A central threadless shaft screw is better than a fully threaded variable pitch screw for unstable scaphoid nonunion: A biomechanical study

Koh, Il-Hyun; Kang, Ho‐Jung; Kim, Ji-Sup; Park, Seong-Jin; Choi, Youn Jin

doi:10.1016/j.injury.2015.01.018

Cited by 17 publications

(26 citation statements)

References 25 publications

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“…The threadless central shaft screw design (all screws investigated in this study) is biomechanically preferable to the fully threaded variable pitch screw design because it achieves higher or identical compression forces at different interfragmentary gaps with similar stiffness and loads, even though the threadless central shaft screws show a greater loss of compression force over time [20]. The compression force generated by a screw is thought to be an important factor in facilitating union by reducing the fracture gap and improving fracture surface interdigitation, thereby promoting primary bone healing and increasing rotational and bending stability [11,[21][22][23][24][25].…”

Section: Discussionmentioning

confidence: 99%

“…What does the lowest compression force (47 N) found in this experiment mean? Koh et al [20] observed the following forces in a scaphoid bone model: 21 N (Acutrac screw), 28 N (Herbert-Whipple screw), and 45 N (HCS 3.0 screw). Therefore, the interfragmentary compression force observed in this study seems appropriate because forces of 100-200 N were detected for 1.8-and 2.0-mm screws.…”

Section: Discussionmentioning

confidence: 99%

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Comparison of compression screws used for mandible head fracture treatment—experimental study

Kozakiewicz

2019

Clin Oral Invest

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Objectives Compression screws that can fix a fracture of the condylar head of the mandible are available. Although typical titanium lag screws are generally used, a series of headless screws have been designed for this purpose. The Bheadless^advantage derived from the complete submergence of the screw in the bone after fixation is the lack of irritation of the lateral ligament of the temporo-mandibular joint by the screw head. The aim of this study is to compare the compression force of typically used lag screws with that of newly developed headless compression screws. Materials and methods This study tested five types of screws with a 14-mm length: 10 2.0-mm lag screws and 40 headless screws (four groups of equal size: 1.5-mm H screws, 1.8-mm H screws, 2.0-mm H screws, and 1.8-mm W screws). Two cuboid blocks of standardized polyurethane foam were fixed by one screw. The maximal compression force (F in N) and torque at maximal compression force (T in Ncm) were tested according to the guidelines of the American Society for Testing and Materials (ASTM F1839-08). Results The test results were as follows: 2.0-mm lag screw:

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Comparison of compression screws used for mandible head fracture treatment—experimental study

Kozakiewicz

2019

Clin Oral Invest

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“…Our study includes load to failure data that is comparable to those of similar investigations, typically within 100 N of force, with differences likely due to variation in density, direction of applied force, and anatomic variance between models or specimens. 22,23,25,26 Scaphoid nonunion is often accompanied by a collapse deformity or segmental defect in bone. 1,10 The authors believe that an ideal fixation device for scaphoid nonunion would provide both sufficient structural support and accommodate the use of biologically superior cancellous bone graft.…”

Section: Discussionmentioning

confidence: 99%

“…24,25 A 45-degree angle is also within the 30-to 60degree range of documented radioscaphoid angles. 26 Clamps placed at either pole of this model transmit axial compression, which at a 45-degree angle recreates the dorsal to volar cantilever force. This bending force is described as the principal physiologic load that the scaphoid encounters from oblique loading by the trapezium, trapezoid, and capitate.…”

Section: Methodsmentioning

confidence: 99%

A Biomechanical Comparison of Screw and Plate Fixations for Scaphoid Fractures

et al. 2017

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Headless screw fixation is the current gold standard of surgical repair for scaphoid fractures. However, maintaining reduction of certain types of scaphoid fractures is challenging with a compression screw. Plate fixation may offer superior fixation in some scaphoid fractures, particularly those with comminution, nonunion, segmental bony defects, and osteopenic or osteoporotic bone. This study questions whether method of fixation is a determinant in load to failure in segmental scaphoid fractures, and whether any fixation provides a greater mechanical advantage in simulated normal versus osteoporotic bone. Polyurethane models were fashioned to simulate scaphoids with 3-mm segmental defects. Defects were bridged by one of three constructs: a locking plate, a nonlocking plate, or a headless compression screw. Three models for each fixation construct were tested for both simulated normal and osteoporotic bone density. Load to failure was recorded as the load at which the 3-mm segmental defect was closed. Gap closure occurred in all trials. In simulated normal bone, there were no statistically significant differences in load to failure between fixation methods. In simulated osteoporotic bone, the locking plate had a 28% greater load to failure as compared with screw fixation. While biomechanical testing shows that plate and screw fixations are equivalent in normal density bone for fixation of a segmental scaphoid defect, locking plates are superior to screw fixation in simulated osteoporotic bone models. Plate fixation may provide superior fixation for complex scaphoid fractures, particularly in osteopenic bone.

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“…Stiffness is a commonly reported characteristic in orthopedic biomechanical studies, described as the resistance a structure has to deformation. 1,18,19 The adequate amount of stiffness for scaphoid fracture fixation in clinical practice, however, has not been clearly defined. The present study found no significant differences between fixation constructs with regard to overall stiffness.…”

Section: Discussionmentioning

confidence: 99%

Mechanical Evaluation of Four Internal Fixation Constructs for Scaphoid Fractures

Beutel

Melamed

Hinds

et al. 2016

Hand (New York, N,Y.)

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A central threadless shaft screw is better than a fully threaded variable pitch screw for unstable scaphoid nonunion: A biomechanical study

Cited by 17 publications

References 25 publications

Comparison of compression screws used for mandible head fracture treatment—experimental study

Comparison of compression screws used for mandible head fracture treatment—experimental study

A Biomechanical Comparison of Screw and Plate Fixations for Scaphoid Fractures

Mechanical Evaluation of Four Internal Fixation Constructs for Scaphoid Fractures

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