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Biomedical subjects

J P Loan

Publications and source records attributed to J P Loan.

3 recordsLinked to original sources

A virtual reality module for intravenous catheter placement.

BACKGROUND: Virtual reality (VR) is a potential tool for technical skills training. We tested the validity and instructional effectiveness of a prototype VR module for learning intravenous (i.v.) catheter placement. METHODS: First-year medical students (n = 37), third-year medical students (n = 14), and surgical residents (n = 9) attempted two pretest i.v.s into each other, used the VR module for 12 minutes, and subsequently attempted two posttest i.v.s. Success or failure were recorded for each attempt. For each successful attempt, time and global rating of i.v. insertion were also recorded. RESULTS: The pretest success rate was significantly different between groups (chi square = 28.71, P <0.01). VR success rate was not significantly different between groups (F(2,57) = 1.47, ns). Although there was improvement in all groups during VR training (F(2,114) = 44.16, P <0.01), this did not result in improvement in posttest performance. CONCLUSIONS: Significant differences between groups were observed in performance of i.v. insertion in physical reality. However, no significant difference was observed in performance in VR. Thus, performance in VR demonstrated neither construct nor concurrent validity. While performance improved in VR, transfer of skill from VR to physical reality was not observed. Additional development and testing of VR as a training tool is warranted before its widespread use can be recommended.

Catheterization↗

A graphics-based software system to develop and analyze models of musculoskeletal structures.

We have created a graphics-based software system that enables users to develop and analyze musculoskeletal models without programming. To define a model using this system one specifies the surfaces of the bones, the kinematics of the joints and the lines of action and force-generating parameters of the muscles. Once a model is defined, the function of each muscle can be analyzed by computing its length, moment arms, force and joint moments. The software has been implemented on a computer graphics workstation so that users can view the model from any perspective and graphically manipulate the joint kinematics and musculoskeletal geometry. Models can also be animated to visualize the results of motion analysis experiments. Since the software can be used to study models of many different musculoskeletal structures, it can enhance the productivity of investigators working on diverse problems in biomechanics.

Algorithms↗

An interactive graphics-based model of the lower extremity to study orthopaedic surgical procedures.

We have developed a model of the human lower extremity to study how surgical changes in musculoskeletal geometry and musculotendon parameters affect muscle force and its moment about the joints. The lines of action of 43 musculotendon actuators were defined based on their anatomical relationships to three-dimensional bone surface representations. A model for each actuator was formulated to compute its isometric force-length relation. The kinematics of the lower extremity were defined by modeling the hip, knee, ankle, subtalar, and metatarsophalangeal joints. Thus, the force and joint moment that each musculotendon actuator develops can be computed for any body position. The joint moments calculated with the model compare well with experimentally measured isometric joint moments. We developed a graphical interface to the model that allows the user to visualize the musculoskeletal geometry and to manipulate the model parameters to study the biomechanical consequences of orthopaedic surgical procedures. For example, tendon transfer and lengthening procedures can be simulated by adjusting the model parameters according to various surgical techniques. Results of the simulated surgeries can be analyzed quickly in terms of postsurgery muscle forces and other biomechanical variables. Just as interactive graphics have enhanced engineering design and analysis, we have found that graphics-based musculoskeletal models are effective tools for designing and analyzing surgical procedures.

Biomechanical Phenomena↗