Measurement Error and Misclassification in Orthopedics: When Study Subjects are Categorized in the Wrong Exposure or Outcome Groups

Datasets available for orthopedic research often contain measurement and misclassification errors due to errors in data collection or missing data. These errors can have different effects on the study results. Measurement error refers to inaccurate measurement of continuous variables (eg, body mass index), whereas misclassification refers to assigning subjects in the wrong exposure and/or outcome groups (eg, obesity categories). Misclassification of any type can result in underestimation or overestimation of the association between exposures and outcomes. In this article, we offer practical guidelines to avoid, identify, and account for measurement and misclassification errors. We also provide an illustrative example on how to perform a validation study to address misclassification based on real-world orthopedic data. Please visit the following https://youtu.be/9-ekW2NnWrs or videos that explain the highlights of the article in practical terms.     

Statistical fallacies in orthopedic research

Background:

A large number of statistical fallacies occur in medical research literature. These are mostly inadvertent and occur due to lack of understanding of the statistical concepts and terminologies. Many researchers do not fully appreciate the consequence of such fallacies on the credibility of their report.

Materials and Methods:

This article provides a general review of the issues that could give rise to statistical fallacies with focus on orthopedic research. Some of this is based on real-life literature and some is based on the actual experiences of the author in dealing with medical research over the past three decades. The text is in teaching mode rather than research mode.

Results:

Statistical fallacies occur due to inadequate sample that is used for generalized conclusion; incomparable groups presented as comparable; mixing of two or more distinct groups that in fact require separate consideration; misuse of percentages, means and graphs; incomplete reporting that suppresses facts; ignoring reality and depending instead on oversimplification; forgetting baseline values that affect the outcome; misuse of computer packages and use of black-box approach; misuse of P-values that compromises conclusions; confusing correlation with cause-effect; and interpreting statistical significance as medical significance.

Conclusion:

Mere awareness of the situations where statistical fallacies can occur may be adequate for researchers to sit up and take note while trying to provide a credible report.     

Normative Data of the Hip Disability and Osteoarthritis Outcome Score,JR in a Healthy United States Population

BackgroundPatient-reported outcome measures (PROMs) play a vital role in the care we provide our patients. To help understand the application of PROMs in arthroplasty, normative and benchmark data to serve as a comparison to patients presurgery and postsurgery would be extremely valuable. We collected normative data of the Hip Disability and Osteoarthritis Outcome Score (HOOS), JR on a healthy population, greater than 17 years of age, in the United States devoid of hip injury and/or surgery.MethodsThis is a cross-sectional study, where hard copy surveys were administered to 1140 patients, being seen for an orthopedic issue unrelated to their hip, and nonpatient visitors in July 2018 at an outpatient orthopedic clinic in a suburban metropolitan city. Participants were eligible if they self-reported a medical history negative for hip arthroplasty, current hip pain/disability, or hip procedure (surgery or injection) within the past year. Mean, standard deviation, 95% confidence intervals, and ranges on the HOOS, JR interval scores were calculated by sex, age decade, body mass index (BMI), reason for visit, history of orthopedic procedure, and medical history.ResultsWe included 425 men and 575 women in the final study cohort. Women aged between 70+ years reported the lowest mean interval score (mean = 89.8). Overall women scored lower as well (93.3 vs 95.7, P = .001). There was not a statistical difference between the interval scores by tobacco consumption (93.5 vs 94.4, P = .49) and between patients versus nonpatient visitors (94.2 vs 94.5, P = .672). Lower scores were observed in participants with a past nonhip orthopedic procedure (92.6 vs 94.9, P = .016), with a medical history of a chronic illness (92.5 vs 95.9, P = <.001), and classified as obese (BMI > 30) (91.7 vs 95.2, P < .001). On regression analysis, there was a decrease of 0.3 and 0.1 in the interval score for each unit of BMI and age by year, respectively (P < .001).ConclusionThis study provides normative reference values for the HOOS, JR in a US population from a suburban metropolitan city for individuals greater than 17 years of age. These scores can facilitate physician-patient shared decision-making to help patients understand expectations after hip arthroplasty in respect to PROMs.     

经皮无水乙醇+碘油注射联合超声消融治疗子宫肌瘤

目的 评价经皮无水乙醇(PEI)+碘油注射联合HIFU治疗“HIFU-难治型“子宫肌瘤的有效性及安全性.方法 将75例单发子宫肌瘤患者按照治疗时间顺序分为研究组和对照组,研究组采用PEI+碘油联合HIFU治疗,对照组采用HIFU治疗,将两组分为T2WI高信号亚组、后壁亚组、T2WI高信号亚组+后壁亚组,分析“HIFU-难治型”肌瘤的疗效及安全性.结果 研究组及对照组消融率、肌瘤1个月体积缩小率和单位体积治疗时间差异均有统计学意义(P均 <0.05).研究组及对照组T2WI高信号亚组消融率、单位体积治疗时间差异均有统计学意义(P均 <0.05).研究组及对照组后壁亚组消融率、肌瘤1个月体积缩小率差异有统计学意义(P <0.05).研究组及对照组T2WI高信号+后壁亚组消融率、肌瘤1个月体积缩小率、单位体积治疗时间差异均有统计学意义(P <0.05).研究组与对照组总体并发症发生率分别为84.21%(32/38)、70.27%(26/37;P >0.05),研究组及对照组T2WI高信号+后壁亚组并发症发生率为100%(14/14)、66.67%(6/9,P <0.05),但均为轻度.结论 PEI可提高HIFU治疗子宫肌瘤的疗效,可作为治疗“HIFU-难治型”子宫肌瘤的一种辅助手段,但需注意并发症的防控.     

Adjusted Survival Curves Improve Understanding of Multivariable Cox Model Results

Kaplan-Meier survival curves are the most common methods for unadjusted group comparison of outcomes in orthopedic research. However, they may be misleading due to an imbalance of confounders between patient groups. The Cox model is frequently used to adjust for confounders, but graphical display of adjusted survival curves is not commonly utilized. We describe the circumstances when adjusted survival curves are useful in orthopedic research, describe and use 2 different methods to obtain adjusted curves, and illustrate how they can improve understanding of the multivariable Cox model results. We further provide practical strategies for identifying the need for and performing adjusted survival curves. Please visit the following https://youtu.be/ys0hy2CiMCA for a video that explains the highlights of the paper in practical terms.     

A comparative study of medial versus lateral arthroscopic partial meniscectomy on stable knees: 10-year minimum follow-up

Purpose: Our goal was to compare results of partial medial arthroscopic meniscectomy with results of partial lateral arthroscopic meniscectomy and to determine prognostic factors. Type of Study: Retrospective comparative study with statistical analysis. Methods: In this study, 362 medial and 109 lateral isolated arthroscopic meniscectomies are presented with a minimum follow-up time of 10 years. All knees were stable with no previous surgery or traumatic lesion. Results: In this study, 95% of the patients were very satisfied or satisfied with the results of the medial meniscectomy, and 95.5% with results of the lateral meniscectomy (P = .32). According to grades 1 and 2 of the Intenational Knee Documentation Committee (IKDC) form, 85.8% of the medial meniscectomy group were free of any symptoms, as were 79.7% of the lateral meniscectomy group (P = .11). Radiologic changes after medial and lateral meniscectomy were found in 21.5% and 37.5%, respectively (P = .11). The rates of radiologic changes in patients in whom the contralateral knee was radiologically normal were 22.3% and 39%, respectively (P = .016). The rate of repeat surgeries for osteoarthritis was less than 0.2%. Conclusions: Subjective and clinical results after medial or lateral meniscectomy are quite similar, but radiologic results are significantly worse after lateral meniscectomy. The most accurate way to determine the degeneration caused by the meniscectomy is to evaluate joint space narrowing in patients in whom the contralateral knee was radiologically normal. Otherwise, partial medial or lateral meniscectomy are well tolerated. A better prognosis can be predicted for a patient with an isolated medial meniscal tear with one or more of the following factors: age less than 35 years, a vertical tear, no cartilage damage, and an intact meniscal rim at the end of the meniscectomy. With an isolated lateral meniscal tear, a better prognosis can be predicted if the patient is young and has an intact meniscal rim at the end of the meniscectomy.     

A multidisciplinary approach to the development of a cervical spine clearance protocol: process,rationale, and initial results

Background/Purpose: Assessment of potential spine injuries is inconsistent and controversial. Subsequent morbidity includes prolonged immobilization and missed injuries. To address these issues, a multidisciplinary team was organized to design a cervical spine management/clearance pathway. The process, algorithm, and initial results are described. Methods: Team members consisted of pediatric surgeons, orthopedic surgeons, neurosurgeons, emergency room physicians, and trauma nurse practitioners. Nationwide standards, guidelines, and experiences across disciplines were reviewed, and a consensus pathway evolved for cervical spine clearance in children 8 years and younger. A short-term retrospective review (5 months) was performed to assess initial performance. Time required for clearance, number and type of imaging studies, and number of missed injuries were compared between a group of patients before (n = 71) and after (n = 56) the implementation of the pathway. Results: Strict guidelines for cervical spine immobilization and clearance criteria were defined. After implementation of this pathway, time required for cervical clearance in nonintubated children decreased (before, 12.3 [plusmn] 1.5 v after, 7.5 [plusmn] 0.9 hours; P = .014). A clear trend toward earlier clearance in intubated patients existed (before [n = 6], 40.0 [plusmn] 16.8 v after [n = 6], 19.4 [plusmn] 8.1 hours; P = .10); there need to be larger numbers to determine statistical significance. The 2 study groups were similar in age; mechanism of injury; Glasgow coma scale score; and number of plain x-rays, computed tomography scans, and magnetic resonance imaging studies obtained. Neither group had missed injuries. Conclusions: standards for cervical spine immobilization, assessment, and clearance. Implementation of such guidelines decreased time for cervical spine clearance, and ongoing analysis of sensitivity is encouraging. J Pediatr Surg 38:358-362.     

A study of attributable variables impacting orthopedic trauma surgical training

Purpose: In medical colleges, resident training programs must provide adequate surgical experiences, making them qualified at the end of residency program. It is generally believed that it would take more time for a surgical resident to perform surgical procedures than a board-certified surgeon. There is no current benchmark with regards to operative time and surgical cases involving orthopedic surgery residents. In this study, we focused on two key aspects of surgical training variables, namely, surgical duration & C-arm shoots when the procedure is done by a faculty surgeon in comparison to done by an orthopedic resident under supervision of faculty surgeon. Methods: It is an observational prospective study, we observed patients undergoing 1 of 5 common orthopedic trauma operations in a community teaching hospital. We recorded two variables, ‘skin to skin’ surgical duration & number of image intensifier television/C-arm shoots of faculty surgeons and orthopedic resident (postgraduate-3yr) under supervision of faculty surgeon. We calculated mean dif ference of two variables with or without resident & determined statistical significance, we also compared functional outcome at final follow-up. Results: The total number of procedure observed was 402. On observing summarized results of all surgical procedures, faculty surgeons took on an average 33 min lesser (p < 0.05) & on an average 37 lesser number of shoots (p < 0.05) than resident surgeons. The difference in surgical duration tended to increase with the greater complexity of the surgical dissection. The difference in number of C-arm shoots tended to increase with the increase in surgical duration in closed procedures. In all the five procedures there was no significant difference (p > 0.05) in functional outcome of cases performed by faulty surgeon and resident. Conclusion: Little data has been previously published regarding the impact of teaching orthopedic resident in operating room. We demonstrate that resident participation increases the procedure time for commonly performed orthopedic procedures and also the number of C-arm shoots, hence there is a need for technical training facilities outside the operating room such as in cadaveric labs, saw bone labs & virtual surgery simulation. Also the preoperative plan should be thoroughly discussed by faculty surgeon with residents.     

The Fragility of Statistical Findings in Distal Radius Fractures: A Systematic Review of Randomized Controlled Trials

PurposeProbability analysis with reporting of P values is often used to determine the statistical significance of study findings in the orthopedic literature. The fragility index (FI) has been used to evaluate the robustness of a significant result. The purpose of this study was to determine the utility of applying a fragility analysis to randomized controlled trials (RCTs) evaluating distal radius fractures (DRFs).MethodsWe identified all dichotomous outcome data for randomized controlled trials of distal radius fractures (DRFs) published in 13 orthopedic journals from 2000 to 2020. The fragility index (FI) was determined by the number of event reversals required to change a P value from less than 0.05 to greater than 0.05, or vice-versa. The associated fragility quotient (FQ) was determined by dividing the FI by the sample size. The interquartile ranges (IQR) for the FI and FQ were calculated as the difference between the 25th and 75th percentiles for the overall study.ResultsOf the 7352 studies screened, 221 met the search criteria, with 34 randomized controlled trials evaluating distal radius fractures and 151 total outcome events included for analysis. The overall FI was 9 (IQR 6.5–11) with an associated fragility quotient of 0.097 (IQR 0.060–0.140). However, a majority of outcomes (78.8%) were not significant. Fragility analysis of statistically significant outcomes had an FI of 4 (IQR 1–10). All of the studies reported lost to follow-up (LTF) data where 20.6% reported lost to follow-up of greater or equal to 9.ConclusionThe RCTs in distal radius fracture outcomes have comparable statistical robustness to literature in other orthopedic surgical specialties, are not as statistically stable as previously thought and should be interpreted with caution. We recommend that orthopedic literature report the FI and FQ along with the P values to help the reader draw reliable conclusions based on the fragility of outcome measures.Level of EvidenceLevel I     

Conflit sous-acromial : influence de la morphologie de la voûte acromiocoracoïdienne sur la valeur fonctionnelle de l'épaule

Subacromial impingement: influence of coracoacromial arch geometry on shoulder function. Objective. To look for correlations between radiological coracoacromial arch geometry and shoulder function in patients with subacromial impingement syndrome. Patients and methods. During a prospective study of the efficacy of arthroscopic subacromial decompression, we evaluated the function of the treated and contralateral shoulders using Constant's functional score and confronted the results to several radiographic parameters reflecting coracoacromial arch geometry. Results. Constant's score values were low (42±15) because of pain and a low level of activity. Males had significantly higher scores than females. Constant's score was unaffected (P>0.05) by patient age, the side, the level of activity, or the duration of symptoms, but was significantly influenced by the orientation of the acromion with respect to the scapular spine and to the vertical scapular axis. The preoperative Constant's score was significantly higher in patients with a more horizontal acromion (P=0.01). A very tight correlation was found between the preoperative Constant's score and the angle between the acromion and scapular spine (P=0.0003). Conclusion. Based on our results, we defined an open and a closed coracoacromial arch geometry. Coracoacromial arch geometry is correlated with shoulder function syndrome and can assist in the interpretation of rotator cuff impingement.     

Pain,function, and radiographic disease in trapeziometacarpal osteoarthritis

IntroductionTrapeziometacarpal joint osteoarthritis (OA) produces significant functional impairment due to pain and loss of strength in both power and precision grips, but few studies have related radiographic scores to functional and pain-based measures.PurposeTo investigate the association between markers of radiographic disease and outcomes for symptomatic and functional disease.Study DesignThis study in an exploratory analysis of baseline data from the first 100 participants in a clinical trial evaluating the efficacy of combined conservative therapies for base of thumb OA (COMBO).MethodsFunctional Index for Hand Osteoarthritis (FIHOA) scores and Visual Analogue Scale (VAS) scores for pain were recorded for the index hand. Bilateral isometric grip and tip-pinch strength measurements were taken, as well as posteroanterior and Eaton stress-view hand radiographs. Generalized estimating equations (GEEs), univariate, and multivariate analyses were used according to whether the data were bilateral or unilateral.ResultsA total of 79 females and 21 males were included, with a median Kellgren-Lawrence (KL) grade of 3 in the index hand. Higher KL and Eaton grades were associated with lower grip strength in the GEE analysis (B-coefficients of -1.25 and -1.16, and P-values of .002 and .010, respectively). Higher KL grade was also associated with poorer function and higher pain levels in the multivariable analysis (B-coefficients of 1.029 and 3.681, and P-values of .021 and .047, respectively). Lower radial subluxation ratios were associated with lower grip strength in the GEE analysis, and higher pain scores in the multivariable analysis (B-coefficients of 2.06 and -42.1, and P-values of .006 and .031, respectively). Greater pain scores were also associated with poorer function (B-coefficient 0.082, P-value .001).ConclusionMore advanced radiographic trapeziometacarpal OA severity is associated with lower grip strength and poorer self-reported functional outcomes. Lower subluxation ratios were associated with higher pain scores and lower grip strength.     

Long-term results of arthroscopic resection of the distal clavicle with concomitant subacromial decompression

Purpose: The goal of the study was to evaluate the long-term outcome of combined arthroscopic distal clavicle excision and subacromial decompression. Type of Study: Retrospective, long-term cohort evaluation. Methods: Twenty patients with an average follow-up of 6 years (range, 3.9 to 9 years) were reviewed. All patients had ipsilateral impingement syndrome and acromioclavicular joint disease at the time of surgery and underwent arthroscopic subacromial decompression combined with arthroscopic distal clavicle excision. All patients returned for evaluation in person, in addition to filling out a questionnaire incorporating the University of California, Los Angeles (UCLA), and Constant scoring systems. Preoperative and postoperative radiographs were available for all patients. Results: Postoperatively, all patients had pain relief and were satisfied with the result. The average postoperative UCLA Shoulder score was 29.8 ± 0.6, compared with 17.5 ± 3.0 before surgery (P = .001). The Constant Shoulder score averaged 98.5 ± 2.1 postoperatively, compared with 70.5 ± 11.2 preoperatively (P = .001). There was 100% good to excellent results using both scoring systems. Individual components of the UCLA scoring system (pain, function, and power) all showed significant postoperative improvement (P = .001). Constant categories of pain, activities of daily living, range of motion, and power also improved. Follow-up radiographs showed maintenance of the resected distal clavicle in 19 patients. Five patients (25%) had radiographic evidence of calcific density distal to the resected clavicle but were asymptomatic. Conclusions: The long-term results of arthroscopic resection of the distal clavicle with concomitant subacromial decompression are uniformly good or excellent. Impingement and acromioclavicular joint disease frequently coexist and should be identified and treated concurrently.     

Arthroscopic repair of massive,contracted, immobile rotator cuff tears using single and double interval slides: technique and preliminary results

Purpose: The purpose of this study is to describe the technique and review the preliminary results of arthroscopic repair of massive, contracted, immobile rotator cuff tears using an interval slide technique. Type of Study: Case series. Methods: From January 1999 to December 2000, the senior author (S.S.B.) performed arthroscopic rotator cuff repair on 94 massive rotator cuff tears. Of these, 9 (9.6%) were massive, severely contracted rotator cuff tears and required repair using an interval slide technique. A single interval slide was used in 6 patients, and a double interval slide was used in 3 patients. All patients were evaluated preoperatively and postoperatively using a modified University of California Los Angeles (UCLA) scoring system. Results: At a mean follow-up time of 17.9 months (range, 10–24 months), 8 of 9 patients were satisfied with the procedure. The mean UCLA score increased from 10.0 preoperatively to 28.3 postoperatively (P < .00001). All patients showed some improvement in active motion, strength, or function. Active forward flexion improved significantly, from a preoperative mean of 108° to a postoperative mean of 146.1° (P = .025). Active external rotation increased significantly from a preoperative mean of 24.4° to a postoperative mean of 35.0° (P = .04). A significant increase in strength grade (2.2 to 3.6; P < .005) and function (2.5 to 7.1; P < .0005) were also seen. We encountered no significant complications to the procedure. Conclusions: The interval slide technique provides a method of mobilization of massive, severely contracted, immobile rotator cuff tears allowing repair of previously irreparable tears. This technique, in conjunction with arthroscopic rotator cuff repair, may provide patients with improvements in pain, motion, strength, and overall shoulder function. Level of Evidence: Level IV.     

Ultrasonic surgery: Power quantification and efficiency optimization

Background: Ultrasonic surgery systems present the surgeon with a host of control parameters and design choices that may directly affect clinical outcome. These include amplitude setting, probe/cannula tip design, probe/cannula diameter, vibration frequency, and mode of energy delivery. Currently, no commonly accepted objective means of measurement (or measurements) exists that can be used to assess the impact of these control parameters, to compare different systems/designs, or to provide a common basis for interpreting clinical outcomes. Objectives: The goals of this study were to develop the following as functions of the surgeon's choice of control parameters: (1) a measure of the vibratory power that could potentially be applied to the subcutaneous tissues, and (2) a measure of the effectiveness of the applied vibratory power. Methods: The vibratory power produced by 4 commercially available ultrasonic surgery systems was quantified on the basis of a measured temperature rise in a known volume of water with various combinations of ultrasonic probes/cannulas. The data were normalized to develop a measure of energy efficiency. Results: The data show that ultrasonic surgical probes/cannulas have zones of high and low efficiency, that the vibratory power and energy efficiency that may be applied to tissues varies widely over the range of the possible control parameters, and that zones of optimal efficiency may be developed. Conclusions: Two simple measurements referred to as H2O power and energy efficiency provide a basis for objective comparison of different ultrasonic instrumentation. These measurements will assist in standardizing clinical observations. (Aesthetic Surg J 2001;21:233-241.)     

Vastus lateralis release for painful bipartite patella

Purpose: The purpose of this study was to evaluate the efficacy of vastus lateralis release for painful bipartite patella. We have also compared the results of open method versus arthroscopic method using a holmium:YAG laser system (OmniPulse Holmium Laser System; Trimedyne Inc, Irvine, CA). Type of Study: This study was a nonrandomized control and cross-over trial. Methods: Fifteen patients with 17 painful bipartite patella who underwent vastus lateralis release were included in this study. The average age of patients was 14.3 ± 2.2 years. In 7 knees of 6 patients, vastus lateralis release was performed through a skin incision over the bipartite fragment, and in 10 knees of 9 patients, we performed the procedure arthroscopically with the holmium:YAG laser. We assessed clinical and radiographic data of the patients chronologically in both groups. Results: In all patients, pain over the fragment disappeared within 4 weeks after the operation, and all returned to their previous sports activities at an average of 3.1 ± 0.9 months postoperatively. Clinical assessment was classified as excellent in 13 knees and good in 4 knees. Bone union at 6 months after the operation was complete in 11 knees (64.7%) and incomplete in 6 knees (35.3%), and none of the knees was graded as not healed. Bone union in patients with an age of 15 or younger was significantly better than that in patients over 15 years of age (P <.05). Release under arthroscopy showed statistically better results in duration of knee effusion (P <.05), return of circumference of thigh (P <.05), and return of muscle strength (P <.05). Conclusions: Because vastus lateralis release is less invasive surgery with good results, we conclude that this procedure can be a first choice of operative treatment for painful bipartite patella.Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 18, No 4 (April), 2002: pp 404–411     

Obesity in orthopedic patients

BackgroundTo investigate the correlation between various orthopedic conditions and overweight/obesity at the Department of Orthopedics, Malmö University Hospital Sweden. Obesity is associated with numerous major medical conditions. Although the relationship between gonarthrosis and osteoarthritis and body mass index (BMI) is well recognized, other orthopedic conditions have been less well studied.MethodsWe compared the BMI of 2 orthopedic outpatient cohorts of a local community-based urban reference population. Study 1 identified the medical records of 79 consecutive emergency room patients (45 women; age 27–49 years) with the diagnosis of ankle fracture, for whom we calculated the BMI from the self-reported height and weight. Study 2 prospectively weighed and measured 647 consecutive patients (316 women, age 20–80 years) attending our orthopedic specialty clinic for various recent and chronic conditions during a 3-week period.ResultsThe mean BMI was 1.9 units greater in the patients with ankle fractures than in the age- and gender-matched controls (P <.001). The odds ratio for a BMI >30 kg/m² was 3.46. The orthopedic clinic patients had a mean BMI 1.4 units greater than the reference population (P <.001), with an odds ratio of 2.3 for a BMI >30 kg/m² (P <.001).ConclusionThe results of these pilot studies have demonstrated significant relationships between obesity and common orthopedic conditions that contribute to the global excess medical expenditures attributable to obesity.     

Misinterpretation of P Values and Statistical Power Creates a False Sense of Certainty: Statistical Significance,Lack of Significance,and the Uncertainty Challenge

Despite great advances in our understanding of statistics, a focus on statistical significance and P values, or lack of significance and power, persists. Unfortunately, this dichotomizes research findings comparing differences between groups or treatments as either significant or not significant. This creates a false and incorrect sense of certainty. Statistics provide us a measure of the degree of uncertainty or random error in our data. To improve the way in which we communicate and understand our results, we must include in reporting a probability, or estimate, of our degree of certainty (or uncertainty). This will allow us to better determine the risks and benefits of a treatment or intervention. Approaches that allow us to estimate, account for, and report our degree of uncertainty include use of confidence intervals, P-value functions, and Bayesian inference (which incorporates prior knowledge in our analysis of new research data). Surprise values (S values, which convert P values to the number of successive identical results of flips of a fair coin) express outcomes in an intuitive manner less susceptible to dichotomizing results as significant or not significant. In the future, researchers may report P values (if they wish) but could go further and provide a confidence interval, draw a P-value function graph, or run a Bayesian analysis. Authors could calculate and report an S value. It is insufficient to mindlessly report results as significant versus not significant without providing a quantitative estimate of the uncertainty of the data.     

Connective tissue growth factor expression is decreased in acute ascending aortic dissections and increased in degenerative ascending aortic aneurysms

Purpose. Both aortic aneurysms and aortic dissections exhibit abnormal extracellular matrix properties. Connective tissue growth factor (CTGF) can induce connective tissue cell proliferation and extracellular matrix synthesis. The role of CTGF in thoracic aortic disease has never been investigated. We sought to compare the expression of CTGF in degenerative ascending aortic aneurysms and ascending aortic dissection. Methods. Intraoperative samples of ascending aorta were obtained from 47 patients: 16 patients had ascending aortic aneurysms with medial degeneration, 10 had acute aortic dissection, 9 had aneurysms due to chronic dissection. Control ascending aorta was obtained from organ donors and heart transplant recipients (n = 10). Patients with Marfan syndrome were excluded from this study. CTGF mRNA expression within aortic wall was semiquantitatively determined by real-time RT-PCR using GAPDH as the internal standard. Results. There was a significant increase in CTGF mRNA in degenerative aneurysms compared to control tissue (P = 0.04). Conversely, patients with acute dissection had decreased CTGF mRNA expression compared with nondissection aneurysms (P = 0.019) and controls (P = 0.06). The increase in CTGF expression in chronic dissections compared to acute dissections approached statistical significance (P = 0.075). Conclusions. The altered tissue levels of CTGF in aneurysms and dissections suggest possibly different molecular pathology in these aortic disorders. Further investigation regarding the role of CTGF in thoracic aortic disease is warranted.     

A survey of the tension applied to a doubled hamstring tendon graft for reconstruction of the anterior cruciate ligament

Purpose: Currently there is no consensus regarding the amount of tension to apply to a graft when reconstructing the anterior cruciate ligament (ACL). We undertook a study to determine whether sports trained orthopedic surgeons tension hamstring tendon grafts maximally during ACL reconstruction, and also whether surgeons tend to load their grafts within a narrow range of tensions. Type of Study: Cross-sectional study. Methods: One fresh-frozen cadaveric knee with appropriately placed femoral and tibial tunnels and five pairs of preconditioned semitendinosus and gracilis tendons were used. Custom-made computer software and a custom-made, load measurement device was employed. Thirteen orthopedic sports medicine physicians from our community took part in the study. Surgeons were asked to tension the graft as they would in surgery and were then asked to tension the graft maximally. Results: The mean and standard deviation of the normal tension (14.8 ± 7.2 lb) was significantly less (P = .005) than the mean maximal tension (22.3 ± 6.9 lb). Conclusions: This study shows that most ACL surgeons do not tension their graft maximally. Moreover, graft tensioning is highly variable among sports medicine orthopedists. These findings revisit the question as to whether tension should be more accurately measured and controlled for intraoperatively.     

三维能量多普勒超声定量评估正常胎盘血流灌注和胎盘植入

目的采用三维能量多普勒超声(3D-PDU)观察正常前壁胎盘血流灌注情况,并对胎盘植入进行产前评估。方法将232名11~40孕周孕妇的正常单胎妊娠前壁胎盘作为正常对照组,10例经手术或病理证实为胎盘植入孕妇的胎盘作为观察组。采用3D-PDU的三维血管模式(3D Angio),测量两组血管化指数(VI)、血流指数(FI)、血管化-血流指数(VFI)。分析正常对照组胎盘血流参数与孕龄的关系,并对比两组测量参数的差异。结果正常对照组胎盘VI、FI、VFI与孕龄相关(r=0.678、0.766、0.410,P均0.01),且VFI与VI相关(r=0.800,P0.01)。观察组与正常对照组胎盘3D-PDU血流参数(VI、FI、VFI)差异均有统计学意义(P均0.05)。结论 3D-PDU可定量分析正常前壁胎盘血流灌注情况,为产前诊断胎盘植入提供量化评估依据。