Biomechanical Testing of Distal Radius Fracture Treatments: Boundary Conditions Significantly Affect the Outcome of In Vitro Experiments

2016 ◽  
Vol 32 (2) ◽  
pp. 210-214 ◽  
Author(s):  
Alexander Synek ◽  
Yan Chevalier ◽  
Christian Schröder ◽  
Dieter H. Pahr ◽  
Sebastian F. Baumbach
Keyword(s):  
Boundary Conditions ◽  
Distal Radius Fracture ◽  
Distal Radius ◽  
Plate Osteosynthesis ◽  
Biomechanical Testing ◽  
Biomechanical Properties ◽  
Biomechanical Study ◽  
Radius Fracture ◽  
Compression Tests

The variety of experimental setups used during in vitro testing of distal radius fracture treatments impairs interstudy comparison and might lead to contradictory results. Setups particularly differ with respect to their boundary conditions, but the influence on the experimental outcome is unknown. The aim of this biomechanical study was to investigate the effects of 2 common boundary conditions on the biomechanical properties of an extra-articular distal radius fracture treated using volar plate osteosynthesis. Uniaxial compression tests were performed on 10 synthetic radii that were randomized into a proximally constrained group (ProxConst) or proximally movable group (ProxMove). The load was applied distally through a ball joint to enable distal fragment rotation. A significantly larger (ProxConst vs ProxMove) stiffness (671.6 ± 118.9 N·mm−1 vs 259.6 ± 49.4 N·mm−1), elastic limit (186.2 ± 24.4 N vs 75.4 ± 20.2 N), and failure load (504.9 ± 142.5 N vs 200.7 ± 49.0 N) were found for the ProxConst group. The residual tilt did not differ significantly between the 2 groups. We concluded that the boundary conditions have a profound impact on the experimental outcome and should be considered more carefully in both study design and interstudy comparison.

Simulating Distal Radius Fracture Strength Using Biomechanical Tests: A Modeling Study Examining the Influence of Boundary Conditions

2011 ◽  
Vol 133 (11) ◽  
Author(s):  
W. Brent Edwards ◽  
Karen L. Troy
Keyword(s):  
Boundary Conditions ◽  
Distal Radius Fracture ◽  
Distal Radius ◽  
Fracture Strength ◽  
Wrist Joint ◽  
Biomechanical Testing ◽  
Load Carriage ◽  
Radius Fracture ◽  
Cortical Shell

Distal radius fracture strength has been quantified using in vitro biomechanical testing. These tests are frequently performed using one of two methods: (1) load is applied directly to the embedded isolated radius or (2) load is applied through the hand with the wrist joint intact. Fracture loads established using the isolated radius method are consistently 1.5 to 3 times greater than those for the intact wrist method. To address this discrepancy, a validated finite element modeling procedure was used to predict distal radius fracture strength for 22 female forearms under boundary conditions simulating the isolated radius and intact wrist method. Predicted fracture strength was highly correlated between methods (r = 0.94; p < 0.001); however, intact wrist simulations were characterized by significantly reduced cortical shell load carriage and increased stress and strain concentrations. These changes resulted in fracture strength values less than half those predicted for the isolated radius simulations (2274 ± 824 N for isolated radius, 1124 ± 375 N for intact wrist; p < 0.001). The isolated radius method underestimated the mechanical importance of the trabecular compartment compared to the more physiologically relevant intact wrist scenario. These differences should be borne in mind when interpreting the physiologic importance of mechanical testing and simulation results.

In-Vitro Evaluation of Thumb Spica and Short Arm Cast Immobilization of the Distal Radius Fracture

1993 ◽  
Vol 7 (2) ◽  
pp. 150
Author(s):  
F. S. Lee ◽  
M. B. Dekutoski ◽  
K. Cervone ◽  
S. P. DeSilva ◽  
K. H. Yang
Keyword(s):  
Distal Radius Fracture ◽  
Distal Radius ◽  
Radius Fracture ◽  
Cast Immobilization ◽  
In Vitro Evaluation

Use of Computed Tomography in Determining the Occurrence of Dorsal and Intra-articular Screw Penetration in Volar Locking Plate Osteosynthesis of Distal Radius Fracture

2018 ◽  
Vol 23 (01) ◽  
pp. 26-32 ◽  
Author(s):  
Teik Wei Diong ◽  
Nor Hazla Mohamed Haflah ◽  
Abdul Yazid Mohd Kassim ◽  
Sharifah Majedah Idrus Al Habshi ◽  
Mohd Hassan Shukur
Keyword(s):  
Ct Scan ◽  
Distal Radius Fracture ◽  
Distal Radius ◽  
Locking Plate ◽  
Plate Osteosynthesis ◽  
Plain Radiograph ◽  
Radius Fracture ◽  
Volar Locking Plate ◽  
Screw Length ◽  
Screw Penetration

Background: The use of volar locking plate in distal radius fracture can lead to extensor tendon rupture due to dorsal screw penetration. The aim of our study was to investigate the occurrence of dorsal and intra-articular screw penetration using CT scan after volar distal radius osteosynthesis for distal radius fractures.Methods: Thirty patients who underwent distal volar locking plate for distal radius fracture were included in a retrospective study. In all 30 patients no dorsal and intra-articular screw penetration were detected on standard AP and lateral views of a plain radiograph. CT scan of the operated wrist was performed to determine the number of intra-articular and dorsal screw penetrations. Clinical examination was performed to determine the wrist functions in comparison to the normal wrist.Results: Nineteen wrists were noted to have screw penetration either dorsally or intraarticularly. The highest incidence is in the 2nd extensor compartment where 13 screws had penetrated with a mean of 2.46 mm. Six screws penetrated into the distal radial ulnar joint and five screws into the wrist joint with a mean of 2.83 mm and 2.6 mm, respectively. However, there was no incidence of tendon irritation or rupture.Conclusions: This study demonstrated a high incidence of dorsal and intra-articular screw penetration detected by CT scan which was not apparent in plain radiograph. We recommend that surgeons adhere to the principle of only near cortex fixation and downsizing the locking screw length by 2 mm.

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