Comparative radiation exposure using standard fluoroscopy versus cone-beam computed tomography for posterior instrumented fusion in adolescent idiopathic scoliosis.

STUDY DESIGN: Retrospective cohort. OBJECTIVE: The objective of this study was to define the intraoperative radiation exposure during freehand surgical technique with fluoroscopic assistance for placement and confirmation of posterior instrumentation in patients with adolescent idiopathic scoliosis and compare data with published values using intraoperative cone-beam computed tomography (CBCT) for similar cases. SUMMARY OF BACKGROUND DATA: The treatment of idiopathic-like scoliosis used freehand placement of posterior instrumentation with fluoroscopic confirmation. Computer-assisted navigation systems coupled with intraoperative CBCT have been introduced to aid in accurate placement of instrumentation. Multiple studies report the improved accuracy of instrumentation using CBCT; however, there is a paucity of information regarding the radiation exposure when using CBCT in comparison with fluoroscopically assisted freehand technique. METHODS: Forty-three idiopathic-like scoliosis operations performed by 4 spine surgeons at an academic institution were retrospectively reviewed. Radiation exposure was recorded intraoperatively for each case. Effective dose was determined using published effective dose to dose-length product conversion factors. Values were compared with previous studies reporting radiation exposure for similar cases using CBCT for intraoperative navigation and confirmation of instrumentation placement. RESULTS: Calculated average effective dose using fluoroscopically assisted pedicle screw placement was 0.189 mSv (range, 0.00029-0.953 mSv; SD = 0.16711) per case. Average radiation exposure time was 26 seconds (SD = 18 s) per case, with an average of 11 vertebral levels fused. The literature reports effective dose for CBCT ranging from 7.29 to 9.72 mSv per case for intraoperative navigation and 14.58 to 19.44 mSv per case for both intraoperative navigation and confirmation of screw placement with CBCT. CONCLUSION: We have demonstrated that the use of standard fluoroscopy results in markedly lower radiation exposure during a standard posterior instrumented fusion for idiopathic-like scoliosis than by the use of CBCT; this conclusion is limited by the retrospective nature of the study and lack of a control group. LEVEL OF EVIDENCE: 4.

The morbidity and mortality of fusions from the thoracic spine to the pelvis in the adult population.

STUDY DESIGN: A retrospective analysis. OBJECTIVE: To quantify the risks of surgery and explore the associations of early perioperative complications with patient demographics and surgical variables. SUMMARY OF BACKGROUND DATA: Long fusions extending from the thoracic spine to the pelvis in adults are increasingly common. Currently, there are few studies detailing the overall risks of such comprehensive reconstructions or how preoperative demographics may be associated with potential complications. METHODS: A retrospective study was performed at two tertiary referral institutions. Preoperative patient demographics and intraoperative surgical variables were analyzed to explore the potential association with outcomes. The outcomes recorded were death, length of hospital and intensive care unit (ICU) stay, discharge to a rehabilitation facility, major medical complications, neurologic deficits, and the additional unplanned surgeries that patients subsequently underwent. RESULTS: One hundred three consecutive patients underwent a fusion extending from the thoracic spine to the pelvis for degenerative conditions from 2003 to 2007. There was a 4% mortality rate. The mean hospital stay and mean ICU stay was 12 ± 7 and 2.7 ± 4 days, respectively. Fifty-eight percent of patients were discharged to a rehabilitation facility. Twelve percent of patients experience at least one major medical complication. Seventeen percent of patients had a documented new persistent neurologic deficit that was still present at the final clinic visit. Thirty-five percent of patients underwent at least one unplanned return to the operating theater. There were no perioperative demographics or surgical variables that had a statistically significant association with mortality. Major medical complications were associated with the American Society of Anesthesiologists' (ASA) score (P = 0.030) and the Charlson Comorbidity Index (P = 0.028) but not age (P = 0.273). CONCLUSION: Complex spine reconstruction involving fusions from the thoracic spine to the pelvis continues to be a high-risk procedure in spite of more advanced surgical and perioperative techniques.

University of Washington orthopedic resident experience and interest in developing an international humanitarian rotation.

An academic orthopedic residency program can have a significant impact on the burden of musculoskeletal disease in low- and middle-income countries. Such an exposure may also enhance the education of a resident. A 17-question electronic survey was developed to quantify the interest of orthopedic residents in pursuing an elective international rotation. The survey, which gathered resident demographic data and interest in pursuing an elective international orthopedic rotation, was sent to (and completed by) all 38 University of Washington orthopedic residents during academic year 2007-2008. More than 60% (23/38) of residents indicated they would be willing to commit to an international rotation; an additional 24% (9/38) indicated they would be very interested. Almost 40% of residents had participated in international medical volunteerism before entering residency. Among residents, there is a clear interest in pursuing an international rotation to complement their education in the United States.

Biomechanical comparison of lumbosacral fixation techniques in a calf spine model.

STUDY DESIGN: biomechanical testing of the strength and stability of lumbosacral fixation constructs. OBJECTIVES: The purpose of this study was to quantify and compare the biomechanical properties of five different lumbosacral fixation constructs and determine the benefit of adding supplementary fixation to S1 screws. SUMMARY OF BACKGROUND DATA: Extension of long fusions to the sacrum remains a difficult clinical challenge. Only a limited number of biomechanical studies have evaluated the different fixation methods available, and none has included both nondestructive and load to failure testing of these fixation methods. METHODS: Six fresh-frozen calf spines were prepared and tested for each construct. The five constructs tested included the following: S1 screws alone, S1 screws and S2 proximally directed screws, S1 screws and S2 distally directed screws, S1 screws and intrasacral rods, and S1 screws and iliac screws. Nondestructive, multidirectional flexibility analyses included four loading methods followed by a destructive flexural load to failure. Lumbosacral peak range of motion (millimeters or degrees) and ultimate failure load (Nm) of the five reconstruction techniques were statistically compared using a one-way analysis of variance combined with a Student-Newman-Keuls post hoc test. RESULTS: S1 screw strain tested in flexion-extension was significantly reduced by the addition of any second point of distal fixation. There was no significant difference between any of the different sacral fixation constructs (P > 0.05). In axial compression, only the addition of iliac screws significantly reduced S1 screw strain. In destructive testing under flexion loading, only iliac screws statistically increased the load at failure (P = 0.005). CONCLUSION: This study demonstrates the effectiveness of adding a second fixation point distal to the S1 screws in reducing S1 screw strain. Iliac fixation is more effective than secondary sacral fixation points but may not be necessary in all clinical situations. Only iliac fixation effectively increased the load to failure under catastrophic loading conditions. Supplementary sacral fixation failed to significantly protect against catastrophic failure. These findings support the clinical observation that iliac fixation is least likely to fail in high-risk, long fusions. Whether testing range of motion, screw strain, or load to failure, no benefit could be demonstrated for intrasacral rod placement when compared with other supplementary sacral fixation techniques. Intrasacral rod placement was equal to a second sacral screw in reducing S1 screw strain during flexion-extension loading. It was not as effective as iliac fixation in reducing screw strain or preventing catastrophic failure. When choosing fixation methods in long fusions to the sacrum, this study supports the use of iliac fixation as the method least likely to loosen or pull out. A second point of sacral fixation also offers biomechanical advantages when compared with S1 fixation alone and may be an appropriate choice in less "high risk" fusions to the sacrum.