1 Introduction

Femoral shaft fractures (FSF) continue to represent a substantial clinical burden worldwide. Although incidence rates have declined in some regions, the absolute number of cases has risen, particularly among older adults, underscoring their persistent impact on health systems.¹ Intramedullary nailing remains the standard of care for FSF fixation, yet the consistency of trainee exposure may be constrained by contemporary training environments. This presents an educational challenge, as procedural volume is positively associated with improved patient outcomes and reduced complication rates.^2,3 Moreover, logistical, practical, and ethical constraints—such as duty-hour limits, pressure for operating room efficiency, and increasing emphasis on patient safety—further reduce opportunities for hands-on surgical training on patients.⁴

Variability in operative exposure is a relevant concern, since FSF management is considered a core competency for general orthopedic surgeons.⁵ The procedure is explicitly included in the trauma and orthopedic surgery curriculum of the British Intercollegiate Surgical Curriculum Programme,⁶ it is among the procedural milestones defined by the Accreditation Council for Graduate Medical Education in the US,⁷ and is a required competency to be performed independently in the Indian Master of Surgery Orthopaedics curriculum.⁸ In light of these mandates and considering the variability in training experiences, there is a need for a structured approach ensuring consistent acquisition of competences.

In response, competency-based medical education (CBME) has gained widespread traction.⁹ Rather than relying on time-based metrics, CBME emphasizes mastery of clearly defined competencies tailored to individual learning trajectories. Effective implementation of CBME depends on identifying relevant competencies and translating them into instructional and assessment strategies.¹⁰ This process aligns with Kern's six-step model for curriculum development, in which the first three steps involve problem identification, needs assessment, and specification of educational objectives.¹¹ Steps one and two were previously addressed in a national needs assessment by Gustafsson et al.,¹² which identified and prioritized key procedures for inclusion in a national simulation-based training curriculum. Among these, both basic osteosynthesis principles and FSF management were ranked as high priorities. However, step three, defining specific, measurable learning objectives for FSF, remains a gap in current curriculum development.

Simulation-based training (SBT) offers a promising platform for delivering procedural skills training within CBME frameworks.¹⁰ It enables repeated, structured practice in a risk-free environment until proficiency is acquired, but its feasibility and efficacy depend heavily on assessment and feedback —whether provided by instructors or embedded in a simulator.¹³ High-specificity feedback is a key driver of surgical skills acquisition, especially in settings where clinical exposure is limited. To support both simulation-based and clinical training, assessment must be grounded in tools with robust validity evidence, gathered in accordance with frameworks such as Messick's unified theory of validity.¹⁴ A foundational step in developing such assessment tools is the identification of procedure-specific assessment parameters that reflect expert consensus and can guide both feedback and formal evaluation.

The aim of this study was to establish expert consensus on assessment parameters for competency-based training and simulation-based evaluation of antegrade intramedullary nailing for simple femoral shaft fractures (AO/OTA 32A3. b).

2 Materials and methods

This modified Delphi study was conducted with an international panel of experts in orthopedic trauma surgery. It was administered entirely online using the SurveyMonkey platform and adhered to the Checklist for Reporting Results of Internet E-surveys (CHERRIES).¹⁵ Ethical approval was waived by the regional ethics committee of Zealand (EMN-2020-38838).

The Delphi method is a structured approach for reaching expert consensus through iterative rounds of anonymous feedback and is widely used in both curriculum development and assessment design.^16,17 Its multi-round structure allows panelists to revise their responses based on aggregated group input, thereby minimizing the influence of dominant individuals and promoting convergence toward consensus.¹⁸

The study was conducted between February and September 2021 and comprised four rounds. Each round was distributed via a personalized link to the survey. The present report focuses exclusively on antegrade intramedullary nailing of simple femoral shaft fractures (AO/OTA 32A3. b), which constituted one of seven procedures included in the survey. The other procedures were: tension band wiring, locking plate fixation, buttress plating, compression plating, bridge plating with position screws, and neutralization plating with lag screws. To minimize order effects, the sequence in which these procedures appeared was randomized for each panelist in Rounds 2 through 4. Results pertaining to locking plate fixation and compression plating have been published separately,^19,20 while findings for the remaining procedures are currently under review or in preparation. Survey deadlines ranged from 19 to 49 days, depending on survey length and vacation periods, with flexible intervals between rounds to accommodate data analysis.

3 Results

Of 355 invited experts, 119 accessed the survey link. Among these, six declined participation, four did not meet the inclusion criteria, and 11 provided no data. A total of 98 participants provided written consent and demographic information, resulting in a recruitment rate of 28 %. Eleven participants did not contribute any data across the four rounds but were still included in response rate calculations. A flowchart outlining the Delphi process is presented in Fig. 1. Characteristics and geographic distribution of the 87 actively participating panelists are shown in Table 2 and Fig. 2.

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Fig. 1 Flowchart showing the Delphi process.

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Fig. 2 Geographical distribution of panelists. N, number. Copied from Jacobsen ME, Nayahangan LJ, Ghidinelli M, Subramaniam C, Hare KB, Konge L, Gustafsson A. Assessment of Technical Competence in Distal Radius Fracture Fixation by a Volar Locking Plate: A Global Delphi Consensus Study. J Hand Surg Am. 2023 Sep; 48(9):875–885. doi: 10.1016/j.jhsa.2023.05.012. Open access under the CC BY 4.0 license (https://creativecommons.org/licenses/by/4.0/).

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4 Discussion

This study identified 34 assessment parameters for evaluating technical competence in antegrade intramedullary nailing of simple femoral shaft fractures (AO/OTA 32A3. b) through a four-round international Delphi process. The consistently high importance ratings and strong correlation with assigned weights reflect substantial expert consensus and agreement on the procedural factors most critical to surgical quality and safety. These findings offer a structured foundation for competency-based assessment and high-specificity feedback, supporting both clinical instruction and future integration into simulation-based training environments.

Parameters 1 and 25 address fracture reduction before and after nail insertion, respectively. Parameter 1, “Relative reduction with correct length, angulation, and rotation,” underscores the critical role of achieving proper alignment prior to nailing. Inadequate initial reduction is well-documented to increase the risk of chronic malalignment.²¹ Parameter 25 focuses on the residual fracture gap following nail insertion; excessive gap has been associated with an increased risk of malunion and implant failure.²²

Guidewire placement and advancement were captured in six parameters, encompassing both the entry point and the distal positioning of the ball-tipped guidewire. While direct evidence regarding optimal trajectory and placement remains limited, existing studies indicate that a suboptimal entry point may increase the risk of iatrogenic fractures, malrotation, and malunion.^23–25

Parameters 9–12 relate to the reaming phase of the procedure. While the benefits of reaming have been debated, two meta-analyses support its use²⁶ and highlight the importance of over-reaming to reduce the risk of iatrogenic fractures,²⁷ directly aligning with Parameter 9 and 10 respectively.

Five parameters address nail sizing and final placement. Undersized nails have been linked to an increased risk of nonunion.^22,28 In terms of length, a nail that is too short may elevate the risk of periprosthetic fracture,²⁹ while an excessively long nail can protrude proximally or distally. Proximal protrusion has been associated with soft tissue irritation and poorer patient-reported outcomes,³⁰ whereas distal protrusion beyond the epiphyseal scar increases the risk of intercondylar fractures or intra-articular penetration.³¹

Although direct evidence supporting the use of fluoroscopy specifically during nail advancement past the fracture site (Parameter 19) is limited, the literature consistently emphasizes the importance of maintaining fracture reduction during nail insertion.³² This is most effectively monitored using intraoperative fluoroscopy.³³

Parameters 22–30 address the interlocking of the nail both proximally and distally. Regarding parameter 22—the correct sequence of locking—there is no clear consensus in the literature. However, the widespread use of the backstroke technique to control the fracture gap³⁴ suggests a potential advantage in initiating with distal interlocking. While the number and configuration of interlocking screws are known to affect construct stability,³⁵ most existing studies have focused primarily on screw configuration.^35,36

The drilling process and appropriate screw lengths are well studied, with substantial evidence linking over-drilling and screw protrusion to risks of vascular injury and chronic pain.^37,38 Distal interlocking, in particular, is a technically demanding step. Attempts to correct a misaligned trajectory carry the risk of malrotation and drill bit breakage.^39,40 Moreover, repeated attempts not only weaken the surrounding bone but also make successful interlocking increasingly difficult.⁴¹

A single parameter addresses the physical examination of the knee ligaments. This step is clinically relevant, as a substantial proportion of patients with femoral shaft fractures present with concomitant, often unrecognized, ligamentous injuries, which can influence overall outcomes.^42,43

While all included parameters were rated as important by the expert panel, clinical or biomechanical evidence was not available for every item. In many cases, ethical constraints preclude direct comparison between standard techniques and practices considered suboptimal—such as advancing the nail without fluoroscopic guidance or failing to secure the guidewire during reamer withdrawal—thereby limiting opportunities for empirical validation.⁴⁴

A commonly recognized challenge in comprehensive Delphi studies is the difficulty in achieving high recruitment rates.¹⁷ In this study, the recruitment rate was 28 %, reflecting this well-documented limitation. Several factors may have contributed to the modest response: invitations were distributed via an existing email list, which may not have been fully up to date; some addresses may have been inactive; and some messages may have been filtered as spam. Additionally, since inclusion and exclusion criteria were stated in the invitation, some recipients may have self-excluded. Nevertheless, the final number of participants exceeded the average reported in Delphi studies.⁴⁵ The use of online questionnaires facilitated global recruitment, helping to mitigate the influence of national or regional surgical practices. However, panelists from Africa, Oceania, and South America were underrepresented, which may limit the applicability of the findings in those regions.

An additional methodological consideration concerns the structure of the Delphi process. The same panel of experts generated the assessment parameters, rated their importance, and subsequently assigned weights. While this continuity likely contributed to the very strong correlation observed between importance ratings and weight scores (Pearson's r = 0.94), it also introduces a potential bias: parameters perceived as important were likely to be weighted more heavily by the same individuals. As such, the weights should be interpreted with some caution—not as independent indicators of clinical priority, but rather as a structured reflection of the panel's internal consistency. This limitation is also evident in the compressed distribution of weight scores in the final round, with all parameters receiving high values and relatively modest differences between them.

A final limitation relates to the declining response rate across the four Delphi rounds—from 84 % in round 1–45 % in round 4. Given the breadth of the questionnaire, which covered seven distinct procedures, this attrition was anticipated. Prior research has shown that longer surveys are associated with reduced response rates, lower recruitment, and potentially diminished response quality as respondents progress through the questionnaire.⁴⁶ As a result, some panelists who might have contributed valuable insights may have disengaged before completing all rounds. Nonetheless, both the recruitment and response rates achieved in this study are within the acceptable range for the Delphi methodology.¹⁸

Building on the strengths of its international Delphi methodology, this study offers a robust foundation for advancing structured assessment in orthopedic education. Rather than relying on opportunistic clinical exposure, this work supports a more deliberate and evidence-informed approach to teaching and evaluating technical competence in femoral shaft fracture nailing. Specifically, it illustrates how Step 3 of Kern's six-step approach¹¹—the definition of explicit learning objectives—can be met through expert consensus. In parallel, the study provides content validity evidence in line with Messick's contemporary framework,¹⁴ reinforcing the educational and psychometric strengths of the proposed assessment parameters.

The detailed set of parameters developed here reflects broad consensus on the procedural steps most critical to surgical safety and quality. This structured output can underpin objective assessments and support focused, procedure-specific feedback in both clinical and simulation-based training environments. Such specificity is particularly important for guiding learners toward actionable technical improvements,⁴⁷ as generic global rating scales often lack the resolution to do so effectively.⁴⁸

While translation into assessment tools for routine clinical use may require adaptation or prioritization, the current list provides a robust starting point for formative evaluation, summative assessment, and curriculum design. Moreover, the parameters are well suited for integration into simulation-based education platforms, including future virtual reality systems, where they can guide development of structured feedback mechanisms aligned with CBME principles.^14,49

Given that intramedullary nailing of FSF is considered a core competency for general orthopedic surgeons, structured assessment tools grounded in expert consensus represent a meaningful step toward ensuring consistent educational standards. This study contributes novel evidence to support both curriculum development and content validation—helping ensure that FSF fixation is not only taught, but taught in a way that is measurable, meaningful, and reproducible.

5 Conclusion

This study offers a structured, expert-derived foundation for the assessment of technical competence in antegrade intramedullary nailing of femoral shaft fractures. The identified parameters reflect broad international consensus on procedural priorities essential to surgical safety and quality. The findings support the development of assessment tools that enable targeted feedback, objective evaluation, and structured skills training. Whether applied in the operating room or integrated into simulation-based education, these parameters offer a practical pathway towards more consistent and meaningful assessment of surgical performance.

Guardian patient consent

This study did not involve patients, patient data, or identifiable material. All participating expert panelists provided informed consent prior to inclusion.

Ethical statement

Ethical approval was waived by the regional ethics committee of Zealand (EMN-2020-38838).

Author contributions

Mikkel Engell Sandager Nielsen: Formal analysis, Writing – Original Draft. Mads Emil Jacobsen: Conceptualization, Methodology, Software, Formal analysis, Investigation, Writing – Review & Editing, Resources, Project administration. Leizl Joy Nayahangan: Conceptualization, Methodology, Writing – Review & Editing. Monica Ghidinelli: Conceptualization, Resources, Writing – Review & Editing. Chitra Subramaniam: Conceptualization, Resources, Writing – Review & Editing. Kristoffer Borbjerg Hare: Conceptualization, Formal analysis, Writing – Review & Editing. Lars Konge: Conceptualization, Methodology, Supervision, Project administration, Writing – Review & Editing. Amandus Gustafsson: Conceptualitzation, Methodology, Investigation, Resources, Writing – Review & Editing, Supervision, Project administration.

Funding

Mads Emil Jacobsen was supported by research grants from the following not-for-profit funders:

Helsefonden, Denmark (grant no. 22-B-0148) and Gangstedfonden, Denmark (grant no. A43414) and Toyota-Fonden, Denmark (grant no. KJ/BG-10053H).

Funders have not had any influence on any aspect of study design, data collection, data analysis, interpretation of results, or manuscript preparation.

Other funding to declare:

Mikkel Engell Sandager Nielsen received a research grant for an unrelated project from Novo Nordisk Foundation (NNF). The NNF have not had any influence on any aspect of study design, data collection, data analysis, interpretation of results, or manuscript preparation.

Mads Emil Jacobsen received a research grant for unrelated projects from the following non-profit funders: Frimodt-Heineke Fonden, Tømmerhandler Johannes Fogs Fond (grant number 2023–0252), and Dagmar Marshalls Fond. Funders have not had any influence on any aspect of study design, data collection, data analysis, interpretation of results, or manuscript preparation.