In proximal tibial anterior closing wedge (slope changing) osteotomy lower starting points imply larger bone resection.

BACKGROUND: Anterior closing wedge osteotomy (ACWO) for tibial slope correction is a validated procedure in revision anterior cruciate ligament reconstruction (ACLR). This study aims to determine how different starting points of the osteotomy affect the amount of bone resection in ACWO. HYPOTHESIS: We hypothesized that the lower osteotomy starting points in ACWO imply larger bone resection. PATIENTS AND METHODS: A total 52 patients who underwent ACWO using infra-tuberosity technique in our institution were included in this study. Each of patients was simulated using additional two separate methods (based on osteotomy level: supra- and trans-tuberosity) based on lateral calibrated pre-operative X-rays of the whole tibia according to the post-operative correction angle. The resection height of the closing wedge, which corresponded to the base of the osteotomy, was measured and compared among the three groups. RESULTS: The mean actual pre-operative proximal posterior tibial angle (PPTA) was 75.8 ± 2.0°. Post-operatively, PPTA was 84.0 ± 0.6°, and correction angle was 8.2 ± 2.2°. The mean resection height in the supra-tuberosity group was 7.5 ± 0.2 mm, 8.0 ± 2.1 mm in the trans-tuberosity group, and 9.2 ± 2.1 mm in the infra-tuberosity group. There were significant differences between each approach (p ≦ 0.0001). Resection height was moderate positively correlated with the starting point of osteotomy (r = 0.33, 95%CI: 0.18-0.46, p < 0.0001). CONCLUSION: This study suggests that selecting a distal starting point for the osteotomy in ACWO is directly proportional to the observed increase in bone resection, providing valuable insights for pre-operative planning. These findings are clinically relevant and will aid in preoperatively deciding approach in ACWO. LEVEL OF EVIDENCE: IV; retrospective case-control study.

Erotic cue exposure increases physiological arousal, biases choices toward immediate rewards, and attenuates model-based reinforcement learning.

Computational psychiatry focuses on identifying core cognitive processes that appear altered across distinct psychiatric disorders. Temporal discounting of future rewards and model-based control during reinforcement learning have proven as two promising candidates. Despite its trait-like stability, temporal discounting may be at least partly under contextual control. Highly arousing cues were shown to increase discounting, although evidence to date remains somewhat mixed. Whether model-based reinforcement learning is similarly affected by arousing cues remains unclear. Here, we tested cue-reactivity effects (erotic pictures) on subsequent temporal discounting and model-based reinforcement learning in a within-subjects design in n = 39 healthy heterosexual male participants. Self-reported and physiological arousal (cardiac activity and pupil dilation) were assessed before and during cue exposure. Arousal was increased during exposure of erotic versus neutral cues both on the subjective and autonomic level. Erotic cue exposure increased discounting as reflected by more impatient choices. Hierarchical drift diffusion modeling (DDM) linked increased discounting to a shift in the starting point bias of evidence accumulation toward immediate options. Model-based control during reinforcement learning was reduced following erotic cues according to model-agnostic analysis. Notably, DDM linked this effect to attenuated forgetting rates of unchosen options, leaving the model-based control parameter unchanged. Our findings replicate previous work on cue-reactivity effects in temporal discounting and for the first time show similar effects in model-based reinforcement learning in a heterosexual male sample. This highlights how environmental cues can impact core human decision processes and reveal that comprehensive modeling approaches can yield novel insights in reward-based decision processes.

A lower starting point for the medial cut increases the posterior slope in opening-wedge high tibial osteotomy: a cadaveric study.

PURPOSE: The objective of this study was to evaluate the effects on the posterior tibial slope of different distances from the joint line to start the osteotomy and of varying the placement of the opening wedge in high tibial osteotomy. Starting the osteotomy more distally and an incorrect location for the tibial opening wedge were hypothesized to increase the posterior tibial slope. METHODS: A cadaveric study was conducted using 12 knees divided into two groups based on the distance from the joint line to the start of the osteotomy: 3 and 4 cm. The preintervention posterior tibial slope was measured radiologically. Once the osteotomy was performed, the medial cortex of the tibia was divided into anteromedial, medial, and posteromedial thirds. A 10° opening wedge was sequentially placed in each third, and the effect on the posterior tibial slope was evaluated radiographically. RESULTS: Significant changes were observed only in the 3-cm group (p = 0.02) when the wedge was placed in the anteromedial zone. In contrast, in the 4-cm group, significant differences were observed when the opening wedge was placed at both the medial (p = 0.04) and anteromedial (p = 0.012) zones. CONCLUSION: Correct control of the posterior tibial slope can be achieved by avoiding a low point when beginning the osteotomy and placing the opening wedge in the posteromedial third of the tibia when performing an opening-wedge high tibial osteotomy. LEVEL OF EVIDENCE: Controlled laboratory study.

Kinematic draping simulation optimization of a composite B-pillar geometry using particle swarm optimization.

The present work presents an algorithmic approach to determine the optimal starting point for any complex geometry draping processes. The time-efficient Kinematic Draping Simulation (KDS) is used to assess the drapability of a geometry depending on many different starting points. The optimization problem is then solved by applying Particle Swarm Optimization (PSO). The proposed methodology is applied to and validated with complex geometry and a common part of the automobile industry: the B-Pillar geometry. The results show that the PSO algorithm may improve random search up to 78 times. After several experiments, PSO particles have discrete coordinates and are located at optimum global and local regions most of the time, leading to solutions for complex objective functions. The global solution is such that the starting point is located near the geometrical centre of the B-Pillar. The novelty of the work is evident: it uses optimization for a real engineering application, and it draws pattern-related conclusions for other geometries. Experimental results are shown to be consistent with simulation results.

Native tibia valga: a potential source of varus malreduction during intramedullary tibial nail fixation of tibial shaft fractures.

PURPOSE: To determine the effect of native tibia valga on intramedullary nail (IMN) fixation of tibial shaft fractures. METHODS: Retrospective comparative cohort analysis of 110 consecutive patients with tibial shaft fractures undergoing IMN fixation at an urban level one trauma centre was performed. Medical records and radiographs were reviewed for demographics, tibia centre of rotation of angulation (CORA), nail starting point, incidence of varus malreduction, and nail/canal proportional fit. RESULTS: Tibia valga (CORA of ≥ 3 degrees) was present in 37 (33.6%) patients. The anatomic nail starting point distance (in relation to the lateral tibial spine) was significantly greater in the tibia valga group (12.0 mm vs. 5.0 mm, mean difference: 7.1 mm, 95% CI: 5.8 to 8.3 mm, p < 0.0001). Varus malreduction was more common in the tibia valga group (10.8% vs. 1.4%, proportional difference: 9.4%, 95% CI: - 1.0 to 21.3%, p = 0.04). Varus malreduction in the tibia valga group was associated with a decreased nail width/inner canal width proportion on multivariate analysis (OR = 0.683, 95% CI: 0.468 to 0.995, p = 0.0004). CONCLUSION: Native tibia valga is common, and the use of a standard coronal IMN starting point with poor nail fit can lead to iatrogenic varus malreduction. In patients with tibia valga, maximizing nail fit or utilization of a medial starting point should be considered.

Challenges in the target volume definition of lung cancer radiotherapy.

Radiotherapy, with or without systemic treatment has an important role in the management of lung cancer. In order to deliver the treatment accurately, the clinician must precisely outline the gross tumour volume (GTV), mostly on computed tomography (CT) images. However, due to the limited contrast between tumour and non-malignant changes in the lung tissue, it can be difficult to distinguish the tumour boundaries on CT images leading to large interobserver variation and differences in interpretation. Therefore the definition of the GTV has often been described as the weakest link in radiotherapy with its inaccuracy potentially leading to missing the tumour or unnecessarily irradiating normal tissue. In this article, we review the various techniques that can be used to reduce delineation uncertainties in lung cancer.

A novel system for accurate lumbar spine pedicle screw placement based on three-dimensional computed tomography reconstruction.

OBJECTIVES: The accuracy of pedicle screw placement strongly affects the outcome of spinal surgery and has mainly relied on the surgeons' experience. There is no simple, low-cost, and effective pedicle screw placement system to assist new spinal surgeons with less experience. METHODS: We designed a localization system with six parameters (starting point height [SP-H], starting point length [SP-L], transverse section angle, sagittal section angle [SSA], pedicle width [W] and height [H]) based on preoperative computed tomography reconstruction and combined it with the Roussouly classification to guide lumbar spine pedicle screw placement and analysed the change patterns of the six parameters in 50 participants. RESULTS: Based on the system, we confirmed that combining SP-H and SP-L can localize the entrance of the pedicle screw. Furthermore, we considered that SP-L and transverse section angle would be a new standard for determination of the transverse orientation of the pedicle screw. More importantly, the linear regression equations between H and W and SP-H and H were concealed. In addition, H and W can guide the appropriate selection of pedicle screw. Moreover, change patterns of SSA combined with the Roussouly classification indicate that SSA of L3 can be used as a benchmark to guide the establishment of sagittal alignment of the lumbar spine. CONCLUSIONS: Understanding and applying the six-parameter localization system are essential for achieving accuracy in lumbar spine pedicle screw placement, and the system is a useful guide in the establishment of sagittal alignment. THE TRANSLATIONAL POTENTIAL OF THIS ARTICLE: This study provides a new pedicle-screw placement system for accurate lumbar spine pedicle screw placement based on three-dimensional CT reconstruction, requiring six parameters to guide the system.

Stated Preferences for Attributes of a CYP2C19 Pharmacogenetic Test Among the General Population Presented with a Hypothetical Acute Coronary Syndrome Scenario.

BACKGROUND: Pharmacogenetic (PGx) testing identifies pharmacotherapeutic risks to permit personalized therapy. Identifying the genetic profile of patients with acute coronary syndrome (ACS) who are considered for therapy with clopidogrel (P2Y12 receptor blockers) and acetylsalicylic acid (ASA) contributes to the treatment paradigm. Patient preferences would inform a collaborative framework and by extension inform healthcare policy formulation. PURPOSE: To quantify stated preferences (willingness to pay) for attributes of a novel point-of-care PGx (CYP2C19) test using a discrete choice experiment (DCE) from the general public in Ontario, Canada, and to identify starting point bias of the cost attribute. METHODS: A web survey was created and included a questionnaire, decision board, and a DCE. DCE choice sets include the following attributes (levels): sample collection (blood, finger prick, and cheek swab), turnaround time for results (1 hr, 3 days, and 1 week), and cost in additional insurance premiums. The presence of starting point bias (cost attribute levels of $0, $1, $5 or $0, $2, $10) in the estimation of willingness to pay (WTP) was tested. RESULTS: Estimates for turnaround time and cost attributes were statistically significant. Coefficients related to the starting point bias were also significant. Approximately 67% of survey participants chose the PGx test compared to status quo treatment options. WTP for a 1 hr turnaround time compared to a 1-week turnaround time was $10.77 (95% CI 9.58 -12.25). CONCLUSION: This translational study shows preference for a point of care PGx test.

The standard sagittal starting point and entry angle for tibia intramedullary nails results in malreduction of proximal tibial fractures.

INTRODUCTION: The aim of this study was to determine the sagittal starting point and entry angle necessary for anatomic reduction in proximal tibial fractures and to compare reductions obtained using a standard versus modified sagittal entry angle. METHODS: Extra-articular proximal tibial fracture sawbone models were divided into three groups. The first group was used to determine the sagittal starting point and entry angle necessary for an anatomic reduction by inserting nails into the distal fragment and then reducing the proximal fragment over the nail. The second and third groups had nails inserted through the standard coronal and sagittal starting point using the standard sagittal entry angle (parallel to the anterior cortex) versus a more posteriorly directed modified sagittal entry angle (directed at the center of the tibia at the level of the tibia tubercle prominence). Fracture gapping and translation in the sagittal plane were measured for each group. RESULTS: Anatomic reduction was only possible with a sagittal starting point that was too posterior for actual use. The standard sagittal entry angle resulted in greater posterior fracture translation and less anterior fracture gapping then the modified sagittal entry angle, 10.6 ± 1.1 versus 1.6 ± 2.8 mm (p < 0.01) and 1.3 ± 0.5 versus 5.3 ± 2.5 mm (p = 0.01), respectively. CONCLUSION: Anatomic reduction was not achieved with the standard sagittal starting point and entry angle. Considering these finding, surgeons should have a low threshold to utilize adjunct reduction methods for these injuries.

A distal start point facilitates safer insertion of S2-alar-iliac screws fixation.

This study aimed to show that a more distal insertion of S2-alar-iliac screws (S2AI) towards the S2 foramen facilitates a more natural trajectory and results in fewer breaches of the iliac wing due to the anteroposterior relationship of the sacrum and pelvis. Thirty-six consecutive patients who had received S2AI and postoperative computed tomography (CT) imaging were retrospectively reviewed. A freehand technique was used to insert all screws. Screws were stratified into two groups (Zone A and Zone B) based on the insertion point within the sacrum. Zone A was defined as screw insertion proximal to the second sacral foramen. Zone B was defined as screw insertion at or distal to the level of the second sacral foramen. CT imaging was reviewed to identify passage of the screw through either the fibrous or bony sacroiliac joint, and to check for instrumentation breach of the iliac wing. Sixty-two S2AI in 36 patients were identified. Twenty-six screws (42%) were inserted into Zone A and 36 (58%) into Zone B. There were 11 instrumentation breaches of the iliac wing in Zone A (42%) and 0 in Zone B (p < 0.0001). In Zone A, 24 screws (92%) passed through the upper, fibrous portion of the sacroiliac joint. In Zone B, no screws passed through this region (p < 0.0001). In conclusion, insertion of S2AI at or distal to the second sacral foramen facilitates improved screw placement due to the anteroposterior relationship of the sacrum and pelvis at this level.

Evaluation of a more ventral starting point for thoracic pedicle screws: higher maximal insertional arc and more medial and safer screw angulation.

OBJECTIVETo demonstrate that a more ventral starting point for thoracic pedicle screw insertion, produced by aggressively removing the dorsal transverse process bone down to the superior articular facet (SAF), results in a larger margin for error and more medial screw angulation compared to the traditional dorsal starting point (DSP). The margin for error will be quantified by the maximal insertional arc (MIA).METHODSThe study population included 10 consecutive operative patients with adult idiopathic scoliosis who underwent primary surgery. All measurements were performed using 3D visualization software by an attending spine surgeon. The screw starting points were 2 mm lateral to the midline of the SAF in the mediolateral direction and in the center of the pedicle in the cephalocaudal direction. The DSP was on the dorsal cortex. The ventral starting point (VSP) was at the depth of the SAF. Measurements included distance to the pedicle isthmus, MIA, and screw trajectories.RESULTSTen patients and 110 vertebral levels (T1-11) were measured. The patients' average age was 41.4 years (range 18-64 years). The pedicle isthmus was largest at T1 (4.04 ± 1.09 mm), and smallest at T5 (1.05 ± 0.93 mm). The distance to the pedicle isthmus was 7.47 mm for the VSP and 11.92 mm for the DSP (p < 0.001). The MIA was 15.3° for the VSP and 10.1° for the DSP (p < 0.001). Screw angulation was 21.7° for the VSP and 16.8° for the DSP (p < 0.001).CONCLUSIONSA more ventral starting point for thoracic pedicle screws results in increased MIA and more medial screw angulation. The increased MIA represents an increased tolerance for error that should improve the safety of pedicle screw placement. More medial screw angulation allows improved triangulation of pedicle screws.

Type 2 Diabetes: When Does It Start?

OBJECTIVE: We aimed to clarify the onset of diabetes. DESIGN: Data from 27,392 nondiabetic health examinees were retrospectively analyzed for a mean of 5.3 years. Trajectories of fasting plasma glucose (FPG), body mass index (BMI), and the single point insulin sensitivity (Si) estimator (SPISE), an index of Si, 10 years before diagnosis of prediabetes (PDM; n = 4781) or diabetes (n = 1061) were separately assessed by a mixed effects model. Diabetes and PDM were diagnosed by the American Diabetes Association definition on the basis of FPG and glycosylated hemoglobin A1c values. RESULTS: In individuals who developed diabetes, mean FPG and BMI were significantly higher (P < 0.01 each) and SPISE lower than those who did not at -10 years: FPG 101.5 mg/dL vs 94.5 mg/dL, BMI 24.0 kg/m2 vs 22.7 kg/m2, and SPISE 7.32 vs 8.34, P < 0.01 each. These measurements, in subjects who developed prediabetes, were slightly but definitely different from those who did not, already at -10 years: FPG 91.8 mg/dL vs 89.6 mg/dL, BMI 22.6 kg/m2 vs 22.1 kg/m2, and SPISE 8.44 vs 8.82, P < 0.01 each. In both cases, the differences were progressively greater toward year 0, the time of diabetes, or PDM diagnosis. CONCLUSIONS: FPG was significantly elevated in those who developed diabetes at least 10 years before diagnosis of diabetes, and this was also the case in those who developed PDM. Glucose dysregulation precedes diagnosis of diabetes at least for 20 years.

[Clinical timing and benefit of antiviral treatment for hepatitis C].

Current treatments for hepatitis C include pegylated interferon-α (Peg-IFNα) and ribavirin (RBV) combination therapy and direct antiviral agents (DAAs). Antiviral treatment can be initiated after 4 to 6 months of clinical observations for patients with acute infections, but should be started as early as possible for those with chronic infections. However, for patients who are ineligible for Peg-IFN and RBV combination therapy and have no unrestricted access to DAAs, it is advised that they wait for the approval of DAAs in China if their medical condition is under control. Though, antiviral therapy should be started immediately if the disease progresses. It has been reported that there are numerous clinical benefits of antiviral treatment for hepatitis C. However, the long-term impact of DAAs treatment including efficacy and safety is limited and remains to be explored.

Widening of the safe trajectory range during subaxial cervical pedicle screw placement: advantages of a curved pedicle probe and laterally located starting point without creating a funnel-shaped hole.

OBJECTIVE The small diameter of cervical pedicles and a large transverse cervical pedicle angle are challenges that have led spinal surgeons to investigate how they could achieve a wider safety trajectory and reduce the insertion angle during cervical pedicle screw (CPS) placement. In this paper, the authors detail the advantages of using a curved pedicle probe and a laterally located entry point for overcoming these challenges. METHODS From March 2012 to May 2016, the authors performed posterior cervical fusions using CPSs on 119 consecutive patients. The lateral mass screw conversion and the CPS breach rate were analyzed. Using preoperative CT, it was determined that θlat is similar to the anatomical pedicle angle, and θmed is the minimally acceptable medial angle. The actual insertion medial angle (θins) was determined by postoperative CT. To identify how much of the medial angle on θins could be reduced from the anatomical pedicle angle (θlat), and how much closer to θmed, (θins-θmed) / (θlat-θmed) was calculated. To verify shifting of the entry point and widening of the trajectory, the mean df/Df (i.e., shifted facet point/planned facet point) values were analyzed. RESULTS The total number of planed CPSs was 759, the conversion rate was 4.61% (35/759), and the accuracy rate was 95.9% (694/724). The authors could calculate that θins could be expected near the 90%, 80%, 80%, 80%, and 110% value of θlat on C-3, C-4, C-5, C-6, and C-7 levels, respectively, with the (θins-θmed) / (θlat-θmed) equation. The mean df/Df values were 0.64, 0.62, 0.63, 0.63, and 1.24 on the C3-7 levels, respectively. CONCLUSIONS Through the use of a curved pedicle probe and a laterally located starting point, the planned and laterally located entry point medial shift was made during CPS placement. The entry point shift yielded a wider, safe trajectory and reduced the burden of making a large medial angle, similar to an anatomical cervical pedicle lateral angle, for safe CPS placement without creating a funnel-shaped hole.

Trochanteric entry femoral nails yield better femoral version and lower revision rates-A large cohort multivariate regression analysis.

INTRODUCTION: Intramedullary nailing (IMN) has become the standard of care for the treatment of most femoral shaft fractures. Different IMN options include trochanteric and piriformis entry as well as retrograde nails, which may result in varying degrees of femoral rotation. The objective of this study was to analyze postoperative femoral version between three types of nails and to delineate any significant differences in femoral version (DFV) and revision rates. MATERIALS & METHODS: Over a 10-year period, 417 patients underwent IMN of a diaphyseal femur fracture (AO/OTA 32A-C). Of these patients, 316 met inclusion criteria and obtained postoperative computed tomography (CT) scanograms to calculate femoral version and were thus included in the study. In this study, our main outcome measure was the difference in femoral version (DFV) between the uninjured limb and the injured limb. The effect of the following variables on DFV and revision rates were determined via univariate, multivariate, and ordinal regression analyses: gender, age, BMI, ethnicity, mechanism of injury, operative side, open fracture, and table type/position. Statistical significance was set at p<0.05. RESULTS: A total of 316 patients were included. Piriformis entry nails made up the majority (n=141), followed by retrograde (n=108), then trochanteric entry nails (n=67). Univariate regression analysis revealed that a lower BMI was significantly associated with a lower DFV (p=0.006). Controlling for possible covariables, multivariate analysis yielded a significantly lower DFV for trochanteric entry nails than piriformis or retrograde nails (7.9±6.10 vs. 9.5±7.4 vs. 9.4±7.8°, p<0.05). Using revision as an endpoint, trochanteric entry nails also had a significantly lower revision rate, even when controlling for all other variables (p<0.05). CONCLUSION: Comparative, objective comparisons between DFV between different nails based on entry point revealed that trochanteric nails had a significantly lower DFV and a lower revision rate, even after regression analysis. However, this is not to state that the other nail types exhibited abnormal DFV. Translation to the clinical impact of a few degrees of DFV is also unknown. Future studies to more in-depth study the intricacies of femoral version may lead to improved technology in addition to potentially improved clinical outcomes.

An Enumerative Combinatorics Model for Fragmentation Patterns in RNA Sequencing Provides Insights into Nonuniformity of the Expected Fragment Starting-Point and Coverage Profile.

RNA sequencing (RNA-seq) has emerged as the method of choice for measuring the expression of RNAs in a given cell population. In most RNA-seq technologies, sequencing the full length of RNA molecules requires fragmentation into smaller pieces. Unfortunately, the issue of nonuniform sequencing coverage across a genomic feature has been a concern in RNA-seq and is attributed to biases for certain fragments in RNA-seq library preparation and sequencing. To investigate the expected coverage obtained from fragmentation, we develop a simple fragmentation model that is independent of bias from the experimental method and is not specific to the transcript sequence. Essentially, we enumerate all configurations for maximal placement of a given fragment length, F, on transcript length, T, to represent every possible fragmentation pattern, from which we compute the expected coverage profile across a transcript. We extend this model to incorporate general empirical attributes such as read length, fragment length distribution, and number of molecules of the transcript. We further introduce the fragment starting-point, fragment coverage, and read coverage profiles. We find that the expected profiles are not uniform and that factors such as fragment length to transcript length ratio, read length to fragment length ratio, fragment length distribution, and number of molecules influence the variability of coverage across a transcript. Finally, we explore a potential application of the model where, with simulations, we show that it is possible to correctly estimate the transcript copy number for any transcript in the RNA-seq experiment.

Clinical timing and benefit of antiviral treatment for hepatitis C / 中华肝脏病杂志

Current treatments for hepatitis C include pegylated interferon-α (Peg-IFNα) and ribavirin (RBV) combination therapy and direct antiviral agents (DAAs). Antiviral treatment can be initiated after 4 to 6 months of clinical observations for patients with acute infections, but should be started as early as possible for those with chronic infections. However, for patients who are ineligible for Peg-IFN and RBV combination therapy and have no unrestricted access to DAAs, it is advised that they wait for the approval of DAAs in China if their medical condition is under control. Though, antiviral therapy should be started immediately if the disease progresses. It has been reported that there are numerous clinical benefits of antiviral treatment for hepatitis C. However, the long-term impact of DAAs treatment including efficacy and safety is limited and remains to be explored.

Influenced from the start: anchoring bias in time trade-off valuations.

PURPOSE: The de facto standard method for valuing EQ-5D health states is the time trade-off (TTO), an iterative choice procedure. The TTO requires a starting point (SP), an initial offer of time in full health which is compared to a fixed offer of time in impaired health. From the SP, the time in full health is manipulated until preferential indifference. The SP is arbitrary, but may influence respondents, an effect known as anchoring bias. The aim of the study was to explore the potential anchoring effect and its magnitude in TTO experiments. METHODS: A total of 1249 respondents valued 8 EQ-5D health states in a Web study. We used the lead time TTO (LT-TTO) which allows eliciting negative and positive values with a uniform method. Respondents were randomized to 11 different SPs. Anchoring bias was assessed using OLS regression with SP as the independent variable. In a secondary experiment, we compared two different SPs in the UK EQ-5D valuation study TTO protocol. RESULTS: A 1-year increase in the SP, corresponding to an increase in TTO value of 0.1, resulted in 0.02 higher recorded LT-TTO value. SP had little impact on the relative distance and ordering of the eight health states. Results were similar to the secondary experiment. CONCLUSION: The anchoring effect may bias TTO values. In this Web-based valuation study, the observed anchoring effect was substantial. Further studies are needed to determine whether the effect is present in face-to-face experiments.

The ventral lamina and superior facet rule: a morphometric analysis for an ideal thoracic pedicle screw starting point.

BACKGROUND CONTEXT: With the increasing popularity of thoracic pedicle screws, the freehand technique has been espoused to be safe and effective. However, there is currently no objective, definable landmark to assist with freehand insertion of pedicle screws in the thoracic spine. With our own increasing surgical experience, we have noted a reproducible and unique anatomic structure known as the ventral lamina. PURPOSE: We set out to define the morphologic relationship of the ventral lamina to the superior articular facet (SAF) and pedicle, and describe an optimal medial-lateral pedicle screw starting point in the thoracic spine. STUDY DESIGN: We conducted an in vitro fresh-frozen human cadaveric study. METHODS: One hundred fifteen thoracic spine vertebral levels were evaluated. After the vertebral body was removed, Kirschner wires were inserted retrograde along the four boundaries of the pedicle. Using digital calipers, we measured width of the SAF and pedicle at the isthmus, and from the borders of the SAF to the boundaries of the pedicle. We calculated the morphologic relationship of the ventral lamina and the center of the pedicle (COP) to the SAF. RESULTS: Two hundred twenty-nine pedicles were measured, with one pedicle excluded because of fracture of the SAF during disarticulation. The ventral lamina was clearly identifiable at all levels, forming the roof of the spinal canal and confluent with the medial pedicle wall (MPW). The mean distance from the SAF midline to the MPW was 1.36±1.23 mm medial. The MPW was lateral to SAF midline in 34 pedicles (14.85%) and, on average, was a distance of 0.52±0.51 mm lateral. The mean distance from the SAF midline to the COP was 2.17±1.38 mm lateral. The COP was medial to SAF midline in only 11 pedicles (4.80%). CONCLUSIONS: The ventral lamina is an anatomically reproducible structure located consistently medial to the SAF midline (85%). We also found the COP consistently lateral to the SAF midline (95%). Based on these morphologic findings, the medial-lateral starting point for thoracic pedicle screws should be 2 to 3 mm lateral to the SAF midline (superior facet rule), allowing screw placement in the COP and avoiding penetration into the spinal canal.

Comparative Study of Postoperative Analgesic Effect of IV-PCA According to Timing of Infusion in Patients with Total Abdominal Hysterectomy / 기본간호학회지

PURPOSE: This study was designed to verify preemptive effects of intravenous patient-controlled analgesia (IV-PCA) infusion on postoperative pain in women having a total abdominal hysterectomy. METHOD: The research design was a nonequivalent control group post test only design. The participants in this study were 50 women who were scheduled for a total abdominal hysterectomy at a University affiliated Hospital in Suwon, Korea. The subjects were divided into two groups. For the experimental group, IV-PCA infusion was started before the skin incision and for the control group, IV-PCA infusion was started after the skin was closed. Each group was evaluated in terms of pain score by the visual analogue scale (VAS) and the number of times they pushed the button for IV-PCA at postoperative hours 1, 2, 3, 6, 12, and 24. The data were collected from July 1 to December 10, 2001. Collected data was analyzed by SPSS/PC+ program. RESULT: 1. There was no difference between the two groups, over six points for the number of times the control button for IV-PCA was used. Group differences and interaction effect were not significant. 2. There was no significant difference in pain scores between the two groups, over seven time points. A significant interaction effect was observed between groups and measurement points in time. 3. There was a significant difference in the requirements for additional analgesia between the two groups, 32% of the control group received additional analgesia. CONCLUSION: Preemptive analgesics administration may have a better effect in relieving postoperative pain than the usual analgesic treatment which is started after surgery.