had no history of back pain, but the distribution of his pain resembled the S1 dermatome, so a lumbosacral MRI was ordered. This showed a sacroiliac screw, placed to stabilize a pelvic fracture, intruding into the left S1 neuroforamen. A diagnostic S1 nerve block temporarily relieved his pain, and the screw was subsequently removed. Discussion: A handful of cases have reported sciatica in amputees. The symptoms are usually described as a phantom pain or neuropathic pain in the residual limb and are often refractory to conventional treatments. These symptoms typically occur with back pain, and are distinct from the patient’s usual symptoms. Because of this, this case demonstrates that these findings are not universal. Conclusions: Radiculopathy should be included early in the differential diagnosis of refractory phantom pain in amputees with a history of spine or pelvic instrumentation. It should also be considered in those with a change in their usual pain symptoms. As conventional diagnostic tests are limited, including physical exam and electromyography, fluoroscopically guided injection is a useful diagnostic tool in these patients.