Manual Dexterity Training for Orthopaedic Residents - Non-Patient based Methodologies

Background: Orthopaedic surgical techniques are complex, rapidly evolving, and require significant training to attain competence. Hindrances to acquiring these complex skills during residency include: work hour restrictions, inconsistent case volumes, and policy changes centered on operating room (OR) efficiency and patient safety. The evolution of orthopaedic training in response to these challenges forced the development of non-patient-based training methods outside of the OR. Understanding how orthopaedic residents develop and retain surgical skills will hopefully provide more efficient training. The different methods, their respective advantages, and evidence of their efficacy is necessary to direct resident training in the future. Methods: PubMed and Google Scholar were searched for literature related to orthopaedic resident training. The resulting articles were used to find other manuscripts pertinent to the subject. Training methods involving patients were excluded. Results: Non-patient-based methods for orthopaedic resident surgical training include cognitive training for knowledge acquisition, low fidelity models for basic skills, bench-top models for arthroscopic skill development, cadaveric and animal models, synthetic bone models, and virtual reality simulators. Evidence for the type of training resulting in the most robust skills acquisition and retention, supports targeted, deliberate practice in spaced repetitions using a competency-based curriculum. Conclusion: A variety of non-patient based methods exist for surgical skill development, aimed at mitigating challenges faced by orthopaedic residents. Despite their abundance, evidence supporting direct transfer of skills learned via these methods to the OR is rare in orthopedics. Barriers to their use and implementation, namely a lack of funding, are prevalent.


How residents learn: maximizing efficiency and transferrable surgical skill acquisition
Orthopaedic procedures require considerable psychomotor skill and knowledge, both concerning the procedure and pathoanatomy, in order to prevent iatrogenic injury to the patient [11,12]. Minimally invasive procedures such as arthroscopy present additional challenges such as the fulcrum effect, handeye coordination for triangulation, and visual-spatial coordination to construct 2-dimensional images into 3-dimensions [11,13].

The acquisition of orthopaedic surgical skills is exemplified by
Fitts and Posner's three-stage theory of motor skill acquisition [6,14,15]. According to Fitts and Posner, there are 3 overlapping but progressive stages in the learning of any motor skill: cognition, integration, and automation ( Figure 1) [16]. In the cognitive stage, performance is erratically non-fluid as the trainees attempt to intellectualize the task and understand the mechanics of the skill. In the integrative stage, the trainee is still gaining fluidity and efficiency, but still actively thinking about how to translate their knowledge into the appropriate motor movements. Once the automation stage is reached, execution of the task is precise, efficient, reflexive, allowing incorporation of other aspects of the procedure into their actions and decision making. Progression to each stage is mediated by external instruction, repeated practice, feedback, self-reflective audit, and confidence.

Figure 1:
Fitts and Posner believed that a power function relating practice to performance could be demonstrated as learners advanced through three overlapping, progressive stages of motor skill development. In the first stage (cognitive) the learner's performance is erratic and stepwise as they attempt to intellectualize what they are supposed to do. Repetition and feedback allow progression to the second stage (integration). During the integrative stage, where knowledge gained in the cognitive stage is translated into movement, the learner gains fluidity and consistency. In the autonomous stage, the learner no longer actively thinks about the movements; they are efficient and precise, allowing the learner to focus on other aspects.
The type of practice for orthopaedic trainees matters.
Deliberate practice with spaced repetition and feedback in a structured training format shows more robust retention (defined as durability of skill acquisition at one-month retesting) and greater transfer of skills to more realistic settings in surgical residents [17,18]. Deliberate practice also engages trainees in progressively challenging tasks, with immediate feedback on their performance, and the opportunity to improve by repeating the same or similar task, thereby correcting errors [19]. The purpose of this review is to provide an overview of nonpatient based training methodologies for orthopaedic residents.
The rationale for their use, as well as some of their proposed shortcomings, will be discussed.

Cognitive training tools to enhance knowledge
The development of orthopaedic surgical skill is a complex relationship based upon interaction between the cognitive (knowledge based) domain and the psychomotor (technical skill) domains [25]. Cognitive improvements such as anatomical understanding, tools used, individual steps of a procedure, and how each step is performed, may reduce the overall training time required to reach technical competence by giving meaning to the skills being practiced [26,27]. Knowledge acquisition and retention in medical education can be enhanced by engaging trainees in active learning methods in addition to standard passive learning such as didactic teaching or textbook reading [28]. Studies based on adult learning theories have shown that the learning curve of active learning is higher than that of passive learning [29].
E-learning is one way educators are attempting to maximize orthopedic resident knowledge while minimizing costs and instructor time commitment [30]. E-learning is internet and computer-based multimedia instruction with the ability to be accessed remotely and at any time (Table 1). Content can range from interactive online modules containing videos, radiographic images, and text to virtual reality environments and virtual patients [31]. Cook et al. [32] performed a 2010 meta-analysis on E-learning as an instructional tool for potential health professionals (students, residents, fellows, and practitioners) and found improved learning outcomes were significant when E-learning had the following characteristics: interactive elements, repetition of study materials, practice exercises/assessments, and feedback [32]. Commercially produced, comprehensive, web-based learning modules specifically designed for orthopaedic residents have already been produced, such as the ortho bullets PASS Curriculum (Lineage Medical, Santa Barbara, CA, USA). The PASS Curriculum, aimed at providing orthopedic residents with the knowledge and skills to be successful on the orthopedics In-Training Examination, was found to produce significant increases in resident scores and had a high level of resident satisfaction [33]. E-learning has the advantage of rapid updateability; new modules can be added, different surgeries and scenarios can be taught, and learning can be monitored by assessments in the module [34]. There have been several E-learning modules produced and tested for orthopedic resident education. Hearty et al. found that resident instruction via an E-learning training module was more effective than simply reading textbooks in preparation for an actual closed reduction and pinning of pediatric supracondylar fracture based on multiple choice question testing and subjective feedback from the attending surgeons after the case [30]. The residents selfreported greater confidence, with less anxiety in the OR after the module, however, objective measures of surgical performance were not evaluated. Another E-learning module has been developed and tested on orthopaedic residents that walks the trainee through the steps of a simulated hip fracture repair [35,36]. It allows the trainee to click through relevant steps, and make decisions about specific aspects of the procedure. Importantly, the module was able to discriminate between surgical experience, by measuring and providing feedback on incision length, final screw placement, misplaced drill-holes, reduction position, the number of radiographs taken, and the total surgical time to completion. Similar E-learning modules have been developed to teach orthopedic trainees pedicle and sacroiliac screw insertion, with the added advantage that patient specific imaging data can be used in the module [37,38].
While E-learning has been accepted by medical student educators as a useful tool for teaching theoretical knowledge, we were unable to find any study demonstrating improved orthopaedic surgical performance with its use [39][40][41][42]. E-learning does have its shortcomings and cannot completely replace face to face education.
It is merely a tool to augment the interactions between instructors and trainees [34]. The effectiveness of E-learning is also affected by the content in the modules, requiring elements such as interactivity, evaluations, and feedback in order to be truly more effective than just reading a textbook [32].

Simulation
Simulation in medical education has emerged out of necessity. can mimic all the aspects of a real surgery [34].
Orthopaedic resident involvement in surgery has generally been associated with prolonged operative times in large scale analyses [43][44][45]. institutions comprising both teaching and non-teaching hospitals who underwent orthopaedic procedures [43]. These findings are confirmed by most studies [44][45][46][47][48] with the exception of one study finding increased complications when residents were present in joint arthroplasty cases [49]. However, these studies did not describe the level of intraoperative and perioperative involvement of the resident. One study found no difference in short term clinical outcomes in patients who underwent total hip arthroplasty performed by an attending surgeon compared to a resident under direct supervision of an attending [50].

Low fidelity models for basic skill acquisition
The general rule for simulation is that with higher fidelity comes higher cost [6]. Low fidelity models are the most economical of the simulators and can be effective tools in training if developed and used correctly [12]. By providing exposure to the instruments and basic fundamental steps of procedures, low fidelity simulator training can lay the foundation for progression through competencebased orthopaedic training. Because of the low costs, these training tools allow repetitive, deliberate practice of a particular skill distributed over an extended period of time. This has been shown to translate into better retention of the psychomotor skills due to long-term structural modifications in associated pathways in the brain [59].
Low fidelity tools designed for orthopaedic education include microsurgery fundamentals training using a latex glove, knot tying exercises on a knot tying board, and bone drilling on PVC pipes [60][61][62]. Surgical skills labs have been developed and implemented as part of PGY-1 competency-based curriculum that combine different models and simulated tasks with objective assessments [59,61].
Labs that implement progression from low fidelity to more realistic simulations upon demonstration of competency, have also been shown to be effective in increasing orthopaedic resident skills [62].
The advantage of basic skills training is that it allows for the component steps of complex surgeries to be segmented, allowing the learner to focus on developing cognitive and psychomotor skills 50. These skills require less attention as the trainee progresses through the integration and automation stages, as they practice in preparation for the actual surgery [54]. However, there are disadvantages to fragmenting a complex procedure into its simpler component parts. Studies found that if practice for a complex motor task such as bi-cortical bone plating using a fractured cadaver bone is broken down into separate component parts, trainees did not perform as well as those who practiced the whole task from start to finish, a concept termed "functional order practice" [63,64]. Explanations for these findings postulate the idea that

Benchtop models for arthroscopic skill acquisition
Arthroscopy requires a special skillset, involving dexterity, hand-eye coordination in a visual plane, and the ability to know and identify anatomy despite varying degrees of arthroscope offset [67].
Development of the basic motor skills required for arthroscopy such as visual-spatial perception, coordination, and familiarity with the fulcrum effect are benefitted more by factors like repetition and feedback compared to how realistic the simulator is [68]. With this in mind, several low cost arthroscopic simulators were developed that consisted of a trainer box with prefabricated ports, an optical system (arthroscope, light source, camera, and video monitor), and internal components that could be rapidly swapped out based on which skill was being simulated. Skills taught via these methods included arthroscopic knot tying, suture passing, probing, grasping, and triangulation (

Cadaver based simulation
Since its origins in the sixteenth century, surgical education using cadavers remains the most realistic simulation method [1].
Cadavers expose trainees to real anatomy and variations that can be encountered in patients ( Figure 3A & 3B). The ability to handle soft tissue and experience planes of dissection is something that no other simulation except for animal models can provide. However, the degree of fidelity depends on the condition of the cadaver (fresh versus embalmed, age of death, etc.) and the simulation design [72].
In support of this belief, Camp et al. [73] found that residents trained in diagnostic knee arthroscopy on a cadaver performed better than those who trained using a VR simulator, indicating disparity between the two simulations. Cadavers, however, have high costs associated with acquiring, preparing, and storing the specimens, making repetition impractical [21]. There is also the risk of disease transmission with fresh cadavers, as well as the disproportionate representation of the elderly population whose bone composition may differ from the general orthopedic patient population.

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Simulated open and arthroscopic procedures have been developed using cadavers as training and assessment tools. Van Heest et al. [74] developed an open carpal tunnel release simulation based on cadavers that showed demonstrable differences in OSATS score that correlated with surgeon experience, indicating construct validity. Construct validity in a simulator is determined by its ability to accurately measure the specific qualities that it was designed to measure. In this case it was to demonstrate differences between novices and experts in performance metrics. Furthermore, construct validity may highlight metrics or exercises relevant to becoming a competent surgeon [75].
Several studies with small subject populations have demonstrated rapid improvement in drilling and placement of thoracic pedicle screws using cadaver specimens [76,77]. In a study by Bergesen et al. [76] three orthopaedic residents were given didactic instruction by an expert surgeon and then allowed to place a total of 297 thoracic pedicle screws in 149 cadaver vertebrae (5 cadavers per resident). When the procedure was analyzed by an expert surgeon, the percentage of misplaced screws was reduced from 34% in the first cadaver to 15% in the final cadaver. In a similar study, Tortolani et al. [77] used computed tomography to evaluate placement of thoracic pedicle screws by 3 residents, who were trained using repeated attempts of screw placement on cadaver specimens. Trainees showed improvement in correct placement from 44% in the first cadaver to 58% in the final cadaver.
Arthroscopic training using cadaver models has also been shown to have construct validity by several studies. A 2015 study by Angelo et al. [78] showed significant performance differences between residents and experienced surgeons performing diagnostic arthroscopy with 3 suture anchor Bankart repair on cadavers [78].
The residents required more time for the procedure (45.5 versus 25.9 minutes) and made 50% more errors as assessed by blinded expert evaluators. These findings were similar to a previous study evaluating performance of a diagnostic knee [72]. Despite the ability for objective evaluation of arthroscopic performance using cadaver models to correlate with real world experience, the substantial overall costs associated with cadavers, as well as the rapid advances in VR technology, has led some groups to argue that VR based arthroscopic training may be a more effective training method based on cost-benefit analysis [73].

Animal models
Animal models as a method for surgical skill acquisition provides the benefit of allowing the trainee to handle real tissue, whose tactile properties are unaltered by formalin. Anesthetized, live animals can be used for training in vascular complications, such as bleeding [67]. However, animal models have similar drawbacks to cadavers due to ethical considerations, as well as the fact that most are not reusable, and the associated costs can be significant.
Simple training methods using animal parts, such as porcine joints and bones reduce the costs associated with keeping and anesthetizing live animals. A study by Leong et al. [2] comparing fracture fixation of porcine models to synthetic bone models for the assessment of technical skills showed that the porcine model was more sensitive for detecting differences in skill levels compared to the synthetic bone models [2]. These differences correlated with surgeon experience performing the procedure on patients.
More realistic, complicated simulations such as a microvascular training course using anesthetized rats have been developed [62].
Supplemented with non-living, low fidelity models and expert instruction, orthopedic residents were allowed to repeatedly perform end to end femoral artery anastomosis under microscopy on these rats. The femoral artery was chosen as the authors believed that it closely mimicked the human digital artery. At the end of the training, patency of the vessel was achieved in 11/12 orthopaedic residents involved compared to only 6/12 without the training. Additionally, Global Rating Scores improved significantly for the majority of trainees.

Synthetic bones
Composite bones have been a mainstay of orthopedic simulation due to their ability to mimic bone architecture and physical properties (Figure 4 & 5A) [79]. These bones can be purchased from multiple vendors and significantly more cost effective than cadaveric bones for teaching and understanding the biomechanics of real bones [80]. However, there are limitations to these replicas, as they do not completely emulate the viscoelastic properties, nor the internal architecture of real bone [81]. Composite bones have been used as tools for the development of a variety of orthopaedic skills such as fracture reduction, drilling, screw placement, fixation, and plating, as well as aspiration practice and arthroscopic skills ( Figure 5B & 5C) [82]. The relatively low cost, coupled with the ability to reuse the models, allows for spaced repetition and deliberate practice of skills resulting in enhanced long-term retention of skills [71,82].  Despite the potentially large initial cost of buying the interface and software, VR has several advantages over other methods of simulation. The machine can be used repeatedly, with minimal maintenance. In addition, all aspects of the simulation can be monitored and recorded, providing immediate feedback and tracking of progress [84]. Monitoring hand movements, operator efficiency, and accuracy is crucial to improving psychomotor training and reducing operating time. Arguably, the most exciting aspect of virtual reality simulation is the ability to combine patient specific MRI or CT data with haptic feedback [85]. This allows for exposure to anatomical variations between different patients, the ability face potential intra-operative difficulties that may arise, and pre-operative planning on how to best treat each patient.

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At the time of writing, we found 2 studies that directly showed transfer validity of a VR trainer for orthopedic residents performing in vivo diagnostic arthroscopy [53,56]. A 2014 randomized control, single blinded study by Cannon et al. [53] showing improved performance of orthopedic residents in diagnostic knee arthroscopy after interval training for an average of 11 hours on a high fidelity VR simulator [53]. The second and most recent evidence, comes from a 2016 randomized control, single blinded study by Waterman et al. [56] showing improved performance in diagnostic shoulder arthroscopy when orthopaedic residents trained on a high-fidelity VR trainer [56].
Multiple studies have investigated the ability of VR surgical simulators to distinguish between differing skill levels of the operator and objectively assess trainee skill progression. Two large systematic reviews of orthopaedic simulator training found that real world experience correlated with operator performance on arthroscopic simulators [11,12]. Despite studies demonstrating transfer of surgical skills acquired via laparoscopic VR training to the OR for non-orthopaedic residents, these systematic reviews found that there was a paucity of evidence that actually correlates simulator performance to performance in the OR specifically for orthopaedic procedures [86,87].

Areas for future research
A 2013 nationwide survey of orthopaedic residents and program directors by Karam et al. [58] showed widespread support for simulation in resident education [58]. Of the 687 orthopaedic residents and 86 program directors that responded, there was agreement that surgical simulation should be a mandatory part of the curriculum by 86% of residents and 80% of directors. However, only 76% of the program directors reported having dedicated surgical skills laboratories. Furthermore, only 46% of these programs with had a structured surgical skills curriculum, with a majority of respondents (87%) citing a lack of funding as the main barrier to creation and implementation.

Conclusion
Implementing new training methods will undoubtedly have increased costs and faculty time commitments, but these may be offset by increased return on investment [88]. Studies demonstrating return-on-investment for these new, alternative methods may persuade more administrations to invest in simulation. However, these studies are complex and orthopedic specific studies are rare [21]. The skills required to produce competent orthopaedic surgeons are a complex, inter-woven combination of physical and conceptual knowledge, translated into diagnostic and therapeutic ability. The latter, in particular, relies on manual dexterity and repetition under supervision. Investment at this 'ground-level' is crucial to propel this surgical specialty to higher levels in the future.