David Biau

Use of the Learning Curve-Cumulative Summation test for quantitative and individualized assessment of competency of a surgical procedure in obstetrics and gynecology: fetoscopic laser ablation as a model

OBJECTIVE We sought to determine the learning curve (LC) for fetoscopic laser photocoagulation (FLP) as a model for the evaluation of training in surgical procedures. STUDY DESIGN A retrospective review of consecutive case series of FLP from 2 centers with 3 operators (operator I [O-I], observer trained; operator II [O-II], hands-on trained; and operator III [O-III], clinical fellow) was performed and the LC-cumulative summation (CUSUM) test was plotted. RESULTS The acceptable and unacceptable success rates for at least 1 fetus survival after FLP were set at 82% and 70%, respectively, from a systematic review. A total of 171 consecutive cases were performed by the 3 operators (O-I, 91; O-II, 49; and O-III, 31). From LC-CUSUM test O-I needed 60 procedures, O-II needed 20 procedures, and O-III needed 20 procedures to reach an acceptable performance rate for at least 1 survivor. CONCLUSION The LC-CUSUM test can be used to accurately assess the LC in a surgical procedure in obstetrics and gynecology. Hands-on trained operators exhibit a shorter LC.

One-Stage Exchange Arthroplasty for Chronic Periprosthetic Hip Infection: Results of a Large Prospective Cohort Study

BACKGROUND Exchange arthroplasty of one or two stages is required for the treatment of chronic periprosthetic joint infections. Two-stage exchange is costly and has high morbidity with limited patient mobility between procedures. One-stage exchange has been promoted by several European teams as the preferred alternative. The aim of this study was to prospectively analyze the outcome of patients with a periprosthetic hip infection treated with one-stage exchange arthroplasty. METHODS We performed a prospective cohort study in a French referral center for osteoarticular infections including all periprosthetic hip infections treated with one-stage exchange arthroplasty from November 2002 to March 2010. Direct exchange was performed in chronic periprosthetic hip infection with no or minor bone loss and preoperative identification of a microorganism from joint fluid aspirate. No antibiotic-loaded bone cement was used. Antibiotic therapy was administered for twelve weeks: intravenously for four to six weeks, followed by an oral regimen for six to eight weeks. Follow-up was a minimum of two years. The following events were noted: relapse, new infection, joint revision for mechanical reasons, and periprosthetic hip infection-related and unrelated deaths. RESULTS One hundred and fifty-seven patients with periprosthetic hip infections with a median infection duration of 258 days (interquartile range, 120 to 551 days) prior to our index surgical procedure for infection were included. Periprosthetic hip infection occurred in ninety-nine cases of primary hip arthroplasty, twenty-seven cases of revision arthroplasty, and thirty-one cases in which the periprosthetic hip infection had been treated previously. A difficult-to-treat organism was isolated in fifty-nine cases (38%). After a median follow-up of 41.6 months (interquartile range, 28.1 to 66.9 months), two relapses, six new infections, nine revisions for mechanical reasons, two related deaths, and nineteen unrelated deaths occurred. CONCLUSIONS One-stage exchange arthroplasty is an effective surgical procedure in patients with periprosthetic hip infection who have good bone quality. Precise identification of the microorganism(s) and prolonged administration of appropriate intravenous antibiotic therapy are key factors for successful treatment.

Influence of posterior condylar offset on knee flexion after cruciate-sacrificing mobile-bearing total knee replacement: a prospective analysis of 410 consecutive cases.

The range of motion of the knee joint after Total Knee Replacement (TKR) is a factor of great importance that determines the postoperative function of patients. Much enthusiasm has been recently directed towards the posterior condylar offset with some authors reporting increasing postoperative knee flexion with increasing posterior condylar offset and others who did not report any significant association. Patients undergoing primary total knee replacement were included in a prospective multicentre study and the effect of the posterior condylar offset on the postoperative knee flexion was assessed after adjusting for known influential factors. All knees were implanted by three senior orthopedist surgeons with the same cemented cruciate-sacrificing mobile-bearing implant and with identical surgical technique. Clinical data, active knee flexion and posterior condylar offset were recorded preoperatively and postoperatively at a minimal one year follow-up for all patients. Univariate and multivariate linear models were fitted to select independent predictors of the postoperative knee flexion. Four hundred and ten consecutive total knee replacements (379 patients) were included in the study. The mean preoperative knee flexion was 112°. The mean condylar offset was 28.3mm preoperatively and 29.4mm postoperatively. The mean postoperative knee flexion was 108°. No correlation was found between the posterior condylar offset or the tibial slope and the postoperative knee flexion. The most significant predictive factor for postoperative flexion after posterior-stabilized TKR without PCL retention was the preoperative range of flexion, with a linear effect.

P Value and the Theory of Hypothesis Testing: An Explanation for New Researchers

In the 1920s, Ronald Fisher developed the theory behind the p value and Jerzy Neyman and Egon Pearson developed the theory of hypothesis testing. These distinct theories have provided researchers important quantitative tools to confirm or refute their hypotheses. The p value is the probability to obtain an effect equal to or more extreme than the one observed presuming the null hypothesis of no effect is true; it gives researchers a measure of the strength of evidence against the null hypothesis. As commonly used, investigators will select a threshold p value below which they will reject the null hypothesis. The theory of hypothesis testing allows researchers to reject a null hypothesis in favor of an alternative hypothesis of some effect. As commonly used, investigators choose Type I error (rejecting the null hypothesis when it is true) and Type II error (accepting the null hypothesis when it is false) levels and determine some critical region. If the test statistic falls into that critical region, the null hypothesis is rejected in favor of the alternative hypothesis. Despite similarities between the two, the p value and the theory of hypothesis testing are different theories that often are misunderstood and confused, leading researchers to improper conclusions. Perhaps the most common misconception is to consider the p value as the probability that the null hypothesis is true rather than the probability of obtaining the difference observed, or one that is more extreme, considering the null is true. Another concern is the risk that an important proportion of statistically significant results are falsely significant. Researchers should have a minimum understanding of these two theories so that they are better able to plan, conduct, interpret, and report scientific experiments.

How soon can I be proficient in embryo transfer? Lessons from the cumulative summation test for learning curve (LC-CUSUM)

BACKGROUND Embryo transfer, a crucial step for achieving pregnancy after in vitro fertilization, is an operator-dependent technique but the number of procedures required for a trainee to reach proficiency is unknown. We set out to evaluate the learning curve (LC) of embryo transfer using a specifically designed statistical tool. METHODS The first embryo transfers performed by five trainees were monitored by the cumulative summation test for learning curve (LC-CUSUM), a statistical tool designed to indicate when a process has reached a predefined level of performance. The main outcome measure was a positive hCG test. A 40% pregnancy rate (PR) per transfer was chosen to define adequate performance and a PR of 20% was considered inadequate. After the learning phase, standard CUSUM were implemented to ensure that performance was maintained. The same CUSUM parameters were also applied to monitor 241 consecutive embryo transfers performed by a senior gynaecologist. RESULTS Between 11 and 99 embryo transfers were necessary for the trainees to reach the predefined level of performance. Simple and intuitive graphical representations of the LCs were generated. CUSUM tests confirmed that performance was maintained after the learning phase. The PR of the senior gynaecologist was 42.7% and the CUSUM showed that performance remained adequate throughout the 241 procedures. CONCLUSIONS This study provides an exportable model for a quantitative monitoring of the LC of embryo transfer as well as a reference curve for continuous monitoring of performance in embryo transfer. The length of the LC of embryo transfer is highly variable, justifying a tailored training to learn this procedure.

The account for provider and center effects in multicenter interventional and surgical randomized controlled trials is in need of improvement: a review.

OBJECTIVE To systematically review the account of center and provider effects in large surgical and interventional randomized controlled trials. STUDY DESIGN A systematic review of multicenter interventional randomized trials of 200+ patients. The search included Medline from 1 January 2000 through 11 October 2005 and a hand search of the bibliographies of retrieved articles. One author abstracted all data using standardized abstraction forms; a second reviewer assessed a random sample of reports as quality-assurance procedure. RESULTS Sixty-eight reports met inclusion criteria. The trials predominantly reported on cardiology (n=23, 34%). The number of participating providers was reported in 11 trials (16%). Both the performed control and performed interventional procedures were described in 43 trials (63%). The use of stratified random allocation on center was reported in 26 trials (38%) and on provider in 6 trials (9%). The analysis was adjusted for center in four trials (6%) and for provider in three trials (4%). CONCLUSIONS Only few trials account for center or provider effect in the design and analysis. Authors and journal editors could play an important role in improving the reporting of trials.

Outcome of group B streptococcal prosthetic hip infections compared to that of other bacterial infections

BACKGROUND Outcome of streptococcal prosthetic hip infection is often thought to be better than that caused by other pathogens. That supposition was not confirmed in our experience with group B streptococcal prosthetic joint infection. OBJECTIVE We compared outcomes of group B streptococcal and other-pathogen prosthetic hip infections. METHODS One hundred and thirty nine patients, 24 with group B streptococcal and 115 other-pathogen prosthetic hip infections, were included. The primary outcome was the time from surgical treatment to treatment failure, defined as relapse, infection- or treatment-related death. Secondary outcomes were the times from surgical treatment to relapse or any event (event-free survival). The cumulative incidence estimator was used to model primary and secondary outcomes. Multivariable regression analysis was used to determine a set of independent predictors of treatment failure. RESULTS With a median follow-up of 22 months, treatment failed more frequently in patients with group B streptococcal prosthetic hip infections (hazard ratio, 4.88 [95% CI, 1.4-17], P=.012). Multivariable analysis retained the American Society of Anesthesiologist score and group B streptococcal infection as independent risk factors of treatment failure; event-free survival was lower for these patients (hazard ratio, 2.64 [95% CI, 1.2-6], P=.02). CONCLUSION Despite high antibiotic susceptibility, outcomes of group B streptococcal and other-pathogen prosthetic hip infection differ.

Fixation of pathological humeral fractures by the cemented plate technique

Pathological fractures of the humerus are associated with pain, morbidity, loss of function and a diminished quality of life. We report our experience of stabilising these fractures using polymethylmethacrylate and non-locking plates. We undertook a retrospective review over 20 years of patients treated at a tertiary musculoskeletal oncology centre. Those who had undergone surgery for an impending or completed pathological humeral fracture with a diagnosis of metastatic disease or myeloma were identified from our database. There were 63 patients (43 men, 20 women) in the series with a mean age of 63 years (39 to 87). All had undergone intralesional curettage of the tumour followed by fixation with intramedullary polymethylmethacrylate and plating. Complications occurred in 14 patients (22.2%) and seven (11.1%) required re-operation. At the latest follow-up, 47 patients (74.6%) were deceased and 16 (25.4%) were living with a mean follow-up of 75 months (1 to 184). A total of 54 (86%) patients had no or mild pain and 50 (80%) required no or minimal assistance with activities of daily living. Of the 16 living patients none had pain and all could perform activities of daily living without assistance. Intralesional resection of the tumour, filling of the cavity with cement, and plate stabilisation of the pathological fracture gives immediate rigidity and allows an early return of function without the need for bony union. The patients local disease burden is reduced, which may alleviate tumour-related pain and slow the progression of the disease. The cemented-plate technique provides a reliable option for the treatment of pathological fractures of the humerus.

Monitoring surgical performance: an application to total hip replacement

RATIONALE, AIMS AND OBJECTIVES Inadequate surgical implantation of a hip replacement may result in decreased patient satisfaction and reduced implant survival. The objective was to monitor surgical performance in hip replacement. METHOD The study took place at a teaching centre. All primary total hip replacements were prospectively included in the series. For each hip replacement, intraoperative technical errors, cup and stem fixation and position, and postoperative complications were recorded. If all items rated were correct, the procedure was considered as correct. The Cumulative Sums (CUSUM) test was used to monitor the performance of the centre. A 90% proportion of successful procedures was considered as adequate performance and a 75% proportion of successful procedures was deemed as inadequate performance. Meetings were conducted to discuss the results of monitoring. RESULTS Eighty-three total hip replacements were monitored. Overall, 28 procedures (34%) were considered inadequate. The most potent reasons for inadequate performance were cup positioning and stem fixation. The CUSUM test signalled after the second procedure that performance was inadequate. After the first meeting, despite an improvement was seen, the CUSUM test raised an alarm indicating inadequate performance. The study was stopped after the second meeting because of funding reasons before it could be demonstrated that performance had reached the desired level. CONCLUSION This study has demonstrated that implementing a dedicated system to monitor surgical performance in a teaching hospital improves the quality of implantation of total hip replacements. Nonetheless, the target of ninety percent of adequate primary total hip replacement could not be reached and efforts should be continued.

Axial Skeletal Location Predicts Poor Outcome in Ewing's Sarcoma: A Single Institution Experience

Introduction. Ewings sarcomas (EWSs) of bone and soft tissue are neuroectodermal tumors that affect both axial and appendicular locations. We hypothesized that axial location predicted poor outcome in EWS patients. Materials and Methods. Sixty-seven patients (57 with bone EWS and 10 with soft tissue EWS) were identified from our database. Thirty-four (51%) had axial EWS and 33 (49%) had appendicular EWS. Statistical analyses identified predictors of poor outcome. Results and Discussion. Axial location, large size, metastases at presentation, lack of definitive treatment, and positive surgical margins all correlated with poor outcome in univariate analysis. In multivariate analysis, axial location still predicted poor outcome when adjusted for pretreatment variables. Axial location was not statistically predictive of poor outcome when adjusted for treatment variables. Conclusions. Anatomic location has a negative effect on outcome in EWS that cannot be completely explained by pretreatment or treatment factors. Additional studies are required to determine if there is a biologic difference between axial and appendicular EWS.