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Nicolas Dea, Anne Versteeg, Charles Fisher, Adrienne Kelly, Dennis Hartig, Michael Boyd, Scott Paquette, Brian K. Kwon, Marcel Dvorak and John Street

Object

Most descriptions of spine surgery morbidity and mortality in the literature are retrospective. Emerging prospective analyses of adverse events (AEs) demonstrate significantly higher rates, suggesting underreporting in retrospective and prospective studies that do not include AEs as a targeted outcome. Emergency oncological spine surgeries are generally palliative to reduce pain and improve patients' neurology and health-related quality of life. In individuals with limited life expectancy, AEs can have catastrophic implications; therefore, an accurate AE incidence must be considered in the surgical decision-making process. The purpose of this study was to determine the true incidence of AEs associated with emergency oncological spine surgery.

Methods

The authors carried out a prospective cohort study in a quaternary care referral center that included consecutive patients admitted between January 1, 2009, and December 31, 2012. Inclusion criteria were all patients undergoing emergency surgery for metastatic spine disease. AE data were reported and collected on standardized AE forms (Spine AdVerse Events Severity System, version 2 [SAVES V2] forms) at weekly dedicated morbidity and mortality rounds attended by attending surgeons, residents, fellows, and nursing staff.

Results

A total of 101 patients (50 males, 51 females) met the inclusion criteria and had complete data. Seventysix patients (76.2%) had at least 1 AE, and 11 patients (10.9%) died during their admission. Intraoperative surgical AEs were observed in 32% of patients (9.9% incidental durotomy, 16.8% blood loss > 2 L). Transient neurological deterioration occurred in 6 patients (5.9%). Infectious complications in this patient population were significant (surgical site 6%, other 50.5%). Delirium complicated the postoperative period in 20.8% of cases.

Conclusions

When evaluated in a rigorous prospective manner, metastatic spine surgery is associated with a higher morbidity rate than previously reported. This AE incidence must be considered by the patient, oncologist, and surgeon to determine appropriate management and preventative strategies to reduce AEs in this fragile patient population.

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Charles Fisher and Juliet Batke

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Tobias Pitzen, Juay Seng Tan, Marcel F. Dvorak, Charles Fisher and Thomas Oxland

Object

To avoid the cost of bone graft substitutes and the morbidity of iliac crest bone graft retrieval, locally harvested vertebral body bone has been used to fill interbody cages. When marginal hypertrophic osteophytes are used, there is little impact on the adjacent vertebrae, but when cancellous bone is removed from the central part of the vertebral body, it is not clear how significantly this procedure weakens the vertebra. The objective of this study was to investigate the immediate mechanical response of the cervical spine after removing bone from the central vertebral body.

Methods

Fourteen cervical functional spinal units (FSUs) (mean age 73.3 years, range 63–90 years) were used. For each FSU, bone mineral density (BMD) was determined using lateral-view dual-energy x-ray absorptiometry studies. The FSUs were assigned to 1 of 2 groups (test group or control group) with an equal distribution of BMD. All specimens received a cage placed into the cleaned disc space. The specimens from the test group had a 5-mm-diameter bone plug removed from the vertebral bodies superior and inferior to the cage-fitted disc. The specimens were loaded in flexion-compression until failure via an eccentric compressive force at 0.25 mm/second.

Results

The yield compression strength was 1149 ± 523 N for the test group and 1647 ± 962 N for the control group (p = 0.25). The ultimate compression strength was 1699 ± 498 N for the test group and 2450 N ± 835 N for the control group (p = 0.06). Force at 4 mm displacement was 1064 N for the test group and 1574 N for the control group (p = 0.15). Displacement at yield compression strength was 4.4 mm for the test group and 4.2 mm for the control group (p = 0.78). There was no significant intergroup difference for any of the studied parameters.

Conclusions

There does not appear to be a significant early biomechanical weakening of adjacent vertebrae caused by aforementioned technique of local bone harvest.

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Jeffrey A. Rihn, Nuo Yang, Charles Fisher, Davor Saravanja, Harvey Smith, William B. Morrison, James Harrop and Alexander R. Vacaro

Object

Magnetic resonance imaging has been proposed as a powerful technique for assessing the integrity of the posterior ligamentous complex (PLC) in spinal trauma. Because MR imaging is often used to determine appropriate treatment, it is important to determine the accuracy and reliability of MR imaging in diagnosing PLC disruption. The purpose of this study is to compare the ability of the radiologist and surgeon to assess disruption of the PLC in the setting of acute cervical and thoracolumbar trauma using MR imaging.

Methods

The components of the PLC in 89 consecutive patients with cervical or thoracolumbar fractures following acute spinal trauma were evaluated using MR imaging by both a musculoskeletal radiologist and an independent spine surgeon and assessed intraoperatively under direct visualization by the treating surgeon. The MR imaging interpretations of the musculoskeletal radiologist and surgeon were compared with the intraoperative report for accuracy, sensitivity, specificity, and positive and negative predictive values. A comparison between the radiologist's and spine surgeon's accuracy of MR imaging interpretation was performed.

Results

The agreement between both the spine surgeon's and radiologist's MR imaging interpretation and the actual intraoperative findings was moderate for most components of the PLC. Overall, the MR imaging interpretation of the surgeon was more accurate than that of the radiologist. The interpretation of MR imaging by the surgeon had negative predictive value and sensitivity of up to 100%. However, the specificity of MR imaging for both the surgeon and radiologist was lower, ranging from 51.5 to 80.5%.

Conclusions

Comparison of the MR imaging interpretations between surgeon and radiologist indicates that the surgeon was more accurate for some PLC components. The relatively low positive predictive value and specificity for MR imaging in assessing PLC integrity suggests that both the surgeon and radiologist tend to overdiagnose PLC injury using MR imaging. This can lead to unnecessary surgeries if only MR imaging is used for treatment decision making.