Surgical trial design - learning curve and surgeon volume: Determining whether inferior results are due to the procedure itself, or delivery of the procedure by the surgeon

Learning Sensory Nerve Coaptation in Free Flap Breast Reconstruction

BACKGROUND

 The aims of this study were to assess whether sensory nerve coaptation in free flap breast reconstruction is subject to learning, and to elucidate challenges of this technique.

METHODS

 In this single-center retrospective cohort study, we reviewed consecutive free flap breast reconstructions performed between March 2015 and August 2018. Data were extracted from medical records, and missing values were imputed. We assessed learning by exploring associations between case number and probability of successful nerve coaptation using a multivariable mixed-effects model. Sensitivity analysis was performed in a subgroup of cases with evidence of attempted coaptation. Recorded reasons for failed coaptation attempts were grouped into thematic categories. Multivariable mixed-effects models were used to examine associations between case number and postoperative mechanical detection threshold.

RESULTS

 Nerve coaptation was completed in 250 of 564 (44%) included breast reconstructions. Success rates varied considerably between surgeons (range 21-78%). In the total sample, the adjusted odds of successful nerve coaptation increased 1.03-fold for every unit increase in case number (95% confidence interval 1.01-1.05, p < 0.05), but sensitivity analysis refuted this apparent learning effect (adjusted odds ratio 1.00, 95% confidence interval 1.00-1.01, p = 0.34). The most frequently recorded reasons for failed nerve coaptation attempts were inability to locate a donor or recipient nerve. Postoperative mechanical detection thresholds showed a negligible, positive association with case number (estimate 0.00, 95% confidence interval 0.00-0.01, p < 0.05).

CONCLUSION

 This study does not provide evidence in support of a learning process for nerve coaptation in free flap breast reconstruction. Nevertheless, the identified technical challenges suggest that surgeons may benefit from training visual search skills, familiarizing with relevant anatomy, and practicing techniques for achieving tensionless coaptation. This study complements prior studies exploring therapeutic benefit of nerve coaptation by addressing technical feasibility.

Explanatory and pragmatic trials in orthopaedics - Have we done the right studies?

Recent decades have seen marked advances in the quality of clinical orthopaedic trauma research, and with this has come a rise in the number of randomised clinical trials (RCTs) being conducted in orthopaedic trauma. These trials have been largely valuable in driving evidence-based management of injuries which previously had clinical equipoise. However, though RCTs are traditionally seen as the 'gold standard' of high-quality research, this research method is comprised primarily of two entities, explanatory and pragmatic designs, each with its own strengths and limitations. Most orthopaedic trials lie within a continuum between these designs, with varying degrees of both pragmatic and explanatory features. In this narrative review we provide a summary of the nuances within orthopaedic trial design, the advantages and limitations of such designs, and suggest tools which may aid clinicians in the appropriate selection and evaluation of trial designs.

Decision-making in surgical study designs: a proposed decision algorithm to aid in the selection of an appropriate research study design for a given surgical intervention: the PERFECT tool

Cite this article: Bone Joint Res  2023;12(9):598–600.

Comparative Learning Curves of Microscope Versus Exoscope: A Preclinical Randomized Crossover Noninferiority Study

Background

An exoscope heralds a new era of optics in surgery. However, there is limited quantitative evidence describing and comparing the learning curve.

Objectives

This study aimed to investigate the learning curve, plateau, and rate of novice surgeons using an Olympus ORBEYE exoscope compared to an operating microscope (Carl Zeiss OPMI PENTERO or KINEVO 900).

Methods

A preclinical, randomized, crossover, noninferiority trial assessed the performance of seventeen novice and seven expert surgeons completing the microsurgical grape dissection task “Star’s the limit.” A standardized star was drawn on a grape using a stencil with a 5 mm edge length. Participants cut the star and peeled the star-shaped skin off the grape with microscissors and forceps while minimizing damage to the grape flesh. Participants repeated the task 20 times consecutively for each optical device. Learning was assessed using model functions such as the Weibull function, and the cognitive workload was assessed with the NASA Task Load Index (NASA-TLX).

Results

Seventeen novice (male:female 12:5; median years of training 0.4 [0–2.8 years]) and six expert (male:female 4:2; median years of training 10 [8.9–24 years]) surgeons were recruited. “Star’s the limit” was validated using a performance score that gave a threshold of expert performance of 70 (0–100). The learning rate (ORBEYE −0.94 ± 0.37; microscope −1.30 ± 0.46) and learning plateau (ORBEYE 64.89 ± 8.81; microscope 65.93 ± 9.44) of the ORBEYE were significantly noninferior compared to those of the microscope group (p = 0.009; p = 0.027, respectively). The cognitive workload on NASA-TLX was higher for the ORBEYE. Novices preferred the freedom of movement and ergonomics of the ORBEYE but preferred the visualization of the microscope.

Conclusions

This is the first study to quantify the ORBEYE learning curve and the first randomized controlled trial to compare the ORBEYE learning curve to that of the microscope. The plateau performance and learning rate of the ORBEYE are significantly noninferior to those of the microscope in a preclinical grape dissection task. This study also supports the ergonomics of the ORBEYE as reported in preliminary observational studies and highlights visualization as a focus for further development.

Direction- and Angle-Assisted Buttonhole Cannulation of Arteriovenous Fistula in Hemodialysis Patients: A Multicenter Randomized Controlled Trial

RATIONALE & OBJECTIVE

Arteriovenous fistula cannulation with the buttonhole technique is often preferred by patients but has been associated with an increased infection risk. Guidelines disagree on whether it should be abandoned, thus we assessed a technologically simple method to facilitate gentler arteriovenous fistula cannulation with potentially less discomfort and damage to the epithelial lining of the buttonhole tract.

STUDY DESIGN

8-week, prospective, open-label, randomized controlled trial.

SETTING & PARTICIPANTS

Patients with buttonhole tracts receiving hemodialysis at 7 dialysis centers in Norway were randomized to the intervention group (43 patients, 658 cannulations) or control group (40 patients, 611 cannulations).

INTERVENTION

Direction and angle of the established buttonhole tract were marked on the forearm skin in the intervention group, whereas the control group had no structured cannulation information system.

OUTCOMES

The primary outcome was successful cannulation, defined as correct placement of both blunt needles at the first attempt without needing to change needles, perform extra perforations, or reposition the needle. The secondary outcomes were patient-reported difficulty of cannulation (verbal rating scale: 1 = very easy, 6 = impossible) and intensity of pain (numeric rating scale: 0 = no pain, 10 = unbearable pain).

RESULTS

After a 2-week run-in period, successful cannulation was achieved in 73.9% and 74.8% of the patients in the intervention and control groups, respectively (relative risk [RR], 0.99; 95% CI, 0.87-1.12; P = 0.85). However, the probability of a difficult arterial cannulation (verbal rating scale, 3-6) was significantly lower in the intervention group (RR, 0.69; 95% CI, 0.55-0.85; P = 0.001). There were no improvements for venous cannulations. Furthermore, the probability of a painful cannulation (numeric rating scale, 3-10) was lower in the intervention group (RR, 0.72; 95% CI, 0.51-1.02; P = 0.06).

LIMITATIONS

Unable to evaluate hard end points such as infections and thrombosis owing to the small sample size.

CONCLUSIONS

Marking direction and angle of cannulation did not improve cannulation success rates; however, patients more often reported an unproblematic procedure and less pain.

FUNDING

None.

TRIAL REGISTRATION

ClinicalTrials.gov (NCT01536548).

[Learning curves in acquisition of experience for new technologies]

OBJECTIVE

Analysis of national and foreign trials investigating accumulation of experience in innovative technologies using the learning curves.

MATERIAL AND METHODS. S

Earching for Russian-language manuscripts was carried out within the references of the articles and in the ELIBRARY database. Foreign trials were selected from the PubMed database according to the keywords «learning curves in surgical practice». The discovered publications were studied for accordance with the objectives of this study.

RESULTS

Accumulation of experience in new technologies by using of learning curves is valuable to improve the training, determine duration of development of new technology and the factors affecting its characteristics.

CONCLUSION

The method is high-quality for comprehensive analysis of experience accumulation in new surgical technologies.

Screw configuration in proximal humerus plating has a significant impact on fixation failure risk predicted by finite element models

BACKGROUND

Proximal humeral fractures occur frequently, with fixed angle locking plates often being used for their treatment. No current quantitative evidence for the effect of different screw configurations exists, and the large number of variations makes biomechanical testing prohibitive. Therefore, we used an established and validated finite element osteosynthesis test kit to quantify the effect of variations in screw configuration on predicted failure risk of PHILOS plate fixation for unstable proximal humerus fractures.

METHODS

Twenty-six low-density humerus models were osteotomized to create malreduced unstable 3-part fractures that were virtually fixed with PHILOS plates. Twelve screw configurations were simulated: 6 using 2 screw rows, 4 using 3 rows, and 1 with either 8 or 9 screws. Three physiological loading cases were modeled and an established finite element analysis methodology was used. The average peri-screw bone strain, previously demonstrated to predict fatigue cutout failure, was used to compare the different configurations.

RESULTS

Significant differences in peri-screw strains, and thus predicted failure risk, were seen with different combinations. The 9-screw configuration demonstrated the lowest peri-screw strains. Fewer screw constructs showed lower strains when placed further apart. The calcar screws (row E) significantly (P < .001) reduced fixation failure risk.

CONCLUSION

Screw configurations significantly impact predicted cutout failure risk for locking plate fixations of unstable proximal humerus fractures in low-density bone. Although requiring clinical corroboration, the result of this study suggests that additional screws reduce peri-screw strains, the distance between them should be maximized whenever possible and the calcar screws should be used.

The influence of screw length on predicted cut-out failures for proximal humeral fracture fixations predicted by finite element simulations

BACKGROUND

The aim of this study was to identify the effect of screw length on predictions of fixation failure in three-part proximal humeral fractures using a finite element-based osteosynthesis modelling toolkit.

METHODS

A mal-reduced unstable three-part AO/OTA 11-B3.2 fracture with medial comminution was simulated in forty-two digitally processed proximal humeri covering a spectrum of bone densities and fixed with the PHILOS plate using three distal and six proximal locking screws. Four test groups were generated based on the screw tip to joint surface distance (TJD), with all proximal screws being shortened from 4 mm TJD to be 8, 12 or 16 mm TJD. Average bone strains around the screw tips, correlating with biomechanical cyclic cut-out-type failure, were evaluated in three physiological loading protocols representing simple shoulder motions. Six further groups were tested, where five of the proximal screws were inserted to 4 mm TJD and the sixth screw to 8 mm TJD.

RESULTS

Exponential increases in the predicted risk of fixation failure were seen with increased tip-to-joint distances (p < 0.001). When one of the proximal screws was placed 8 mm from the joint, with the remaining five at 4 mm distance, significant increases (p < 0.001) were registered in the strains around the screw tips in all except the two superior screws. This effect was maximal around the calcar screws (p < 0.001) and for lower density samples (p < 0.001).

CONCLUSIONS

These results suggest that longer screws provide reduced risk of cut-out failure, i.e. distalisation and/or varisation of the head fragment, and thus may decrease failure rates in proximal humeral fractures treated with angular stable plates. These findings require clinical corroboration and further studies to investigate the risk of screw perforation.

Perioperative Safety: Keeping Our Children Safe in the Operating Room

The entire operating room team is responsible for the safety of children in the operating room. As a leader in the operating room, the surgeon is impactful in ensuring that all team members are committed to providing this safe environment. This is achieved by the use of perioperative huddles or briefings, the use of appropriate surgical checklists, operating room standardization, surgeons proficient in the care they provide, and team members that embrace Just Culture.

Prediction of the learning curves of 2 dental CAD software programs

STATEMENT OF PROBLEM

Dental clinical procedures are being replaced by digital workflows. Therefore, the time necessary to learn dental computer-aided design (CAD) software to achieve a change in the digital workflow should be evaluated.

PURPOSE

The purpose of this study was to predict the learning curve according to the type of dental CAD software with the Wright model and to determine the rate of improvement in the learner's working time with iterative learning.

MATERIAL AND METHODS

A total of 40 participants with various degrees of experience with dental computer-aided design and computer-aided manufacturing (CAD-CAM) systems were recruited. The 4 specified steps of a custom abutment design were performed with 3DSystem CAD software (Daesung) and exocad DentalCAD (exocad GmbH) software and were repeated 3 times in stages. The times were analyzed with repeated-measures 1-factor and 2-factor analyses. The learning time for 300 design iterations was estimated by applying the Wright model formula, and the 300-repetition times were analyzed with the Mann-Whitney U test (α=.05).

RESULTS

exocad had a longer mean learning time than the 3DSystem. The overall change with repeated learning was significantly different (P<.001), and all differences were found in the first to third iterations. Software-dependent differences were also observed (P=.005). The Mann-Whitney U test also revealed a significant difference between the 2 software programs (P=.015), but no significant difference was found after the 56th iteration (57th iteration: P=.051).

CONCLUSIONS

As the time reduction patterns for iterative learning differ depending on the type of CAD software, the learning curves may differ according to the type of software. As the operator's skill increased through iterative learning, the differences in learning times between the software programs gradually disappeared.

Learning curve with a new primary total knee arthroplasty implant: a multicenter perspective with more than 2000 patients

Background

This study provides an example for evaluating learning curve when introducing a new knee system.

Methods

Thirty-five investigators across 22 sites prospectively implanted 843 subjects with currently available products (group A). Seventy-seven investigators across 48 sites prospectively implanted 2330 subjects with the ATTUNE Knee System; in which the first 10 subjects for each surgeon were the learning curve cases (group B, N = 611), and the later subjects were designated as group C (N = 1719). Surgical time, rates of intraoperative and early postoperative complications, and patient-reported outcome measures (PROMs) at a minimum of 1 year were compared.

Results

Mean (standard deviation) surgical time was 72.0 (21.6) minutes for group A, 83.0 (24.2) for group B, and 72.1 (24.1) for group C (P < .001 for group B vs group C; P = .955 for group C vs group A). Intraoperative, early (<90 day) complication rates, and PROMs were similar for all groups.

Conclusions

The new knee system learning curve was characterized by a slightly longer surgical time with no negative impact on complications or PROMs.

Level of Evidence

III.

Exploring and adjusting for potential learning effects in ROLARR: a randomised controlled trial comparing robotic-assisted vs. standard laparoscopic surgery for rectal cancer resection

Background

Commonly in surgical randomised controlled trials (RCT) the experimental treatment is a relatively new technique which the surgeons may still be learning, while the control is a well-established standard. This can lead to biased comparisons between treatments. In this paper we discuss the implementation of approaches for addressing this issue in the ROLARR trial, and points of consideration for future surgical trials.

Methods

ROLARR was an international, randomised, parallel-group trial comparing robotic vs. laparoscopic surgery for the curative treatment of rectal cancer. The primary endpoint was conversion to open surgery (binary). A surgeon inclusion criterion mandating a minimum level of experience in each technique was incorporated. Additionally, surgeon self-reported data were collected periodically throughout the trial to capture the level of experience of every participating surgeon.

Multi-level logistic regression adjusting for operating surgeon as a random effect is used to estimate the odds ratio for conversion to open surgery between the treatment groups. We present and contrast the results from the primary analysis, which did not account for learning effects, and a sensitivity analysis which did.

Results

The primary analysis yields an estimated odds ratio (robotic/laparoscopic) of 0.614 (95% CI 0.311, 1.211; p = 0.16), providing insufficient evidence to conclude superiority of robotic surgery compared to laparoscopic in terms of the risk of conversion to open.

The sensitivity analysis reveals that while participating surgeons in ROLARR were expert at laparoscopic surgery, some, if not all, were still learning robotic surgery. The treatment-effect odds ratio decreases by a factor of 0.341 (95% CI 0.121, 0.960; p = 0.042) per unit increase in log-number of previous robotic operations performed by the operating surgeon. The odds ratio for a patient whose operating surgeon has the mean experience level in ROLARR – 152.46 previous laparoscopic, 67.93 previous robotic operations – is 0.40 (95% CI 0.168, 0.953; p = 0.039).

Conclusions

In this paper we have demonstrated the implementation of approaches for accounting for learning in a practical example of a surgery RCT analysis. The results demonstrate the value of implementing such approaches, since we have shown that without them the ROLARR analysis would indeed have been confounded by the learning effects.

Trial registration

International Standard Randomised Controlled Trial Number (ISRCTN) registry, ID: ISRCTN80500123. Registered on 27 May 2010.

Influence of 2D vs 3D imaging and professional experience on dental implant treatment planning

OBJECTIVES

This study investigated whether professional experience and type of image examination (panoramic radiography (PAN) or cone beam computed tomography (CBCT)) could influence the pre-surgical planning for dental implant treatment.

MATERIALS AND METHODS

Six dentists, from two different levels of experience (senior (Sr) and junior (Jr)) performed simulated pre-surgical planning by using PANs and after 1 month, by using CBCTs, considering implant length (IL), implant width (IW), need for bone graft (BG), and other surgical procedures (OP). Bland-Altman test and Kappa coefficient were used to identify agreements.

RESULTS

Bland-Altman test showed good agreement in the plans for inter-professional (i.e., Sr vs Jr) comparisons. Bland-Altman plots displayed intra-observer agreement (i.e., differences between PAN and CBCT), showing discrepancy between imaging modalities for IL and a tendency towards selecting larger dental implant options when using PAN and smaller options with CBCT. Kappa showed almost perfect (0.81-1.0) agreement between Jr and Sr for OP (PAN and CBCT). For BG, agreement was substantial (0.61-0.80) when planning was done with PAN and CBCT. Descriptive statistics showed evidence that when Jrs used CBCT, they no longer indicated the BG they had planned when they used PAN.

CONCLUSION

There were differences in the pre-surgical planning for treatment with dental implants depending on the professional experience and the type of imaging examination used.

CLINICAL RELEVANCE

Variation in dental implant planning can affect treatment time, cost, and morbidity in patients.