A Retrospective Review of Contrast Nephropathy in a General Population.

BACKGROUND: One of the adverse events associated with administration of intravenous (IV) contrast media is contrast-induced nephropathy, yet its incidence is poorly characterized. We investigated the incidence of contrast-induced nephropathy in patients with elevated baseline serum creatinine concentrations who underwent computed tomography (CT) using IV contrast media. MATERIALS AND METHODS: Using the electronic medical records at a community hospital, we retrospectively identified patients with elevated baseline serum creatinine concentrations who had undergone CT utilizing IV contrast media between January and July 2000, a period prior to the routine use of pretreatment as prophylaxis against contrast-induced nephropathy, and who subsequently developed elevated serum creatinine. We identified concomitant risk factors for the rise in serum creatinine in these patients aside from IV contrast media exposure. RESULTS: One hundred ninety-three patients with a baseline serum creatinine concentration greater than 1.2 mg/dL underwent 236 CT studies utilizing IV low-osmolar contrast media. Nine of the 193 patients had a rise in serum creatinine ≥ 0.5 mg/dL up to 1 month later. None of these 9 patients had contrast exposure as the only risk factor for their rise in serum creatinine. CONCLUSION: The role of IV contrast media in causing contrast-induced nephropathy and, thus, acute kidney injury, may be overestimated. Further study needs to be done into whether contrast-induced nephropathy is truly a common or even a real entity in patients receiving IV contrast media for routine studies who have no other risk factors for kidney injury warranting the expense, risks, and inconvenience of pretreatment.

Prevention of vertebral body-splitting fractures after multilevel ProDisc-L implantation.

BACKGROUND: Prior studies of multilevel ProDisc-L (PD-L) implants (Synthes Spine, Inc., West Chester, Pennsylvania) using the standard US technique have used conventional radiography postoperatively. We found vertebral body-splitting fractures (VB-SFs) in interposed vertebral bodies after 5 sequential multilevel PD-L device implantations using the standard US technique. These were identified with postoperative computed tomography (CT) but were not visible on plain radiographs. In an additional patient, we found that a stress-relieving, pilot holes-only technique did not prevent VB-SFs. The 5 patients operated on with the standard technique composed the background series against which we compared the incidence of VB-SFs in patients operated on with a modification of the standard US technique-a combination of stress-relieving pilot holes, removal of cortex in the chisel path, and a fenestrated chisel (PH/CR/FC)-intended to reduce the incidence of VB-SFs in multilevel PD-L constructs. METHODS: Patients receiving multilevel PD-L implants at 2 sites-1 in the United States and the other in Germany-were operated on with the PH/CR/FC technique and their postoperative CT scans evaluated for the presence of VB-SFs. The frequency of VB-SFs in these patients was compared with that of the 5 patients from the background series who were operated on by the standard US technique. The groups' mean sex, age, body mass index, and vertebral body height, as well as average spinal T score, were also compared. RESULTS: No fractures were found in 13 interposed vertebral bodies in 11 patients operated on with the PH/CR/FC technique, as compared with 4 VB-SFs and 1 anterior keel cut-to-anterior keel cut fracture in 5 interposed vertebral bodies in 5 patients operated on with the US technique (P ≤ .001). Although the sample sizes were small, this difference in fracture rate was not associated with sex, age, body mass index, or average spinal T score. At up to 13 months of follow-up of patients in the background series, we found that VB-SFs tend not to bridge with bone, instead forming sclerotic margins. CONCLUSIONS: The PH/CR/FC technique studied reduced the incidence of VB-SF in multilevel PD-L implants. Because previously published multilevel studies did not use postoperative CT scans and because VB-SFs are not visible on conventional radiography, the incidence of VB-SFs in multilevel PD-L applications may be higher than previously reported. Our findings may contribute to prevention of complications in total disc replacement.

A new paradigm for staging pedicle screw-based spinal procedures: rationale, feasibility, safety, and efficacy.

OBJECT: The aims of this study were to present the rationale for and the evolution of a staged, two-procedure paradigm for spinal surgery requiring pedicle screw instrumentation, and to evaluate the feasibility, safety, and efficacy of the technique. METHODS: The rationale for the new algorithm is presented for consideration in the form of unproven hypotheses subject to verification by subsequent studies. The first stage of the two-staged algorithm, performed in an interventional radiology (IR) setting, involves percutaneous placement of either headless pedicle screws or K-wire fragment placeholders of the trajectory for pedicle screws. The second stage, performed days or weeks later, involves open surgical completion of instrumentation placement and other surgical objectives. The techniques for IR percutaneous K-wire fragment and percutaneous screw placement evolved over the duration of the study. Instrumentation was placed in 126 pedicles in 25 patients. Efficacy was equated to the accuracy of screw placement, which was evaluated using computed tomography (CT). Algorithms incorporating correction for metal artifact were developed to determine deviation of the screws and K-wire fragments from proper position. Over 1500 measurements were made to evaluate K-wire fragment and screw position in the 116 instrumented pedicles for which CT data were available. RESULTS: Accuracy of placement (relative to both cortical and pedicle breaches or to only pedicle breaches) was 98 to 100% for K-wire fragments, 96 to 98% for screws following K-wire fragments, and 100% for percutaneous screws. The only adverse consequence of pedicle screw placement by this method was one infection that occurred 8 months postoperatively. CONCLUSIONS: The staged, two-procedure paradigm for pedicle screw placement proved, within the limits of this study, to be feasible, safe, and effective; therefore, the unproven rationale behind the new paradigm merits further evaluation in a larger cohort of patients with randomized, matched controls.