Wrist movements induce torque and lever force in the scaphoid: an ex vivo study
Abstract Purpose We hypothesised that intercarpal K-wire fixation of adjacent carpal bones would reduce torque and lever force within a fractured scaphoid bone. Methods In eight cadaver wrists, a scaphoid osteotomy was stabilised using a locking nail, which also functioned as a sensor to measure iso...
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doaj-009cd3def8484641b676d36af92dde3e2020-11-25T02:43:32ZengBMCJournal of Orthopaedic Surgery and Research1749-799X2020-08-0115111010.1186/s13018-020-01897-yWrist movements induce torque and lever force in the scaphoid: an ex vivo studyJochen Erhart0Ewald Unger1Philip Schefzig2Peter Varga3Michael Hagmann4Robin Ristl5Stefan Hajdu6Anna Gormasz7Patrick Sadoghi8Winfried Mayr9Department of Trauma Surgery, Medical University of ViennaCenter for Medical Physics and Biomedical Engineering, Medical University of ViennaDepartment of Trauma Surgery, Medical University of ViennaAO FoundationCore Unit of Medical Statistics Medical Statistics and InformaticsCore Unit of Medical Statistics Medical Statistics and InformaticsDepartment of Trauma Surgery, Medical University of ViennaDepartment of Trauma Surgery, Medical University of ViennaDepartment of Orthopedic and Trauma Surgery, Medical University GrazCenter for Medical Physics and Biomedical Engineering, Medical University of ViennaAbstract Purpose We hypothesised that intercarpal K-wire fixation of adjacent carpal bones would reduce torque and lever force within a fractured scaphoid bone. Methods In eight cadaver wrists, a scaphoid osteotomy was stabilised using a locking nail, which also functioned as a sensor to measure isometric torque and lever forces between the fragments. The wrist was moved through 80% of full range of motion (ROM) to generate torque and force within the scaphoid. Testing was performed with and without loading of the wrist and K-wire stabilisation of the adjacent carpal bones. Results Average torque and lever force values were 49.6 ± 25.1 Nmm and 3.5 ± 0.9 N during extension and 41 ± 26.7 Nmm and 8.1 ± 2.8 N during flexion. Torque and lever force did not depend on scaphoid size, individual wrist ROM, or deviations of the sensor versus the anatomic axis. K-wire fixation did not produce significant changes in average torque and lever force values except with wrist radial abduction (P = 0.0485). Other than wrist extension, torque direction was not predictable. Conclusion In unstable scaphoid fractures, we suggest securing rotational stability with selected implants for functional postoperative care. Wrist ROM within 20% extension and radial abduction to 50% flexion limit torque and lever force exacerbation between scaphoid fragments.http://link.springer.com/article/10.1186/s13018-020-01897-yScaphoid fractureBiomechanicsWrist movementTorque and lever force |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Jochen Erhart Ewald Unger Philip Schefzig Peter Varga Michael Hagmann Robin Ristl Stefan Hajdu Anna Gormasz Patrick Sadoghi Winfried Mayr |
spellingShingle |
Jochen Erhart Ewald Unger Philip Schefzig Peter Varga Michael Hagmann Robin Ristl Stefan Hajdu Anna Gormasz Patrick Sadoghi Winfried Mayr Wrist movements induce torque and lever force in the scaphoid: an ex vivo study Journal of Orthopaedic Surgery and Research Scaphoid fracture Biomechanics Wrist movement Torque and lever force |
author_facet |
Jochen Erhart Ewald Unger Philip Schefzig Peter Varga Michael Hagmann Robin Ristl Stefan Hajdu Anna Gormasz Patrick Sadoghi Winfried Mayr |
author_sort |
Jochen Erhart |
title |
Wrist movements induce torque and lever force in the scaphoid: an ex vivo study |
title_short |
Wrist movements induce torque and lever force in the scaphoid: an ex vivo study |
title_full |
Wrist movements induce torque and lever force in the scaphoid: an ex vivo study |
title_fullStr |
Wrist movements induce torque and lever force in the scaphoid: an ex vivo study |
title_full_unstemmed |
Wrist movements induce torque and lever force in the scaphoid: an ex vivo study |
title_sort |
wrist movements induce torque and lever force in the scaphoid: an ex vivo study |
publisher |
BMC |
series |
Journal of Orthopaedic Surgery and Research |
issn |
1749-799X |
publishDate |
2020-08-01 |
description |
Abstract Purpose We hypothesised that intercarpal K-wire fixation of adjacent carpal bones would reduce torque and lever force within a fractured scaphoid bone. Methods In eight cadaver wrists, a scaphoid osteotomy was stabilised using a locking nail, which also functioned as a sensor to measure isometric torque and lever forces between the fragments. The wrist was moved through 80% of full range of motion (ROM) to generate torque and force within the scaphoid. Testing was performed with and without loading of the wrist and K-wire stabilisation of the adjacent carpal bones. Results Average torque and lever force values were 49.6 ± 25.1 Nmm and 3.5 ± 0.9 N during extension and 41 ± 26.7 Nmm and 8.1 ± 2.8 N during flexion. Torque and lever force did not depend on scaphoid size, individual wrist ROM, or deviations of the sensor versus the anatomic axis. K-wire fixation did not produce significant changes in average torque and lever force values except with wrist radial abduction (P = 0.0485). Other than wrist extension, torque direction was not predictable. Conclusion In unstable scaphoid fractures, we suggest securing rotational stability with selected implants for functional postoperative care. Wrist ROM within 20% extension and radial abduction to 50% flexion limit torque and lever force exacerbation between scaphoid fragments. |
topic |
Scaphoid fracture Biomechanics Wrist movement Torque and lever force |
url |
http://link.springer.com/article/10.1186/s13018-020-01897-y |
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