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Effects of Ankle Arthrodesis on Biomechanical Performance of the Entire Foot.

Wang Y, Li Z, Wong DW, Zhang M - PLoS ONE (2015)

Bottom Line: An average contact pressure of 2.14 MPa was predicted at the talonavicular joint after surgery and the maximum variation was shown to be 80% in joints of the first ray.The contact force and pressure of the subtalar joint decreased after surgery, indicating that arthritis at this joint was not necessarily a consequence of ankle arthrodesis but rather a progression of pre-existing degenerative changes.Von Mises stress in the second and third metatarsal bones at the second-peak instant increased to 52 MPa and 34 MPa, respectively, after surgery.

View Article: PubMed Central - PubMed

Affiliation: Interdisciplinary Division of Biomedical Engineering, Faculty of Engineering, The Hong Kong Polytechnic University Hong Kong, China; The Hong Kong Polytechnic University Shenzhen Research Institute, Shenzhen, China.

ABSTRACT

Background/methodology: Ankle arthrodesis is one popular surgical treatment for ankle arthritis, chronic instability, and degenerative deformity. However, complications such as foot pain, joint arthritis, and bone fracture may cause patients to suffer other problems. Understanding the internal biomechanics of the foot is critical for assessing the effectiveness of ankle arthrodesis and provides a baseline for the surgical plan. This study aimed to understand the biomechanical effects of ankle arthrodesis on the entire foot and ankle using finite element analyses. A three-dimensional finite element model of the foot and ankle, involving 28 bones, 103 ligaments, the plantar fascia, major muscle groups, and encapsulated soft tissue, was developed and validated. The biomechanical performances of a normal foot and a foot with ankle arthrodesis were compared at three gait instants, first-peak, mid-stance, and second-peak.

Principal findings/conclusions: Changes in plantar pressure distribution, joint contact pressure and forces, von Mises stress on bone and foot deformation were predicted. Compared with those in the normal foot, the peak plantar pressure was increased and the center of pressure moved anteriorly in the foot with ankle arthrodesis. The talonavicular joint and joints of the first to third rays in the hind- and mid-foot bore the majority of the loading and sustained substantially increased loading after ankle arthrodesis. An average contact pressure of 2.14 MPa was predicted at the talonavicular joint after surgery and the maximum variation was shown to be 80% in joints of the first ray. The contact force and pressure of the subtalar joint decreased after surgery, indicating that arthritis at this joint was not necessarily a consequence of ankle arthrodesis but rather a progression of pre-existing degenerative changes. Von Mises stress in the second and third metatarsal bones at the second-peak instant increased to 52 MPa and 34 MPa, respectively, after surgery. These variations can provide indications for outcome assessment of ankle arthrodesis surgery.

No MeSH data available.


Related in: MedlinePlus

Ground reaction forces and ground-shank angle recorded in the gait analysis and the three instants, first-peak, mid-stance, and second-peak, for simulation.The three instants were marked in the curves.
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pone.0134340.g002: Ground reaction forces and ground-shank angle recorded in the gait analysis and the three instants, first-peak, mid-stance, and second-peak, for simulation.The three instants were marked in the curves.

Mentions: Boundary conditions and ground reaction forces were derived from gait analysis, which was carried out using the Vicon Motion Analysis System (Vicon, Oxford Metrics, Oxford, UK) from the same subject as the foot model. Sixteen retro-reflective markers were attached to the subject’s lower limbs to define seven segments, the pelvis, two thighs, two lower legs, and two feet. Static calibration was conducted when the subject stood on an AMTI force platform (Advanced Mechanical Technology, Inc., Watertown, MA, USA). The position of the right foot shank was recorded by creating an angle between the tibia bone and the global system, depicted as angle α in Fig 1. The angle in the sagittal plane was calculated. The curve is shown in Fig 2. Ground reaction forces in the vertical, anteroposterior, and mediolateral directions and the center of pressure were recorded using force platforms. Three typical gait instants as shown in Fig 2, the first-peak, mid-stance, and second-peak in terms of the vertical ground reaction force, were picked for simulation.


Effects of Ankle Arthrodesis on Biomechanical Performance of the Entire Foot.

Wang Y, Li Z, Wong DW, Zhang M - PLoS ONE (2015)

Ground reaction forces and ground-shank angle recorded in the gait analysis and the three instants, first-peak, mid-stance, and second-peak, for simulation.The three instants were marked in the curves.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4519327&req=5

pone.0134340.g002: Ground reaction forces and ground-shank angle recorded in the gait analysis and the three instants, first-peak, mid-stance, and second-peak, for simulation.The three instants were marked in the curves.
Mentions: Boundary conditions and ground reaction forces were derived from gait analysis, which was carried out using the Vicon Motion Analysis System (Vicon, Oxford Metrics, Oxford, UK) from the same subject as the foot model. Sixteen retro-reflective markers were attached to the subject’s lower limbs to define seven segments, the pelvis, two thighs, two lower legs, and two feet. Static calibration was conducted when the subject stood on an AMTI force platform (Advanced Mechanical Technology, Inc., Watertown, MA, USA). The position of the right foot shank was recorded by creating an angle between the tibia bone and the global system, depicted as angle α in Fig 1. The angle in the sagittal plane was calculated. The curve is shown in Fig 2. Ground reaction forces in the vertical, anteroposterior, and mediolateral directions and the center of pressure were recorded using force platforms. Three typical gait instants as shown in Fig 2, the first-peak, mid-stance, and second-peak in terms of the vertical ground reaction force, were picked for simulation.

Bottom Line: An average contact pressure of 2.14 MPa was predicted at the talonavicular joint after surgery and the maximum variation was shown to be 80% in joints of the first ray.The contact force and pressure of the subtalar joint decreased after surgery, indicating that arthritis at this joint was not necessarily a consequence of ankle arthrodesis but rather a progression of pre-existing degenerative changes.Von Mises stress in the second and third metatarsal bones at the second-peak instant increased to 52 MPa and 34 MPa, respectively, after surgery.

View Article: PubMed Central - PubMed

Affiliation: Interdisciplinary Division of Biomedical Engineering, Faculty of Engineering, The Hong Kong Polytechnic University Hong Kong, China; The Hong Kong Polytechnic University Shenzhen Research Institute, Shenzhen, China.

ABSTRACT

Background/methodology: Ankle arthrodesis is one popular surgical treatment for ankle arthritis, chronic instability, and degenerative deformity. However, complications such as foot pain, joint arthritis, and bone fracture may cause patients to suffer other problems. Understanding the internal biomechanics of the foot is critical for assessing the effectiveness of ankle arthrodesis and provides a baseline for the surgical plan. This study aimed to understand the biomechanical effects of ankle arthrodesis on the entire foot and ankle using finite element analyses. A three-dimensional finite element model of the foot and ankle, involving 28 bones, 103 ligaments, the plantar fascia, major muscle groups, and encapsulated soft tissue, was developed and validated. The biomechanical performances of a normal foot and a foot with ankle arthrodesis were compared at three gait instants, first-peak, mid-stance, and second-peak.

Principal findings/conclusions: Changes in plantar pressure distribution, joint contact pressure and forces, von Mises stress on bone and foot deformation were predicted. Compared with those in the normal foot, the peak plantar pressure was increased and the center of pressure moved anteriorly in the foot with ankle arthrodesis. The talonavicular joint and joints of the first to third rays in the hind- and mid-foot bore the majority of the loading and sustained substantially increased loading after ankle arthrodesis. An average contact pressure of 2.14 MPa was predicted at the talonavicular joint after surgery and the maximum variation was shown to be 80% in joints of the first ray. The contact force and pressure of the subtalar joint decreased after surgery, indicating that arthritis at this joint was not necessarily a consequence of ankle arthrodesis but rather a progression of pre-existing degenerative changes. Von Mises stress in the second and third metatarsal bones at the second-peak instant increased to 52 MPa and 34 MPa, respectively, after surgery. These variations can provide indications for outcome assessment of ankle arthrodesis surgery.

No MeSH data available.


Related in: MedlinePlus