OBJECTIVE: Economic access to costly medications including biologic agents can be challenging. Our objective was to examine whether patients with rheumatoid arthritis (RA) are at particular risk for cost-related medication nonadherence (CRN) and spending less on basic needs.
METHODS: We identified a nationally representative sample of older adults with RA (n = 1100) in the Medicare Current Beneficiary Survey (2004-2008) and compared them to older adults with other morbidities categorized by chronic disease count: 0 (n = 5898), 1-2 (n = 30,538), and >/= 3 (n = 34,837). We compared annual rates of self-reported CRN (skipping or reducing medication doses or not obtaining prescriptions because of cost) as well as spending less on basic needs to afford medications and tested for differences using survey-weighted logistic regression analyses adjusted for demographic characteristics, health status, and prescription drug coverage.
RESULTS: In the RA sample, the unadjusted weighted prevalence of CRN ranged from 20.7% in 2004 to 18.4% in 2008 as compared to 18.5% and 11.9%, respectively, in patients with 3 or more non-RA conditions. In adjusted analyses, having RA was associated with a 3.5-fold increase in the risk of CRN (OR 3.52, 95% CI 2.63-4.71) and almost a 2.5-fold risk of spending less on basic needs (OR 2.41, 95% CI 1.78-3.25) as compared to those without a chronic condition.
CONCLUSION: Patients with RA experience a high prevalence of CRN and forgoing of basic needs, more than do older adults with multiple other chronic conditions. The situation did not improve during a period of policy change aimed at alleviating high drug costs.
PURPOSE: To investigate whether a delay in the timing of surgery of > 6 months compared with performing the surgery 6 months after ACL injury. "New" meniscal tears were defined as lesions detected at the time of surgery that were not detected by MRI.
RESULTS: Of 195 patients who were selected based on inclusion criteria, 171 patients underwent surgery 6 months after their ACL injury. The prevalence of new medial meniscal tears in the early reconstruction group was 4.1%, while in the delayed reconstruction group, the prevalence was 16.7% (P = 0.012).
CONCLUSION: A delay in the timing of ACL reconstruction from 6 months following injury is associated with a significant increase in the prevalence of medial meniscal tears (P = 0.012), with a relative risk of 4.07 (CI, 1.29-12.88).
(alpha-NaYbF4:Tm(3+))/CaF2 core/shell nanoparticles with efficient near-infrared to near-infrared upconversion for high-contrast deep tissue bioimaging
We describe the development of novel and biocompatible core/shell (alpha-NaYbF(4):Tm(3+))/CaF(2) nanoparticles that exhibit highly efficient NIR(in)-NIR(out) upconversion (UC) for high contrast and deep bioimaging. When excited at ~980 nm, these nanoparticles emit photoluminescence (PL) peaked at ~800 nm. The quantum yield of this UC PL under low power density excitation (~0.3 W/cm(2)) is 0.6 +/- 0.1%. This high UC PL efficiency is realized by suppressing surface quenching effects via heteroepitaxial growth of a biocompatible CaF(2) shell, which results in a 35-fold increase in the intensity of UC PL from the core. Small-animal whole-body UC PL imaging with exceptional contrast (signal-to-background ratio of 310) is shown using BALB/c mice intravenously injected with aqueously dispersed nanoparticles (700 pmol/kg). High-contrast UC PL imaging of deep tissues is also demonstrated, using a nanoparticle-loaded synthetic fibrous mesh wrapped around rat femoral bone and a cuvette with nanoparticle aqueous dispersion covered with a 3.2 cm thick animal tissue (pork).
Both positively and negatively charged residues play pivotal roles in recruiting precursor ions or ion clusters, and lowering interfacial energy in natural biomineralization process. Synergistic utilization of opposite charges, however, has rarely been implemented in the design of cytocompatible synthetic scaffolds promoting hydroxyapatite (HA)-mineralization and osteointegration. We report the use of cytocompatible zwitterionic sulfobetaine ligands to enable 3-dimensional in vitro mineralization of HA across covalently crosslinked hydrogels. The overall charge-neutral zwitterionic hydrogel effectively recruited oppositely charged precursor ions while overcame excessive swelling exhibited by anionic and cationic hydrogels under physiological conditions, resulting in denser and structurally well-integrated mineralized composites. Further controls over the size, content, and spatial distribution of the mineral domains within the zwitterionic hydrogel are accomplished by facile adjustments of hydrogel crosslinking densities and the supersaturation rate governing heterogeneous mineral nucleation and growth. These findings should inspire many creative uses of zwitterionic polymers and polymer coatings for skeletal tissue repair and regeneration.
Radiofrequency (RF) neurotomy is an interventional procedure used to alleviate certain types of low back pain. RF energy is used to thermally coagulate the specific nerves that transmit pain signals. Recent evidence has shown that this procedure demonstrates significant efficacy in relieving low back pain in lumbar zygapophysial joints, and research is ongoing to determine if pain relief for the sacroiliac joint is also possible. This article provides an evidence-based background for performing RF neurotomy, discusses the relevant anatomy, and highlights the indications and technique for lumbar and sacral RF neurotomy.
A Delphi Exercise to Identify Characteristic Features of Gout -- Opinions from Patients and Physicians, the First Stage in Developing New Classification Criteria
OBJECTIVE: To identify a comprehensive list of features that might discriminate between gout and other rheumatic musculoskeletal conditions, to be used subsequently for a case-control study to develop and test new classification criteria for gout.
METHODS: Two Delphi exercises were conducted using Web-based questionnaires: one with physicians from several countries who had an interest in gout and one with patients from New Zealand who had gout. Physicians rated a list of potentially discriminating features that were identified by literature review and expert opinion, and patients rated a list of features that they generated themselves. Agreement was defined by the RAND/UCLA disagreement index.
RESULTS: Forty-four experienced physicians and 9 patients responded to all iterations. For physicians, 71 items were identified by literature review and 15 more were suggested by physicians. The physician survey showed agreement for 26 discriminatory features and 15 as not discriminatory. The patients identified 46 features of gout, for which there was agreement on 25 items as being discriminatory and 7 items as not discriminatory.
CONCLUSION: Patients and physicians agreed upon several key features of gout. Physicians emphasized objective findings, imaging, and patterns of symptoms, whereas patients emphasized severity, functional results, and idiographic perception of symptoms.
BACKGROUND: Anti-tumor necrosis factor-alpha (TNF-alpha) agents have been hypothesized to increase the risk of interstitial lung disease (ILD), including its most severe manifestation, pulmonary fibrosis.
METHODS: We conducted a cohort study among autoimmune disease patients who were members of Kaiser Permanente Northern California, 1998-2007. We obtained therapies from pharmacy data and diagnoses of ILD from review of X-ray and computed tomography reports. We compared new users of anti-TNF-alpha agents to new users of non-biologic therapies using Cox proportional hazards analysis to adjust for baseline propensity scores and time-varying use of glucocorticoids. We also made head-to-head comparisons between anti-TNF-alpha agents.
RESULTS: Among the 8417 persons included in the analysis, 38 (0.4%) received a diagnostic code for ILD by the end of follow-up, including 23 of 4200 (0.5%) who used anti-TNF-alpha during study follow-up, and 15 of 5423 (0.3%) who used only non-biologic therapies. The age-standardized and gender-standardized incidence rate of ILD, per 100 person-years, was 0.21 [95% confidence interval (CI) 0-0.43] for rheumatoid arthritis and appreciably lower for other autoimmune diseases. Compared with the use of non-biologic therapies, use of anti-TNF-alpha therapy was not associated with a diagnosis of ILD among patients with rheumatoid arthritis (adjusted hazard ratio, 1.03; 95%CI 0.51-2.07), nor did head-to-head comparisons across anti-TNF-alpha agents suggest important differences in risk, although the number of cases available for analysis was limited.
CONCLUSION: The study provides evidence that compared with non-biologic therapies, anti-TNF-alpha therapy does not increase the occurrence of ILD among patients with autoimmune diseases and informs research design of future safety studies of ILD. Copyright (c) 2013 John Wiley and Sons, Ltd.
The Institute of Medicine defines disparity as the difference in health care utilization or outcome not including patient preference.(1) This definition of health disparity holds true in most cases but not all. Total joint replacement (TJR) in the management of knee and hip osteoarthritis (OA) might represent an exception to the rule. TJR, and more specifically knee and hip elective TJR, is considered to be one of the most successful treatments in the history of surgery. Today more than 700 000 TJRs are performed each year in the United States. (Am J Public Health. Published online ahead of print February 14, 2013: e1-e2. doi:10.2105/AJPH.2012.301077).
The incidence of C5 palsy after multilevel cervical decompression procedures: a review of 750 consecutive cases
STUDY DESIGN: Retrospective review of 750 consecutive multilevel cervical spine decompression surgeries performed by a single spine surgeon.
OBJECTIVE: To determine the incidence of C5 palsy in a large consecutive series of multilevel cervical spine decompression procedures.
SUMMARY OF BACKGROUND DATA: Palsy of the C5 nerve is a well-known potential complication of cervical spine surgery with reported rates ranging from 0% to 30%. The etiology remains uncertain but has been attributed to iatrogenic injury during surgery, tethering from shifting of the spinal cord, spinal cord ischemia, and reperfusion injury of the spinal cord.
METHODS: We included patients undergoing multilevel cervical corpectomy, corpectomy with posterior fusion, posterior laminectomy and fusion, and laminoplasty. Exclusion criteria included lack of follow-up data, spinal cord injury preventing preoperative or postoperative motor testing, or surgery not involving the C5 level. Incidence of C5 palsy was determined and compared to determine whether significant differences existed among the various procedures, patient age, sex, revision surgery, preoperative weakness, diabetes, smoking, number of levels decompressed, and history of previous upper extremity surgery.
RESULTS: Of the 750 patients, 120 were eliminated on the basis of the exclusion criteria. The 630 patients included in the analysis consisted of 292 females and 338 males. The mean age was 58 years (range, 19-87). The incidence of C5 nerve palsy for the entire group was 42 of 630 (6.7%). The incidence was highest for the laminectomy and fusion group (9.5%), followed by the corpectomy with posterior fusion group (8.4%), the corpectomy group (5.1%), and finally the laminoplasty group (4.8%), although these differences did not reach statistical significance. There was a significantly higher incidence in males (8.6% vs. 4.5%, P = 0.05).
CONCLUSION: Incidence of C5 nerve palsy after cervical spine decompression was 6.7%. This is consistent with previously published studies and represents the largest series of North American patients to date. There is no statistically significant difference in incidence of C5 palsy based on surgical procedure, although there was a trend toward higher rates with laminectomy and fusion.
Posterior cervical decompression and fusion can be performed for various spinal conditions. Previous rates of pseudoarthrosis have been reported in up to 38% of patients. The use of bone morphogenic protein (BMP) has been approved for use in certain anterior lumbar interbody fusion techniques to decrease the incidence of pseudoarthrosis. Bone morphogenic protein in the anterior cervical spine carries a potential increased risk of airway complications; however, few data exist on the safety and efficacy of BMP in the posterior cervical spine. The purpose of this study was to evaluate fusion success, safety, and heterotopic bone formation using BMP in posterior cervical fusion.Twenty-nine patients who received posterior cervical fusion with BMP were followed for a minimum of 12 months. Computed tomography scans were obtained at a minimum of 12 months postoperatively to evaluate for solid arthrodesis and the presence of heterotopic bone formation. Patients' demographic data and adverse events were evaluated. All patients underwent posterior cervical decompression and instrumented fusion of at least 1 level between 2006 and 2008. Of 37 patients eligible for the study, 29 agreed to participate. Three (10.3%) of 29 patients developed pseudoarthrosis, as found on computed tomography scan. None of these went on to further surgery. No evidence existed of heterotopic bone formation outside of the lateral masses or bone growth over the spinal canal or neuroforamen. No adverse events were related to the use of BMP in this series of posterior cervical fusions. Bone morphogenic protein can be used safely in posterior cervical spine fusion, but additional larger studies are recommended. Even with the use of bone morphogenic protein, the possibility of pseudoarthrosis exists.
The incidence of pedicle screw breech varies based on anatomic location, body habitus, surgeon experience, spinal deformity, and surgical technique. Pedicle breeches have been reported to occur in up to 40% of screws. The purpose of this retrospective study was to compare the rates of revision of pedicle screw placement when using intraoperative C-arm vs O-arm (Medtronic, Memphis, Tennessee) assessment of pedicle screws. An economic analysis was also performed based on the estimated cost of pedicle screw revision. Four (1%) of 386 control patients required pedicle screw revision for a breeched pedicle screw not identified with intraoperative C-arm fluoroscopy. In the study group, none of the 331 patients returned to the operating room when O-arm was used to assess pedicle screw placement. Based on the 1% rate of returning to the operating room in the control group, the annual rate of cases nationwide requiring pedicle screw revision would be approximately 2300, with a cost of approximately $40,595,000.These results suggest that the use of intraoperative O-arm can reduce the need for revision of a breeched pedicle screw. This can potentially lead to a major cost savings.
Postoperative infection treatment score for the spine (PITSS): construction and validation of a predictive model to define need for single versus multiple irrigation and debridement for spinal surgical site infection
BACKGROUND CONTEXT: There is very little evidence to guide treatment of patients with spinal surgical site infection (SSI) who require irrigation and debridement (I&D) in deciding need for single or multiple I&Ds or more complex wound management such as vacuum-assisted closure dressing or soft-tissue flaps.
PURPOSE: The purpose of this study was to build a predictive model that stratifies patients with spinal SSI, allowing us to determine which patients will need single versus multiple I&D. The model will be validated and will serve as evidence to support a scoring system to guide treatment.
STUDY DESIGN: A consecutive series of 128 patients from a tertiary spine center (collected from 1999 to 2005) who required I&D for spinal SSI were studied based on data from a prospectively collected outcomes database.
METHODS: More than 30 variables were identified by extensive literature review as possible risk factors for SSI and tested as possible predictors of risk for multiple I&D. Logistic regression was conducted to assess each variable's predictability by a "bootstrap" statistical method. A prediction model was built in which single or multiple I&D was treated as the "response" and risk factors as "predictors." Next, a second series of 34 different patients meeting the same criteria as the first population were studied. External validation of the predictive model was performed by applying the model to the second data set, and predicted probabilities were generated for each patient. Receiver operating characteristic curves were constructed, and the area under the curve (AUC) was calculated.
RESULTS: Twenty-four of one hundred twenty-eight patients with spinal SSI required multiple IandD. Six predictors: anatomical location, medical comorbidities, specific microbiology of the SSI, the presence of distant site infection (ie, urinary tract infection or bacteremia), the presence of instrumentation, and the bone graft type proved to be the most reliable predictors of need for multiple I&D. Internal validation of the predictive model yielded an AUC of 0.84. External validation analysis yielded AUC of 0.70 and 95% confidence interval of 0.51 to 0.89. By setting a probability cutoff of .24, the negative predictive value (NPV) for multiple I&D was 0.77 and positive predictive value (PPV) was 0.57. A probability cutoff of .53 yielded a PPV of 0.85 and NPV of 0.46.
CONCLUSIONS: Patients with positive methicillin-resistant Staphylococcus aureus culture or those with distant site infection such as bacteremia were strong predictors of need for multiple I&D. Presence of instrumentation, location of surgery in the posterior lumbar spine, and use of nonautograft bone graft material predicted multiple I&D. Diabetes also proved to be the most significant medical comorbidity for multiple I&D. The validation of this predictive model revealed excellent PPV and good NPV with appropriately chosen probability cutoff points. This study forms the basis for an evidence-based classification system, the Postoperative Infection Treatment Score for the Spine that stratifies patients who require surgery for SSI, based on specific spine, patient, infection, and surgical factors to assess a low, indeterminate, and high risk for the need for multiple I&D.
OBJECT: The nature of physician-industry conflict of interest (COI) has become a source of considerable concern, but is often not discussed in the research setting. With reduced funding available from government and nonprofit sources, industry support has enthusiastically grown, but along with this comes the potential for COI that must be regulated. In this era of shared decision making in health care, society must have input into this regulation. The purpose of this study was to assess the opinions of a North American population sample on COI regarding industry-funded research and to analyze population subgroups for trends.
METHODS: A survey was developed for face and content validity, underwent focus group evaluation for clarity and bias reduction, and was administered via the World Wide Web. Demographic and general survey results were summarized as a percentage for each answer, and subgroup analysis was done using logistic regression. Generalizability of the sample to the US population was also assessed.
RESULTS: Of 541 surveys, 40 were excluded due to missing information, leaving 501 surveys for analysis. The sample population was composed of more females, was older, and was more educated than a representative cross-section of the American population. Respondents support multidisciplinary surgeon-industry COI regulation and trust doctors and their professional societies the most to head this effort. Respondents trust government officials and company representatives the least with respect to regulation of COI. Most respondents feel that industry-sponsored research can involve physiciansand be both objective and beneficial to patients.
CONCLUSIONS: Most respondents in this study felt that surgeons should be involved in industry-sponsored research and that more research, regardless of funding source, will ultimately benefit patients. The majority of respondents distrust government or industry to regulate COI. The development of evidence-based treatment recommendations requires the inclusion of patient preference. The authors encourage regulatory bodies to follow suit and include society's perspective on regulation of COI in research.
An evidence-based medicine process to determine outcomes after cervical spine trauma: what surgeons should be telling their patients
STUDY DESIGN: A systematic review of the available medical literature from 1980 to 2010 was conducted and combined with expert opinion from a recent survey of experts regarding cervical spine fractures. Using an objective, hierarchical approach, the best available evidence is presented for health-related quality-of-life outcomes for these injuries.
OBJECTIVE: To provide an evidence-based set of guidelines for cervical spine injuries in order to reduce variability in the information given to patients and their families.
SUMMARY OF BACKGROUND DATA: Patients' expectations regarding quality-of-life outcomes are highly dependent on the information provided by surgeons early in the treatment course. Our previous work has demonstrated that there is substantial variability in what surgeons tell patients regarding outcomes of cervical spine injuries, thus patients' expectations will differ and outcomes vary.
METHODS: Four common cervical spine injuries (C1 burst, Hangman fracture, odontoid fracture, and unilateral facet fracture) treated both surgically and nonsurgically were considered. We assessed the evidence regarding 5 health-related quality-of-life outcomes: time to return to work, activity level, hospital stay, the proportion of patients who are pain free and patients who have regained full range of motion at 1 year after the injury.
RESULTS: Published outcome data were available for most injuries. Using consensus expert opinion and the literature, answers to each question were achieved. Overall, expert opinion was relatively homogeneous across injury types, suggesting that experts do not distinguish between specific injuries when advising patients of expected outcomes such as pain.
CONCLUSION: By overcoming gaps in the literature with consensus expert opinion, our study provides surgeons and others with evidence-based medicine guidelines for patient-centered outcomes after cervical spine injury. This information can be presented to patients to frame expectations of typical outcomes during and after treatment to optimize patient care and quality of life.
Unicameral bone cysts are rare in adults and are most often found incidentally on radiographs. However, they can persist from the adolescent period and may be present in locations that predispose to or exacerbate fractures.This article describes a case of a healthy 40-year-old woman who sustained a proximal humerus trauma that involved a large unicameral bone cyst, resulting in a 3-part head-splitting fracture. The epiphyseal location of the cyst contributed to the severity and extent of the fracture that resulted from a simple fall. Given the age of the patient, open reduction and internal fixation with a locking plate and lag screws was performed. The patient chose open reduction and internal fixation to preserve a hemiarthroplasty procedure in case of future revision. Successful humeral head reconstruction was achieved, and the patient fully recovered. One year postoperatively, the patient underwent arthroscopic debridement to alleviate subjective stiffness and decreased range of motion.Multipart head-splitting fractures require complex repair strategies. The gold standard for the treatment of these injuries is hemiarthroplasty. However, the decision process is difficult in a young patient given the average survival of autoplastic prostheses and the added difficulty of later revision. The current case demonstrates the complexity of decision making resulting from a rare injury in a young, healthy patient and shows that open reduction and internal fixation can provide acceptable reconstruction in such situations.
Does intraoperative neurophysiological monitoring have predictive value for functional recovery following spinal cord injury? A case report
To present a case report of a patient with an ASIA B spinal cord injury with partially intact baseline IONM who made a complete functional recovery postoperatively. A thirty-three year old male presented after a motor vehicle accident. Imaging studies revealed a C4-C5 bilateral facet dislocation. On presentation the patient had 4/5 strength in bilateral biceps and wrist extensors, 3/5 strength in bilateral triceps, and 0/5 strength in the finger flexors, intrinsics and all lower extremity muscles. Motor level was C7. Sensation was grossly intact to light touch throughout all extremities, intact to pinprick from C2 to T7, and absent to pinprick caudal to T7. Rectal tone and contraction were absent. After attempts at closed reduction failed the patient underwent an open reduction and posterior C4-C5 fusion. Intraoperative neurophysiologic monitoring (IONM) revealed the presence of baseline responses to the posterior tibial nerve using somatosensory evoked potentials and to the right abductor hallucis using transcranial motor evoked potentials. At the 6 weeks postoperative visit the patient had full 5/5 motor strength to all muscles except the left deltoid that was 4/5 due to a rotator cuff injury. This case illustrates a potential prognostic value of IONM. Despite lack of clinical motor function at the time of surgery, IONM was able to illicit a motor response in the right lower extremity. Further prospective studies are needed for further investigation.
BACKGROUND: C5 nerve palsy is a known complication of cervical spine surgery. The development and etiology of this complication are not completely understood. The purpose of the present study was to determine whether rotation of the cervical spinal cord predicts the development of a C5 palsy.
METHODS: We performed a retrospective review of prospectively collected spine registry data as well as magnetic resonance images. We reviewed the records for 176 patients with degenerative disorders of the cervical spine who underwent anterior cervical decompression or corpectomy within the C4 to C6 levels. Our measurements included area for the spinal cord, space available for the cord, and rotation of the cord with respect to the vertebral body.
RESULTS: There was a 6.8% prevalence of postoperative C5 nerve palsy as defined by deltoid motor strength of /= 11 degrees ) and palsy (point-biserial correlation = 0.94; p < 0.001). A diagnostic criterion of 6 degrees of rotation could identify patients who had a C5 palsy (sensitivity = 1.00 [95% confidence interval, 0.70 to 1.00], specificity = 0.97 [95% confidence interval, 0.93 to 0.99], positive predictive value = 0.71 [95% confidence interval, 0.44 to 0.89], negative predictive value = 1.00 [95% confidence interval, 0.97 to 1.00]).
CONCLUSIONS: Our evidence suggests that spinal cord rotation is a strong and significant predictor of C5 palsy postoperatively. Patients can be classified into three types, with Type 1 representing mild rotation (0 degrees to 5 degrees ), Type 2 representing moderate rotation (6 degrees to 10 degrees ), and Type 3 representing severe rotation (>/= 11 degrees ). The rate of C5 palsy was zero of 159 in the Type-1 group, eight of thirteen in the Type-2 group, and four of four in the Type-3 group. This information may be valuable for surgeons and patients considering anterior surgery in the C4 to C6 levels.
Estimating the effective radiation dose imparted to patients by intraoperative cone-beam computed tomography in thoracolumbar spinal surgery
STUDY DESIGN: Observational.
OBJECTIVE: To estimate the radiation dose imparted to patients during typical thoracolumbar spinal surgical scenarios.
SUMMARY OF BACKGROUND DATA: Minimally invasive techniques continue to become more common in spine surgery. Computer-assisted navigation systems coupled with intraoperative cone-beam computed tomography (CT) represent one such method used to aid in instrumented spinal procedures. Some studies indicate that cone-beam CT technology delivers a relatively low dose of radiation to patients compared with other x-ray-based imaging modalities. The goal of this study was to estimate the radiation exposure to the patient imparted during typical posterior thoracolumbar instrumented spinal procedures, using intraoperative cone-beam CT and to place these values in the context of standard CT doses.
METHODS: Cone-beam CT scans were obtained using Medtronic O-arm (Medtronic, Minneapolis, MN). Thermoluminescence dosimeters were placed in a linear array on a foam-plastic thoracolumbar spine model centered above the radiation source for O-arm presets of lumbar scans for small or large patients. In-air dosimeter measurements were converted to skin surface measurements, using published conversion factors. Dose-length product was calculated from these values. Effective dose was estimated using published effective dose to dose-length product conversion factors.
RESULTS: Calculated dosages for many full-length procedures using the small-patient setting fell within the range of published effective doses of abdominal CT scans (1-31 mSv). Calculated dosages for many full-length procedures using the large-patient setting fell within the range of published effective doses of abdominal CT scans when the number of scans did not exceed 3.
CONCLUSION: We have demonstrated that single cone-beam CT scans and most full-length posterior instrumented spinal procedures using O-arm in standard mode would likely impart a radiation dose within the range of those imparted by a single standard CT scan of the abdomen. Radiation dose increases with patient size, and the radiation dose received by larger patients as a result of more than 3 O-arm scans in standard mode may exceed the dose received during standard CT of the abdomen. Understanding radiation imparted to patients by cone-beam CT is important for assessing risks and benefits of this technology, especially when spinal surgical procedures require multiple intraoperative scans.
Serial Transplantation of Bone Marrow to Test Self-renewal Capacity of Hematopoietic Stem Cells In Vivo
Hematopoietic stem cells (HSCs) have the ability to self-renew and replenish the blood and immune system for the life span of an individual. An age-associated decline in HSC function is responsible for the decreased immune function and increased incidence of myeloid diseases and anemia in the elderly. The changes in HSC function are thought to occur as the result of an intrinsic defect in the self-renewal potential of HSCs as they age. In this chapter, we describe a bone marrow serial transplantation protocol designed to test the self-renewal capacity of HSCs in vivo.