Bone deformities are often complex three-dimensional (3D) deformities, and correcting them is difficult. To correct persistent clubfoot deformity in adolescents or adults, an external fixator is sometimes used to encourage tissue growth and preserve healthy tissues. However, it is difficult to set up, resulting in long surgeries and steep learning curves for surgeons. It is also bulky and obstructs patient mobility. In this paper, we introduce a new approach of defining clubfoot deformity correction as a six degrees-of-freedom (6DOF) correction, and then reducing it to just two degrees-of-freedom (2DOF) using the axis-angle representation. Therefore, only two physical trajectory joints are needed, which in turn enables a more compact fixator design. A computer planner was developed to minimize the bulk of the external fixator, and to optimize the distraction schedule to avoid overstretching the soft tissues. This reduces the learning curve for surgeons and shortens surgery time. To validate the system, a patient-specific clubfoot simulator was developed, and four experiments were performed on the clubfoot simulator. The accuracy of midfoot correction was 11 mm and 3.5 deg without loading, and 41 mm and 11.7 deg with loading. While the external fixator has to be more rigid to overcome resistance against correction, the surgical system itself was able to achieve accurate correction in less than 2 h. This is an improvement from the current method, which takes 2.5–4.5 h.
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June 2019
Research-Article
Compact Two Degrees-of-Freedom External Fixator System for Correction of Persistent Clubfoot Deformity
Ying Ying Wu,
Ying Ying Wu
Department of Biomedical Engineering,
Carnegie Mellon University,
5000 Forbes Avenue,
Pittsburgh, PA 15213
e-mail: yingyinw@alumni.cmu.edu
Carnegie Mellon University,
5000 Forbes Avenue,
Pittsburgh, PA 15213
e-mail: yingyinw@alumni.cmu.edu
1Corresponding author.
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Anton Plakseychuk,
Anton Plakseychuk
Bone and Joint Center,
Magee Womens Hospital,
University of Pittsburgh Medical Center,
300 Halket Street,
Pittsburgh, PA 15213
e-mail: plakap@upmc.edu
Magee Womens Hospital,
University of Pittsburgh Medical Center,
300 Halket Street,
Pittsburgh, PA 15213
e-mail: plakap@upmc.edu
Search for other works by this author on:
Kenji Shimada
Kenji Shimada
Department of Mechanical Engineering,
Carnegie Mellon University,
5000 Forbes Avenue,
Pittsburgh, PA 15213
e-mail: shimada@cmu.edu
Carnegie Mellon University,
5000 Forbes Avenue,
Pittsburgh, PA 15213
e-mail: shimada@cmu.edu
Search for other works by this author on:
Ying Ying Wu
Department of Biomedical Engineering,
Carnegie Mellon University,
5000 Forbes Avenue,
Pittsburgh, PA 15213
e-mail: yingyinw@alumni.cmu.edu
Carnegie Mellon University,
5000 Forbes Avenue,
Pittsburgh, PA 15213
e-mail: yingyinw@alumni.cmu.edu
Anton Plakseychuk
Bone and Joint Center,
Magee Womens Hospital,
University of Pittsburgh Medical Center,
300 Halket Street,
Pittsburgh, PA 15213
e-mail: plakap@upmc.edu
Magee Womens Hospital,
University of Pittsburgh Medical Center,
300 Halket Street,
Pittsburgh, PA 15213
e-mail: plakap@upmc.edu
Kenji Shimada
Department of Mechanical Engineering,
Carnegie Mellon University,
5000 Forbes Avenue,
Pittsburgh, PA 15213
e-mail: shimada@cmu.edu
Carnegie Mellon University,
5000 Forbes Avenue,
Pittsburgh, PA 15213
e-mail: shimada@cmu.edu
1Corresponding author.
Manuscript received August 20, 2018; final manuscript received February 16, 2019; published online April 4, 2019. Assoc. Editor: Rita M. Patterson.
J. Med. Devices. Jun 2019, 13(2): 021005 (6 pages)
Published Online: April 4, 2019
Article history
Received:
August 20, 2018
Revised:
February 16, 2019
Citation
Wu, Y. Y., Plakseychuk, A., and Shimada, K. (April 4, 2019). "Compact Two Degrees-of-Freedom External Fixator System for Correction of Persistent Clubfoot Deformity." ASME. J. Med. Devices. June 2019; 13(2): 021005. https://doi.org/10.1115/1.4043109
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