Comparison of Screw Trajectory on Stability of Oblique Scaphoid Fractures: A Mechanical Study

Faucher, Gregory K.; Golden, M. Leslie; Sweeney, Kyle R.; Hutton, William; Jarrett, Claudius D.

doi:10.1016/j.jhsa.2013.12.015

Cited by 30 publications

(41 citation statements)

References 18 publications

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“…5 Faucher et al in 2014 also performed a cadaveric analysis of fixation strength in oblique scaphoid fractures and found equivalent strength in cyclic loading and load to failure between PTP and PERP screws. 6 We agree, however, with rationale that computer-based models allow for a more precise comparison. 5 Advantages of a computer model include the ability to control for variability in screw placement and to precisely analyze screw angles.…”

Section: Discussionsupporting

confidence: 61%

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Effect of Screw Perpendicularity on Compression in Scaphoid Waist Fractures

et al. 2016

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Central and perpendicular (PERP) screw orientations have each been described for scaphoid fracture fixation. It is unclear, however, which orientation produces greater compression. This study compares compression in scaphoid waist fractures with screw fixation in both PERP and pole-to-pole (PTP) configurations. PERP orientation was hypothesized to produce greater compression than PTP orientation. Ten preoperative computed tomography scans of scaphoid waist fractures were classified by fracture type and orientation in the coronal and sagittal planes. Three-dimensional models of each scaphoid and fracture plane were created. Simulated Acutrak 2 (Acumed, Hillsboro, OR) screws were placed into the models in both PERP and PTP orientations. Engagement length and screw angle relative to the fracture were measured. Compression strength was calculated from the shear area, average density, and angle acuity. The PTP angle between screw and fracture ranged from 36 to 84 degrees. By definition, the PERP screw-to-fracture angle was 90 degrees. Perpendicularity of the PTP screw to the fracture was positively correlated to compression strength. PERP screws had greater compression than PTP screws when the PTP screw-to-fracture angle was< 80 degrees (106 vs. 80 N), but there was no difference in compression when the PTP screw-to-fracture angle was > 80 degrees, approximating the PERP screw. Increasing screw perpendicularity resulted in higher compression when the screw-to-fracture angle of the PTP screw was< 80 degrees. Maximum compression was obtained with a screw PERP to the fracture. The increased compression gained from PERP screw placement offsets the decreased engagement length. These results provide guidelines for optimal screw placement in scaphoid waist fractures.

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Section: Discussionsupporting

confidence: 61%

“…Others have studied "peripheral," screw placement. 1,3,6,30 Trumble et al in 1996 performed a retrospective clinical evaluation of scaphoid union. 3 They found that cannulated screws placed in the central one-third of the scaphoid were associated with improved time to union as compared with eccentric screws.…”

Section: Discussionmentioning

confidence: 99%

Effect of Screw Perpendicularity on Compression in Scaphoid Waist Fractures

et al. 2016

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“…Previous studies have utilized the matched-pairs technique for testing. 12,15 Future studies could look at the effect of bone density on stiffness and ultimate load in the fixation of scaphoid fractures.…”

Section: Discussionmentioning

confidence: 99%

“…14 Additional mechanical studies have attempted to determine whether an eccentrically or centrally fixed screw across scaphoid waist fractures would withstand less displacement during cyclic loading and greater ultimate load during load to failure testing. 12,15,16 A current recommendation for stabilizing scaphoid waist fractures involves placing a headless compression screw of maximum length along the long axis of the scaphoid. 17 A previous study found that scaphoid fracture fixation with longer length headless compression screws decreased fracture fragment motion possibly due to the increase in purchase, or bone-screw interaction between the scaphoid and screw.…”

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confidence: 99%

Impact of Screw Length on Proximal Scaphoid Fracture Biomechanics

et al. 2019

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Background Proximal scaphoid fractures display high nonunion rates and increased revision cases. Waist fracture fixation involves maximizing screw length within the cortex; however, the optimal screw length for proximal scaphoid fractures remains unknown. Purpose The main purpose of this article is to compare stiffness and ultimate load for proximal scaphoid fracture fixation of various headless compression screw lengths. Methods Eighteen scaphoids underwent an osteotomy simulating a 7 mm oblique proximal fracture. Screws of three lengths (10, 18, and 24 mm) were randomly assigned for fixation. Each specimen underwent cyclic loading with stiffness calculated during the last loading cycle. Specimens that withstood cyclic loading were loaded to failure. Results No significant difference in stiffness between screw lengths was found. Ultimate load was significantly impacted by the screw length. A significant difference in ultimate load between a 10 and 24 mm screw was found; however, no significant difference occurred in ultimate load between an 18 and 24 mm screw. Conclusions No significant difference in stiffness between all groups could be due to similarities in purchase in the proximal aspect. The 10 mm screw withstanding less ultimate load compared to the 24 mm screw could be due to the 10 mm screw gaining less purchase on either side of the fracture site compared to the 24 mm screw. Lack of significant difference in ultimate load between the 18 and 24 mm screw could be occurring because the fracture site is closer to the 18 mm screw midpoint, as distal threads are engaged closer to the fracture. Clinical Relevance Maximizing screw length may not provide superior fixation biomechanically compared with fixation utilizing a 6 mm shorter screw for proximal scaphoid fractures.

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“…In a biomechanical study, Faucher et al noted that in an oblique scaphoid fracture, a screw placed perpendicular to the fracture plane could be shorter in length but preserve the strength of fixation when compared to a screw placed centrally (20). …”

Section: Discussionmentioning

confidence: 99%

Radiographic Parameters to Predict Union After Volar Percutaneous Fixation of Herbert Type B1 and B2 Scaphoid Fractures

Mahmoud

Hegazy

Khaled

et al. 2016

The Journal of Hand Surgery

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Purpose To study the angle of screw placement in relation to the scaphoid fracture plane and its effect on union after percutaneous fixation of scaphoid waist fractures. Methods Twenty-four consecutive scaphoid waist fractures were retrospectively evaluated for the orientation of screws in relation to the fracture plane using a method in which the sum-of-smaller angles (SSA) in three different radiographs were used to correlate with time to fracture union. Results All but one patient achieved union after percutaneous fixation of the scaphoid. One other patient required revision surgery within the study period for inadequate fixation. A shortened time to union was significantly correlated to larger sums of small angles (SSA). Conclusion SSA may be a reasonable predictor of union after percutaneous fixation of scaphoid waist fracture. It can be reliably calculated using plain radiographs. An SSA of 190 degrees or more correlated with union by eight weeks post operatively. Level of evidence Prognostic Retrospective level IV

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Comparison of Screw Trajectory on Stability of Oblique Scaphoid Fractures: A Mechanical Study

Cited by 30 publications

References 18 publications

Effect of Screw Perpendicularity on Compression in Scaphoid Waist Fractures

Effect of Screw Perpendicularity on Compression in Scaphoid Waist Fractures

Impact of Screw Length on Proximal Scaphoid Fracture Biomechanics

Radiographic Parameters to Predict Union After Volar Percutaneous Fixation of Herbert Type B1 and B2 Scaphoid Fractures

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