Selecting Image-Guided Surgical Technologies in Oncology: A Surgeon's Perspective.

BACKGROUND: To improve surgical performance, image-guided (IG) technologies are increasingly introduced. Yet, it is unknown which oncological procedures yield most value from these technologies. This study aimed to select the most promising IG technology per oncologic indication. METHODS: An Analytic Hierarchical Process was used to evaluate three IG technologies: navigation, optical imaging, and augmented reality, in five oncologic indications compared with usual care. Sixteen decision criteria were selected. The relative importance of the criteria and the expected performance of the technologies were evaluated among surgeons. The combination of these scores gives the expected value per technology. RESULTS: On criteria level, sparing critical tissue (9%-18%) and reducing the risk of local recurrence (11%-27%) were most important. Navigation was preferred in three indications-removal of lymph nodes (42%), liver (47%), and rectal tumors (33%). In removing rectal tumors, optical imaging was equally preferred (34%). In removing breast and tongue tumors, no technology was clearly preferred. CONCLUSIONS: In selecting IG technologies, especially optical and navigation technologies are expected to add value in addition to usual care. Further development of those technologies for the preferred indications seems valuable. Multi-attribute analysis showed to be useful in prioritization of conducting clinical studies and steer research and development initiatives.

Health Care Utilization and Payer Cost Analysis of Robotic Arm Assisted Total Knee Arthroplasty at 30, 60, and 90 Days.

This study performed a health care utilization analysis between robotic arm assisted total knee arthroplasty (rTKA) and manual total knee arthroplasty (mTKA) techniques. Specifically, we compared (1) index costs and (2) discharge dispositions, as well as (3) 30-day (4) 60-day, and (5) 90-day (a) episode-of-care costs, (b) postoperative health care utilization, and (c) readmissions. The 100% Medicare Standard Analytical Files were used for rTKAs and mTKAs performed between January 1, 2016, and March 31, 2017. Based on strict inclusion-exclusion criteria and 1:5 propensity score matching, 519 rTKA and 2,595 mTKA patients were analyzed. Total episode payments, health care utilization, and readmissions, at 30-, 60-, and 90-day time points were compared using generalized linear model, binomial regression, log link, Mann-Whitney, and Pearson's chi-square tests. The rTKA versus mTKA cohort average total episode payment was US$17,768 versus US$19,899 (p < 0.0001) at 30 days, US$18,174 versus US$20,492 (p < 0.0001) at 60 days, and US$18,568 versus US$20,960 (p < 0.0001) at 90 days. At 30 days, 47% fewer rTKA patients utilized skilled nursing facility (SNF) services (13.5 vs. 25.4%; p < 0.0001) and had lower SNF costs at 30 days (US$6,416 vs. US$7,732; p = 0.0040), 60 days (US$6,678 vs. US$7,901, p = 0.0072), and 90 days (US$7,201 vs. US$7,947, p = 0.0230). rTKA patients also utilized fewer home health visits and costs at each time point (p < 0.05). Additionally, 31.3% fewer rTKA patients utilized emergency room services at 30 days postoperatively and had 90-day readmissions (5.20 vs. 7.75%; p = 0.0423). rTKA is associated with lower 30-, 60-, and 90-day postoperative costs and health care utilization. These results are of marked importance given the emphasis to contain and reduce health care costs and provide initial economic insights into rTKA with promising results.

Efficacy and Safety of Atlantoaxial Fluoroscopy-guided Pedicle Screw Fixation in Patients Younger Than 12 Years: A Radiographic and Clinical Assessment.

STUDY DESIGN: A retrospective clinical study. OBJECTIVE: The aim of this study was to evaluate the efficacy and safety of fluoroscopy-guided atlantoaxial pedicle screw fixation in patients younger than 12 years. SUMMARY OF BACKGROUND DATA: C1-C2 pedicle screw fixation is a widely accepted treatment method for atlantoaxial dislocation (AAD). However, data regarding its use for atlantoaxial fusion (AAF) in children are limited. METHODS: Thirty-six consecutive patients younger than 12 years underwent C1-C2 pedicle screw fixation for AAD between 2007 and 2017. Anatomical parameters of the C1 pedicle were measured on preoperative computed tomography (CT). Accuracy of pedicle screw fixation was assessed on postoperative CT using the following definitions: Type I, screw threads completely within the bone; Type II, less than half the diameter of the screw violating the surrounding cortex; and Type III, clear violation of the transverse foramen or spinal canal. Demographic, surgical, radiation dose, and clinical data were recorded. RESULTS: Patients underwent 144 screw fixations (67 C1 pedicle screws, 68 C2 pedicle screws, 5 C1 lateral mass screws, and 4 C-2 laminar screws) for a variety of pediatric AADs, with 36.5 ±â€Š8.5 months of follow-up. Among the 135 pedicle screws, 96.3% were deemed "safe" (Type I or II) and 80.7% (109/135) of the screws were rated as being ideal (Type I); five screws (3.7%) were identified as unacceptable (Type III). Average estimated blood loss (EBL) was 92 mL, and the average total radiation exposure during the operation was 6.2 mGy (in the final 26 cases). There were no neurovascular injuries. All patients showed radiographic stability and symptom resolution. CONCLUSION: C1-C2 pedicle screw fixation under fluoroscopy is safe and effective for the treatment of AAD in children younger than 12 years. However, it may be technically challenging owing to the special anatomical features of children and should be performed by experienced surgeons. LEVEL OF EVIDENCE: 3.

Comparative Effectiveness of Uterine Leiomyoma Procedures Using a Large Insurance Claims Database.

OBJECTIVE: To compare risk of reintervention, long-term clinical outcomes, and health care utilization among women who have bulk symptoms from leiomyoma and who underwent the following procedures: hysterectomy, myomectomy, uterine artery embolization, and magnetic resonance-guided, focused ultrasound surgery. METHODS: This was a retrospective analysis of administrative claims from a large U.S. commercial insurance database. Women aged 18-54 years undergoing any of the previously mentioned leiomyoma procedures between 2000 and 2013 were included. We assessed the following outcome measures: risk of reintervention between uterine-sparing procedures, risk of other surgical procedures or complications of the index procedure, 5-year health care utilization, pregnancy rates, and reproductive outcomes. Propensity score matching along with Cox proportional hazard models were used to adjust for differences in baseline characteristics between study cohorts. RESULTS: Among the 135,522 study-eligible women with mean follow-up of 3.4 years, hysterectomy was the most common first-line procedural therapy (111,324 [82.2%]) followed by myomectomy (19,965 [14.7%]), uterine artery embolization (4,186 [3.1%]) and magnetic resonance-guided focused ultrasound surgery (47 [0.0003%]). Small but statistically significant differences were noted for uterine artery embolization and myomectomy in reintervention rate (17.1% compared with 15.0%, P=.02), subsequent hysterectomy rates (13.2% compared with 11.1%, P<.01) and subsequent complications from index procedures (18.1% compared with 24.6%, P<.001). During follow-up, women undergoing myomectomy had lower leiomyoma-related health care utilization, but had higher all-cause outpatient services. Pregnancy rates were 7.5% and 2.2% among myomectomy and uterine artery embolization cohorts, respectively (P<.001) with both cohorts having similar rates of adverse reproductive outcome (69.4%). CONCLUSIONS: Although the overwhelming majority of women having leiomyoma with bulk symptoms underwent hysterectomy as their first treatment procedure, among those undergoing uterine-sparing index procedures, approximately one seventh had a reintervention, and one tenth ended up undergoing hysterectomy during follow-up. Compared with women undergoing myomectomy, women undergoing uterine artery embolization had a higher risk of reintervention, lower risk of subsequent complications, but similar rate of adverse reproductive outcomes.

Accuracy of a new intraoperative cone beam CT imaging technique (Artis zeego II) compared to postoperative CT scan for assessment of pedicle screws placement and breaches detection.

PURPOSE: The goal of this study was to compare the accuracy of a novel intraoperative cone beam computed tomography (CBCT) imaging technique with that of conventional computed tomography (CT) scans for assessment of pedicle screw placement and breach detection. METHODS: Three hundred and forty-eight pedicle screws were inserted in 58 patients between October 2013 and March 2016. All patients had an intraoperative CBCT scan and a conventional CT scan to verify the placement of the screws. The CBCT and CT images were reviewed by two surgeons to assess the accuracy of screw placement and detect pedicle breaches using two established classification systems. Agreement on screw placement between intraoperative CBCT and postoperative CT was assessed using Kappa and Gwet's coefficients. Using CT scanning as the gold standard, the sensitivity, specificity, positive predictive value, and negative predictive value were calculated to determine the ability of CBCT imaging to accurately evaluate screw placement. RESULTS: The Kappa coefficient was 0.78 using the Gertzbein classification and 0.80 using the Heary classification, indicating a substantial agreement between the intraoperative CBCT and postoperative CT images. Gwet's coefficient was 0.94 for both classifications, indicating almost perfect agreement. The sensitivity, specificity, positive predictive value and negative predictive value of the CBCT images were 77, 98, 86, and 96%, respectively, for the Gertzbein classification and 79, 98, 88, and 96%, respectively, for the Heary classification. CONCLUSIONS: Intraoperative CBCT provides accurate assessment of pedicle screw placement and enables intraoperative repositioning of misplaced screws. This technique may make postoperative CT imaging unnecessary.

Assessing Bone Type of Implant Recipient Sites by Stereomicroscopic Observation of Bone Core Specimens: A Comparison With the Assessment Using Dental Radiography.

BACKGROUND: The aim of the study is to determine if bone quality evaluation of surgically obtained bone core specimens using a stereomicroscope is reliable for determining bone quality at implant recipient sites. METHODS: Bone quality was presurgically assessed in 122 edentulous ridges obtained from 62 patients using periapical radiographs and categorized according to the Lekholm and Zarb classification. During surgery, bone specimens were trephined, and bone types were immediately classified using a stereomicroscope. Microarchitectural characteristics of bone cores were evaluated after being scanned using microcomputed tomography (micro-CT). RESULTS: Bone types of implant sites categorized from radiography and stereomicroscope had statistically similar distribution but poor interrater agreement. Using micro-CT, maxillae and mandibles showed significant differences in microarchitectural characteristics of bone cores. Bone volume (BV), total volume (TV), and trabecular thickness (Tb.Th) increased, whereas bone surface density (BS/BV) and open porosity (Po.[Op]) decreased in mandibular bone cores compared with those in maxillary bone cores. Moreover, micro-CT values of BV/TV and Po.(Op) statistically correlated with bone types assessed by stereomicroscopy, particularly in mandibles (adjusted means of BV/TV of Type 2 to 4 versus Type 1 decreasing from -9.88%, -15.09%, -29.31%; those of Po.(Op) ranged from 9.77%, 15.06%, 29.52% in an upward trend). However, such correlations were not found in maxillae or when bone types were classified using periapical radiographs. CONCLUSIONS: Caution is needed when using presurgical periapical radiographs to predict bone quality at implant recipient sites. Surgically preserved bone core specimens, whenever obtainable, might offer additional information to accurately assess bone quality, particularly at mandibular implant sites.

The development and error analysis of a kinematic parameters based spatial positioning method for an orthopedic navigation robot system.

BACKGROUND: Spatial positioning is the key function of a surgical navigation robot system, and accuracy is the most important performance index of such a system. METHODS: The kinematic parameters of a six degrees of freedom (DOF) robot arm were used to form the transformation from intraoperative fluoroscopy images to a robot's coordinate system without C-arm calibration and to solve the redundant DOF problem. The influences of three typical error sources and their combination on the final navigation error were investigated through Monte Carlo simulation. RESULTS: The navigation error of the proposed method is less than 0.6 mm, and the feasibility was verified through cadaver experiments. Error analysis suggests that the robot kinematic error has a linear relationship with final navigation error, while the image error and gauge error have nonlinear influences. CONCLUSIONS: This kinematic parameters based method can provide accurate and convenient navigation for orthopedic surgeries. The result of error analysis will help error design and assignment for surgical robots.

Computer-Navigated Total Knee Arthroplasty Utilization.

Computer-navigated total knee arthroplasty (CN-TKA) has been used to improve component alignment, though the evidence is currently mixed on whether there are clinically significant differences in long-term outcomes. Given the established increased costs and operative time, we hypothesized that the utilization rate of CN-TKA would be decreasing relative to standard TKA in the Medicare population given the current health care economic environment. We queried 1,914,514 primary TKAs performed in the entire Medicare database from 2005 to 2012. Current Procedural Terminology (CPT) and International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) codes were used to identify and separate CN-TKAs. Utilization of TKA was compared by year, gender, and region. Average change in cases per year and compound annual growth rate (CAGR) were used to evaluate trends in utilization of the procedure. We identified 30,773 CN-TKAs performed over this time period. There was an increase in utilization of CN-TKA per year from 984 to 5,352 (average = 572/year, R (2) = 0.85, CAGR = 23.58%) from 2005 to 2012. In contrast, there was a slight decrease in overall TKA utilization from 264,345 to 230,654 (average = 4297/year, R (2) = 0.74, CAGR = - 1.69%). When comparing proportion of CN-TKA to all TKAs, there was an increase from 0.37 to 2.32% (average 0.26%/year, R (2) = 0.88, CAGR = 25.70%). CN-TKA growth in males and females was comparable at 24.42 and 23.11%, respectively. The South region had the highest growth rate at 28.76%, whereas the Midwest had the lowest growth rate at 15.51%. The Midwest was the only region that peaked (2008) with a slow decline in utilization until 2012. Despite increased costs with unclear clinical benefit, CN-TKA is increasing in utilization among Medicare patients. Reasons could include patient preference, advertising, proper of coding the procedure, and increased publicly available information about arthroplasty options.

[Interest of non invasive navigation in total knee arthroplasty]. / Intérêt de la navigation non invasive dans l'arthroplastie totale de genou.

During surgery of total knee arthroplasty, we use a computerized non invasive navigation (Brainlab Victor Vision CT-free) to assess the accuracy of the bone cuts (navigation expresse). The purpose of this study is to evaluate non invasive navigation when a total knee arthroplasty is achieved by conventional instrumentation. The study is based on forty total knee arthroplasties. The accuracy of the tibial and distal femoral bone cuts, checked by non invasive navigation, is evaluated prospectively. In our clinical series, we have obtained, with the conventional instrumentation, a correction of the mechanical axis only in 90 % of cases (N = 36). With non invasive navigation, we improved the positioning of implants and obtained in all cases the desired axiometry in the frontal plane. Although operative time is increased by about 15 minutes, the non invasive navigation does not induce intraoperative or immediate postoperative complications. Despite the cost of this technology, we believe that the reliability of the procedure is enhanced by a simple and reproducible technique.

Monte Carlo simulation to analyze the cost-benefit of radioactive seed localization versus wire localization for breast-conserving surgery in fee-for-service health care systems compared with accountable care organizations.

OBJECTIVE: In breast-conserving surgery for nonpalpable breast cancers, surgical reexcision rates are lower with radioactive seed localization (RSL) than wire localization. We evaluated the cost-benefit of switching from wire localization to RSL in two competing payment systems: a fee-for-service (FFS) system and a bundled payment system, which is typical for accountable care organizations. MATERIALS AND METHODS: A Monte Carlo simulation was developed to compare the cost-benefit of RSL and wire localization. Equipment utilization, procedural workflows, and regulatory overhead differentiate the cost between RSL and wire localization. To define a distribution of possible cost scenarios, the simulation randomly varied cost drivers within fixed ranges determined by hospital data, published literature, and expert input. Each scenario was replicated 1000 times using the pseudorandom number generator within Microsoft Excel, and results were analyzed for convergence. RESULTS: In a bundled payment system, RSL reduced total health care cost per patient relative to wire localization by an average of $115, translating into increased facility margin. In an FFS system, RSL reduced total health care cost per patient relative to wire localization by an average of $595 but resulted in decreased facility margin because of fewer surgeries. CONCLUSION: In a bundled payment system, RSL results in a modest reduction of cost per patient over wire localization and slightly increased margin. A fee-for-service system suffers moderate loss of revenue per patient with RSL, largely due to lower reexcision rates. The fee-for-service system creates a significant financial disincentive for providers to use RSL, although it improves clinical outcomes and reduces total health care costs.

[Computer-assisted systems in total knee arthroplasty. Useful aid or only additional costs]. / Computerassistenzsysteme in der Knieendoprothetik. Sinnvolle Hilfsmittel oder nur Mehraufwand.

BACKGROUND: The primary goal of computer-assisted surgery (CAS) in total knee arthroplasty is to increase the accuracy in terms of prosthesis positioning. In theory, this would lead to longer implant survival and a reduction of malpositioning. Thus, a better clinical outcome and lower revision rates would be expected. However, the necessary technical equipment represents significant additional effort and cost factors which are not included in the current diagnosis-related groups (DRG) system. OBJECTIVE: The objective of this article is a critical review of the current literature to examine whether these costs are reasonable by taking the additional benefits of the technology into account. METHODS: This review is based on a selective PubMed search on CAS and navigation in primary total knee arthroplasty. RESULTS: The current evidence base on CAS suggests that at least the primary outcome parameter, the improvement of the radiological alignment, is achieved by the technique. However, the claimed secondary effects are not yet proven. In particular, an improvement of clinical outcome and patient satisfaction has not been demonstrated so far. Furthermore, there is some evidence of increased complication rates by the use of CAS. CONCLUSION: Against this background and with respect to further cost-benefit analyses, the technology has to be reviewed critically. In particular, low-volume units do not seem to benefit from the use of CAS. However, the assessment of long-term effects is still pending.

Regional variation and factors associated with image guidance utilization during endoscopic sinus surgery in the ambulatory setting.

OBJECTIVE: Determine regional variation and factors associated with the use of image guidance (IG) during endoscopic sinus surgery (ESS) in the ambulatory surgery center setting. METHODS: All cases of ESS in 2010 were extracted from the state ambulatory surgery databases for New York, North Carolina, Florida, Iowa, and California. Current Procedural Terminology codes for individual sinusotomies and IG and International Classification of Diseases codes along with insurance and regional data were analyzed to determine factors that were associated with the use of IG during ESS. RESULTS: Among 36 646 ambulatory ESS procedures (mean age 46.0 years; 49.0% female), 6676 cases utilized IG (18.2%). Polyps were present in 27.9% of cases. North Carolina had the highest utilization rate for IG (26.0%), whereas Iowa had the lowest (12.8%). On multivariate analysis, use of IG was associated with state, insurance status, community setting, total ethmoidectomy, frontal sinusotomy, sphenoidotomy, and polyps (all P < .001), but not maxillary antrostomy (P = .197). The highest procedural odds ratio for IG use was noted for total ethmoidectomy (2.07), followed by frontal sinusotomy (1.97) and sphenoidotomy (1.26). CONCLUSION: Although IG is utilized in a relative minority of ESS cases, there is considerable regional variation in use. Factors other than complexity of surgery influence IG utilization as well.

The increasing role of nonradiologists in performing ultrasound-guided invasive procedures.

PURPOSE: Recent proliferation of mobile diagnostic ultrasound (US) units and improved resolution have allowed for widespread use of US by more providers, both for diagnosis and US-guided procedures (USGP). This study aims to document recent trends in utilization for USGP in the Medicare population. METHODS: Source data were obtained from the CMS Physician Supplier Procedure Summary Master Files from 2004 to 2010. Allowed billing claims submitted for USGP were extracted and volume was analyzed by provider type and setting. Compound annual growth rates were calculated. RESULTS: The total utilization rate for all USGP was 2,425 per 100,000 in 2004 and 4,870 in 2010, an increase of 100.8% (+2,445 per 100,000) with a compound annual growth rate of 12.3%. The year 2010 represents the first year that nonradiologists as a group performed more USGP than radiologists, at 922,672 versus 794,497 examinations, respectively. Nonradiologists accounted for 72.2% (599,751 of 830,925) of the USGP volume growth from 2004 to 2010. Most 2010 claims were submitted by radiologists (n = 794,497; 46.3%) and surgeons (n = 332,294; 19.4%). The largest overall volume increases from 2004 to 2010 were observed among radiologists, surgeons, anesthesiologists, rheumatologists, midlevel providers, primary care physicians, nonrheumatologist internal medicine subspecialists, and the aggregate of all other provider types. CONCLUSION: The year 2010 represents the first year that nonradiologists performed more USGP than radiologists. From 2004 to 2010, radiologists and surgeons experienced only modest growth in USGP volume, whereas several other provider types experienced more rapid growth. It is likely that many procedures that were previously performed without US guidance are now being performed with US guidance.

Assessment of left ventricular size and function during cardiac surgery. An intraoperative evaluation of six two-dimensional echocardiographic methods with real time three-dimensional echocardiography as a reference.

Transesophageal echocardiography is recommended to monitor left ventricular (LV) size and function in various operations. Generally, two-dimensional (2D) methods are applied intraoperatively. The aim of this study was to compare the accuracy and feasibility of 6 commonly used 2D methods to assess LV function during surgery. LV function in 120 consecutive patients was evaluated. Real time three-dimensional transesophageal echocardiograpy (3DTEE) served as reference. End-diastolic and end-systolic volumes and ejection fraction (EF) were analyzed with Simpson's method of discs (monoplane [MP] and biplane [BP]), eyeball method, Teichholz' method, and speckle tracking (ST) methods. Furthermore, fractional area change (FAC) and peak systolic pressure rise (dP/dt) were determined. Each 2D method was evaluated regarding correlation and agreement with 3DE, intra- and interobserver variability and the time required for evaluation. Simpson BP showed the strongest correlation and best agreement with 3DE for EF (limits of agreement 3.7 ± 11.6%) and volumes. Simpson MP showed similar agreement with 3DE compared to ST (2.8 ± 14.5% vs. 2.0 ± 15.3% and 3.8 ± 14.4% vs. 1.9 ± 15.6%, respectively). Both the eyeball method and Teichholz' method showed wide limits of agreement (-1.5 ± 18.2% and 5.2 ± 22.1%, respectively). DP/dt did not correlate with 3DE. FAC and ST FAC showed similar agreement. Application of 3DE (429 ± 108 seconds) took the longest time, and the eyeball method took the shortest time (8 ± 5 seconds) for analysis. Simpson BP is the most accurate intraoperative 2D method to evaluate LV function, followed by long-axis MP evaluations. Short-axis views were less accurate but may be suited for monitoring. We do not recommend using dP/dt.

Pancreatic surgery: a multidisciplinary assessment of the value of intraoperative US.

PURPOSE: To assess the value of intraoperative ultrasonography (US) for different types of pancreatic surgery. MATERIALS AND METHODS: An institutional review board-approved, HIPAA-compliant retrospective review with waiver of informed consent was performed to evaluate all cases of pancreatic surgery with intraoperative US or laparoscopic US that occurred at a single institution during a 10-year period. Surgical notes, radiologic images, and clinical data for each surgical procedure and subsequent clinical course were reviewed by pancreatic surgeons and radiologists. Presumptive diagnosis, type of surgical procedure performed, and final pathologic data were recorded. A relative value score was established by consensus and assigned to each case with a grade of 0-3, which indicated the value of the intraoperative or laparoscopic US. The type of operation and pathologic data were compared in each of the value score groups. Categoric variables were compared by using either χ(2) or Fisher exact test. RESULTS: One hundred ninety-three intraoperative or laparoscopic US procedures were performed in 189 patients. Of the patients, there were 102 men and 87 women. The mean age was 57.8 years (range, 18-86 years). Intraoperative or laparoscopic US value scores were as follows: value score 0, 3.6%; value score 1, 11.9%; value score 2, 31.1%; and value score 3, 53.4%. The most common contribution that resulted in a high score (value score 3) was facilitation of technical performance of the surgery (n = 60). High value score was significantly associated with performance of pancreatitis-related surgery (P < .001). The surgical indication that most commonly resulted in a low value score of 0 or 1 was staging of pancreatic cancers. All cases that received a score of 0 occurred in the laparoscopic adenocarcinoma surgical setting (staging or pancreatic biopsy). CONCLUSION: Intraoperative or laparoscopic US can be a valuable procedure in multiple types of surgical procedures that involve the pancreas and shows clear patterns of value in the different types of surgery.

Image-guided sinus surgery: practical and financial experiences from a UK centre 2001-2009.

BACKGROUND: Image guidance surgery is an emerging technology that may allow more efficient treatment of sinus disease. This retrospective study examines National Health Service and military patients who underwent procedures using image guidance surgery during the period 2001-2009. METHODS: Medical records were reviewed in terms of indications for surgery, incidence of major complications and need for revision following image guidance surgery. An attempt was also made to determine the cost-effectiveness of purchasing this navigational system. RESULTS: A total of 132 patients underwent 147 procedures using image guidance surgery over the 8-year period. The indications for surgery ranged from severe nasal polyposis and chronic rhinosinusitis to malignant tumours in the paranasal sinus and skull base region. Average length of follow up was 17.6 months. Four patients had a major complication. Fourteen patients underwent revision surgery. The cost of providing an image guidance surgery service was estimated to be £110,000-120,000 during the study period. The economic model for the subgroup of nineteen military patients (with non-polypoid chronic rhinosinusitis) suggests that use of this technology will reduce overall costs by approximately £70,000 when compared with conventional sinus surgery. CONCLUSION: This study provides some evidence that image-guided sinus surgery is cost effective, safe and may decrease surgical revision rates.

The use of computer-assisted orthopaedic surgery in complex cases of hip and knee arthroplasty: experience from a developing country.

The technology of computer-assisted orthopaedic surgery (CAOS) has been used in many developed countries for the last two decades. Initially, it was thought that CAOS would be the standard in surgical practice, but so far its clinical application has been limited due to the involved cost and complexity. The cost-effectiveness of CAOS techniques has also been questioned. Therefore, it is expected that the application of CAOS in developing countries would be more limited for the same reasons. Herein, the author presents a surgical experience of using different CAOS techniques in Egypt. Computer-assisted templating software was used in complex and neglected cases of hip arthritis and in cases of leg length discrepancy. Navigation techniques were employed in knee arthroplasty in patients with extraarticular deformities. Computer-assisted patient-specific instruments were used for bilateral simultaneous knee arthroplasty in medically unfit patients and in patients with severe articular deformities. Contrary to expectations, the experience proved that CAOS is more useful and possibly cost-effective when used in hip and knee arthroplasty for complex and neglected cases in developing countries.

Dosimetric evaluation of the impacts of different heterogeneity correction algorithms on target doses in stereotactic body radiation therapy for lung tumors.

Heterogeneity correction algorithms can have a large impact on the dose distributions of stereotactic body radiation therapy (SBRT) for lung tumors. Treatment plans of 20 patients who underwent SBRT for lung tumors with the prescribed dose of 48 Gy in four fractions at the isocenter were reviewed retrospectively and recalculated with different heterogeneity correction algorithms: the pencil beam convolution algorithm with a Batho power-law correction (BPL) in Eclipse, the radiological path length algorithm (RPL), and the X-ray Voxel Monte Carlo algorithm (XVMC) in iPlan. The doses at the periphery (minimum dose and D95) of the planning target volume (PTV) were compared using the same monitor units among the three heterogeneity correction algorithms, and the monitor units were compared between two methods of dose prescription, that is, an isocenter dose prescription (IC prescription) and dose-volume based prescription (D95 prescription). Mean values of the dose at the periphery of the PTV were significantly lower with XVMC than with BPL using the same monitor units (P < 0.001). In addition, under IC prescription using BPL, RPL and XVMC, the ratios of mean values of monitor units were 1, 0.959 and 0.986, respectively. Under D95 prescription, they were 1, 0.937 and 1.088, respectively. These observations indicated that the application of XVMC under D95 prescription results in an increase in the actually delivered dose by 8.8% on average compared with the application of BPL. The appropriateness of switching heterogeneity correction algorithms and dose prescription methods should be carefully validated from a clinical viewpoint.

[Handling modern imaging procedures in a high-tech operating room]. / Handling moderner Bildgebung in einem Hightech-Operationssaal.

Operating rooms are the central unit in the hospital network in trauma centers. In this area, high costs but also high revenues are generated. Modern operating theater concepts as an integrated model have been offered by different companies since the early 2000s. Our hypothesis is that integrative concepts for operating rooms, in addition to improved operating room ergonomics, have the potential for measurable time and cost savings. In our clinic, an integrated operating room concept (I-Suite, Stryker, Duisburg) was implemented after analysis of the problems. In addition to the ceiling-mounted arrangement, the system includes an endoscopy unit, a navigation system, and a voice control system. In the first 6 months (9/2005 to 2/2006), 112 procedures were performed in the integrated operating room: 34 total knee arthroplasties, 12 endoscopic spine surgeries, and 66 inpatient arthroscopic procedures (28 shoulder and 38 knee reconstructions). The analysis showed a daily saving of 22-45 min, corresponding to 15-30% of the daily changeover times, calculated to account for potential savings in the internal cost allocation of 225-450 EUR. A commercial operating room concept was evaluated in a pilot phase in terms of hard data, including time and cost factors. Besides the described effects further savings might be achieved through the effective use of voice control and the benefit of the sterile handle on the navigation camera, since waiting times for an additional nurse are minimized. The time of the procedure of intraoperative imaging is also reduced due to the ceiling-mounted concept, as the C-arm can be moved freely in the operating theater without hindering cables. By these measures and ensuing improved efficiency, the initial high costs for the implementation of the system may be cushioned over time.

Assessment of a fictitious domain method for patient-specific biomechanical modelling of press-fit orthopaedic implantation.

In this article, we discuss an application of a fictitious domain method to the numerical simulation of the mechanical process induced by press-fitting cementless femoral implants in total hip replacement surgeries. Here, the primary goal is to demonstrate the feasibility of the method and its advantages over competing numerical methods for a wide range of applications for which the primary input originates from computed tomography-, magnetic resonance imaging- or other regular-grid medical imaging data. For this class of problems, the fictitious domain method is a natural choice, because it avoids the segmentation, surface reconstruction and meshing phases required by unstructured geometry-conforming simulation methods. We consider the implantation of a press-fit femoral artificial prosthesis as a prototype problem for sketching the application path of the methodology. Of concern is the assessment of the robustness and speed of the methodology, for both factors are critical if one were to consider patient-specific modelling. To this end, we report numerical results that exhibit optimal convergence rates and thus shed a favourable light on the approach.