Fully Threaded Versus Partially Threaded Screws: Determining Shear in Cancellous Bone Fixation

Downey, Michael W.; Kosmopoulos, Victor; Carpenter, Brian

doi:10.1053/j.jfas.2015.04.017

Cited by 29 publications

(28 citation statements)

References 27 publications

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“…Similarly, Thompson et al demonstrated that the pullout strength of a long threaded screw was twice that of a short threaded screw. Downey et al compared partially threaded and fully threaded screw strength in cancellous bone and found that fully threaded screws decrease strain and therefore better resist shear across fracture fragments.…”

Section: Discussionmentioning

confidence: 99%

Achieving interfragmentary compression without special drilling technique or screw design

Eastman

Deafenbaugh

Christiansen

et al. 2017

Journal Orthopaedic Research

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Section: Discussionmentioning

confidence: 99%

Achieving interfragmentary compression without special drilling technique or screw design

Eastman

Deafenbaugh

Christiansen

et al. 2017

Journal Orthopaedic Research

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“…Surgeons should be aware that there is a difference between using a full-thread screw and subchondral fixation versus using a partial thread screw and compression. 14 Our technique with fully threaded screws ensured engagement of both subchondral cortices, not one.…”

Section: Resultsmentioning

confidence: 97%

Biomechanical Comparison of Low-Profile Contoured Locking Plate With Single Compression Screw to Fully Threaded Compression Screws for First MTP Fusion

et al. 2019

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Background: Open metatarsophalangeal (MTP) arthrodesis using locked plates produces good clinical outcomes. However, arthroscopic fusion with new-generation fully threaded compression screws is emerging as an alternative. The purpose of this study was to compare low-profile contoured locked plates with fully threaded compression screws for first MTP fusion, in a biomechanical cadaveric model. Methods: The first rays of 8 matched pairs of fresh frozen cadaveric feet underwent dissection and dual-energy x-ray absorptiometry (DEXA) scanning to measure bone mineral density (BMD). The “plate” group was prepared with cup-and-cone reamers, and fixation of the MTP joint with 1 compression screw and low-profile dorsal locked plate. The matched-pair “screws” group was prepared through a simulated arthroscopic technique, achieving fixation with 2 new-generation fully threaded compression screws. The plantar MTP gap was recorded with an extensometer during 250 000 90-N cyclic loads followed by a single load to failure. Results: The screw group demonstrated significantly greater stiffness, 31.6 N/mm (plates) and 51.7 N/mm (screws) ( P = .0045). There was no significant difference in plantar gapping or load to failure, 198.6 N (plates) and 290.1 N (screws) ( P = .2226). Stiffness and load to failure were highly correlated to BMD for the screw group, r =0.79 and r = 0.94, respectively, but less so for the plate group, r = 0.36 and r = 0.62, respectively. The maximum metatarsal head height measured on the lateral view was strongly correlated with load to failure for both the plate- and screw-only groups ( r > 0.9). Conclusion: These data demonstrate that hallux MTP arthrodesis utilizing fully threaded compression screws had similar plantar gapping and load to failure when compared with the low-profile locking plate, but with significantly more stiffness. These results support an increased role of fully threaded screws for MTP arthrodesis using either the arthroscopic or open technique. However, with decreased BMD plate fixation may remain the better fixation choice. Clinical Relevance: Our data suggest that with regard to construct stability, fully threaded headless compression screws may be just as effective as low-profile locking plates, but BMD and MTP joint fluoroscopic measurements should be considered in the decision-making process for fixation.

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“…Stiffness was calculated as the slope of a best-fit line for the linear region of the force–displacement curve. Yield force was determined using a 0.05 mm offset parallel to the stiffness 27 . Ultimate force for the axial pullout test was the force measured at the peak of the curve, and for the lateral migration test, it was defined as the force at 5 mm of lateral migration.…”

Section: Methodsmentioning

confidence: 99%

Lateral migration resistance of screw is essential in evaluating bone screw stability of plate fixation

Feng

Zhang

et al. 2021

Sci Rep

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Conventional evaluation of the stability of bone screws focuses on pullout strength, while neglecting lateral migration resistance. We measured pullout strength and lateral migration resistance of bone screws and determined how these characteristics relate to screw stability of locking plate (LP) and dynamic compression plate (DCP) fixation. Pullout strength and lateral migration resistance of individual bone screws with buttress, square, and triangular thread designs were evaluated in polyurethane foam blocks. The screw types with superior performance in each of these characteristics were selected. LP and DCP fixations were constructed using the selected screws and tested under cyclic craniocaudal and torsional loadings. Subsequently, the association between individual screws’ biomechanical characteristics and fixation stability when applied to plates was established. Screws with triangular threads had superior pullout strength, while screws with square threads demonstrated the highest lateral migration resistance; they were selected for LP and DCP fixations. LPs with square-threaded screws required a larger force and more cycles to trigger the same amount of displacement under both craniocaudal and torsional loadings. Screws with triangular and square threads showed no difference in DCP fixation stability under craniocaudal loading. However, under torsional loading, DCP fixation with triangular-threaded screws demonstrated superior fixation stability. Lateral migration resistance is the primary contributor to locking screw fixation stability when applied to an LP in resisting both craniocaudal and torsional loading. For compression screws applied to a DCP, lateral migration resistance and pullout strength work together to resist craniocaudal loading, while pullout strength is the primary contributor to the ability to resist torsional loading.

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Fully Threaded Versus Partially Threaded Screws: Determining Shear in Cancellous Bone Fixation

Cited by 29 publications

References 27 publications

Achieving interfragmentary compression without special drilling technique or screw design

Achieving interfragmentary compression without special drilling technique or screw design

Biomechanical Comparison of Low-Profile Contoured Locking Plate With Single Compression Screw to Fully Threaded Compression Screws for First MTP Fusion

Lateral migration resistance of screw is essential in evaluating bone screw stability of plate fixation

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