Development of a cast application simulator and evaluation of objective measures of performance

Surgical simulation offers a low-risk learning environment with repetitive practice opportunities for orthopaedic residents. It is increasingly prevalent in many training programs, as acquisition of technical skills in the face of educational demands and reduced work hours becomes more challenging. In addition to surgical skills, orthopaedic residents must also learn the technique of cast application. Deficiencies in casting skill are risk factors for re-displacement of fractures and cast-specific complications. Formal educational models to instruct or to evaluate casting technique have not been well described or tested. The purposes of this study were to develop a cast application simulator and to validate a novel method of evaluating casting skill.

A module that simulates short arm cast application on a synthetic forearm model was developed. An Objective Structured Assessment of Technical Skill checklist was created with use of Delphi methodology involving nine content experts (five orthopaedic surgeons and four orthopaedic technologists). Nine participants (three medical students, three orthopaedic residents, two orthopaedic fellows, and one orthopaedic technologist) were used to evaluate the reliability and validity of the checklist. Nine de-identified videos of cast application were recorded and were utilized to test the newly developed Objective Structured Assessment of Technical Skill checklist and Modified Global Rating Scale for reliability and validity. Participants were grouped by training level (medical students, orthopaedic residents, and orthopaedic fellows or orthopaedic technologists) and were evaluated twice.

Reliability was high as shown by intraclass correlation. The inter-rater reliability was 0.85 for the Objective Structured Assessment of Technical Skill, 0.81 for the Modified Global Rating Scale performance, and 0.78 for the Modified Global Rating Scale final product; the intra-rater reliability was 0.88 for the Objective Structured Assessment of Technical Skill, 0.85 for the Modified Global Rating Scale performance, and 0.81 for the Modified Global Rating Scale final product. The Objective Structured Assessment of Technical Skill checklist scores were 9.28 points for the medical students, 17.46 points for the orthopaedic residents, and 18.85 points for the orthopaedic fellows or orthopaedic technologists (p < 0.05, F = 6.32). The Modified Global Rating Scale performance and final product scores also reflected the level of training. Post hoc analysis showed a significant difference between the medical students and orthopaedic fellows or orthopaedic technologists for the Objective Structured Assessment of Technical Skill checklist and Modified Global Rating Scale.

This casting simulation model and evaluation instrument is a reliable assessment of casting skill in applying a short arm cast. However, given the inability to stratify all three groups on the basis of the level of training, further work is needed to establish construct validity.