Sacral fractures after lumbosacral fusion: a characteristic fracture pattern.

OBJECTIVE: The purpose of this study was to describe the radiologic pattern of sacral fractures after lumbosacral fusion and to identify clinical characteristics relevant to the radiologic diagnosis. MATERIALS AND METHODS: A search of CT, nuclear medicine, and MRI radiology reports over a 5-year period at our institution revealed a total of 23 patients with sacral fractures after lumbosacral fusion. Two radiologists reviewed all of the images to determine the sacral fracture pattern. The clinical records of these patients were reviewed for interval after surgery, fusion length, hardware, approach, preoperative diagnosis, symptoms, treatment, and risk factors. RESULTS: All 23 sacral fractures were horizontal through the sacral body, involved the screw holes, and exited through the posterosuperior sacral alae. The fractures occurred within 3 months of fusion in 19 of 23 patients. All 23 patients had symptoms at the time of fracture. Seventeen of 23 fusions were long (more than four vertebrae). Four of 23 patients had osteoporosis. Eleven of 23 fractures healed without surgery, and 12 were managed with transiliac fixation. CONCLUSION: Sacral fractures after lumbosacral fusion have a characteristic transverse pattern through the sacral screw holes that differs from the configuration of more common sacral insufficiency fractures. Most of these fractures occur within 3 months after surgery, and many of the patients need additional surgical fixation. Because few of the patients had osteoporosis and most underwent long fusion, the fractures might have been caused by hardware-related stress raisers in the sacrum.

Lumbar discal cyst: Diagnostic discography followed by therapeutic computed tomography-guided aspiration and injection.

Discal cysts are extradural masses that communicate with the intervertebral disk and are a rare cause of lower back pain and lumbar radiculopathy. This case report describes a lumbar discal cyst, the diagnosis of which was confirmed on conventional discography, and which was treated with computed tomography-guided aspiration and steroid injection. Several reports have described this procedure, but only one in the radiology literature, and thus the purpose of this report is to remind the radiology community of the existence of this entity and propose a minimally invasive means of treatment.

Imaging of hip arthroplasty.

The imaging evaluation of the prosthetic hip begins with radiography, but arthrography, aspiration, scintigraphy, sonography, CT and MR imaging all have roles in the evaluation of the painful prosthesis. This article will review the appearance of normal hip arthroplasty including hemiarthroplasty, total arthroplasty, and hip resurfacing, as well as the appearances of potential complications such as aseptic loosening and osteolysis, dislocation, infection, periprosthetic fracture, hardware failure, and soft tissue abnormalities.