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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

Comparison of the plantar pressure between computational prediction and experimental measurement in: A) balanced standing position, B) the first peak instant and C) the second peak instant for validation
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pone.0134340.g004: Comparison of the plantar pressure between computational prediction and experimental measurement in: A) balanced standing position, B) the first peak instant and C) the second peak instant for validation

Mentions: Fig 4 shows comparisons of the plantar pressure distributions during the balanced standing and the first and second peak instants between the finite element prediction and the in vivo experimental measurements. To calculate the averaged pressure in concerned regions, rectangles or squares in equivalent areas were created in the model and F-Scan pressure map. The plantar pressure at each node in the involved elements was exported in the visualization module using the report menu and then these values were averaged in excel files. The same procedure was applied to the calculation of average joint contact pressure. The average pressure in selected areas of the F-Scan and K-Scan pressure maps could be directly obtained. In the balanced standing position, the peak pressure from both prediction and measurement was located beneath the heel. The average pressure over a small square area of 1.5 cm2 was 0.168 MPa and 0.157 MPa, respectively. The pressure beneath the heads of the second and third metatarsals was higher than in other regions over the fore-foot. The average pressure over a square area of 2.3 cm2 was 0.051 MPa and 0.058 MPa, respectively. At the first peak instant, the peak pressure was both located at the heel region and the average pressure over the 1.5 cm2 area was 0.300 MPa and 0.307 MPa respectively. The peak pressure at the second instants lied in the fore-foot region. The area of the first, second and third metatarsal heads sustained much higher pressure than other regions and thus the average pressure in a 10 cm2 area covering the first to third metatarsal heads was calculated. It was 0.227 and 0.223 MPa respectively in the finite element prediction and the F-scan measurement.


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

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

Comparison of the plantar pressure between computational prediction and experimental measurement in: A) balanced standing position, B) the first peak instant and C) the second peak instant for validation
© Copyright Policy
Related In: Results  -  Collection

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

pone.0134340.g004: Comparison of the plantar pressure between computational prediction and experimental measurement in: A) balanced standing position, B) the first peak instant and C) the second peak instant for validation
Mentions: Fig 4 shows comparisons of the plantar pressure distributions during the balanced standing and the first and second peak instants between the finite element prediction and the in vivo experimental measurements. To calculate the averaged pressure in concerned regions, rectangles or squares in equivalent areas were created in the model and F-Scan pressure map. The plantar pressure at each node in the involved elements was exported in the visualization module using the report menu and then these values were averaged in excel files. The same procedure was applied to the calculation of average joint contact pressure. The average pressure in selected areas of the F-Scan and K-Scan pressure maps could be directly obtained. In the balanced standing position, the peak pressure from both prediction and measurement was located beneath the heel. The average pressure over a small square area of 1.5 cm2 was 0.168 MPa and 0.157 MPa, respectively. The pressure beneath the heads of the second and third metatarsals was higher than in other regions over the fore-foot. The average pressure over a square area of 2.3 cm2 was 0.051 MPa and 0.058 MPa, respectively. At the first peak instant, the peak pressure was both located at the heel region and the average pressure over the 1.5 cm2 area was 0.300 MPa and 0.307 MPa respectively. The peak pressure at the second instants lied in the fore-foot region. The area of the first, second and third metatarsal heads sustained much higher pressure than other regions and thus the average pressure in a 10 cm2 area covering the first to third metatarsal heads was calculated. It was 0.227 and 0.223 MPa respectively in the finite element prediction and the F-scan measurement.

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