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Multidetector CT with 3-Dimensional Post-Processing is a Valuable Tool in Detection of Hardware Fail 2006

General Spine

J. Matthew Debnam, M.D., Non ASSR Member
George M. Hunter, M.D., Ph.D., Non ASSR Member
Leena M. Hamberg, Ph.D., Non ASSR Member

Scientific Paper

Purpose

Tumor resection is often performed in patients with primary and metastatic disease of the spine. This may include the placement of metallic and bony hardware for support and stabilization. The hardware construct has routinely been evaluated with plain film radiography. However, with further advances in Multidetector CT (MDCT), including 3-Dimensional post-processing, evaluation of the construct can be performed in multiple planes and with 3-D Volume Rendering and the Translucent Display. The purpose of this study was to review the MDCT imaging findings of hardware failure in five patients who had undergone surgery for a spinal malignancy.

Methods & Materials

Five patients were identified with findings of hardware failure on MDCT imaging. In all 5 patients, previous surgery for resection of a spinal tumor (3 metastatic renal cell carcinoma, 1 metastatic breast carcinoma, 1 sacral chordoma) was performed. These surgeries included, in addition to the tumor resection, vertebrectomy with posterior instrumentation (2 patients), vertebrectomy with anterior instrumentation, bilateral laminectomy with right facetectomy and posterior instrumentation, and total sacrectomy with posterior lumbopelvic stabilization. The imaging, which was performed after tumor resection, included plain film radiographs in 4 patients and MDCT in all 5 patients. Follow-up imaging included MDCT in four of the five patients, the remaining patient opting for conservative management at an outside institution.

Results

All 5 patients with hardware failure presented clinically with back and/or leg pain. The types of hardware failure included the following: posterior migration of a methyl-methacrylate graft, superior migration of a titanium cage, loosening of pedicular screw, anterior migration of metallic cage and dislodgement of an anterior midline screw, and in the fifth patient, collapse of the bony and metallic lumbopelvic stabilization segment. In 3 of 4 patients, corresponding plain film radiographs did not detect the hardware failure. The hardware failure was detected in 5 of the 5 patients on MDCT studies with 3D post-processing. Three of the 5 patients underwent successful revision of the hardware, 1 patient chose conservative management and was followed with MDCT which was stable at one year. The final patient opted to be followed conservatively at an outside institution.

Conclusion

Failure of surgical hardware following tumor resection can have serious complications including pain, deformity, non-union of bony fusion and neurological compromise. It is essential for the radiologist to detect hardware failure when evaluating the post-operative spine. Recent advances in multidetector CT with 3-D post-processing has lead to an increased utilization in evaluating the post-operative spine in the oncologic patient. This has lead to greater detection of hardware failure in this patient population and has shown to be a valuable tool is assessing the post-operative oncologic spine.