scholarly journals Impact of Screw Length on Proximal Scaphoid Fracture Biomechanics

2019 ◽  
Vol 08 (05) ◽  
pp. 360-365 ◽  
Author(s):  
Samik Patel ◽  
Juan Giugale ◽  
Nathan Tiedeken ◽  
Richard E. Debski ◽  
John R. Fowler
Keyword(s):  
Cyclic Loading ◽  
Fracture Fixation ◽  
Ultimate Load ◽  
Scaphoid Fracture ◽  
Fracture Site ◽  
Compression Screw ◽  
Headless Compression Screw ◽  
Scaphoid Fractures ◽  
Screw Length ◽  
Significant Difference

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.

Early results of a new implant: 3.0 mm headless compression screw for scaphoid fracture fixation

2012 ◽  
Vol 37 (7) ◽  
pp. 690-693 ◽  
Author(s):  
K. Singisetti ◽  
E. Aldlyami ◽  
A. Middleton
Keyword(s):  
Internal Fixation ◽  
Fracture Fixation ◽  
Scaphoid Fracture ◽  
Compression Screw ◽  
Headless Compression Screw ◽  
Scaphoid Fractures ◽  
Early Results ◽  
Fracture Nonunions ◽  
Radiological Healing ◽  
Vascularized Bone

There has been a considerable evolution of screws used for internal fixation of scaphoid fractures. We discuss here, early results of a recently introduced implant Synthes 3.0 mm headless compression screw used for scaphoid fracture fixation. Twenty eight patients with scaphoid fractures (five acute and 23 nonunions) were treated with internal fixation by this non-variable pitch screw over a period of 18 months. All nonunions had pedicle vascularized bone grafting. All five patients with acute scaphoid fracture fixation had radiological healing at a mean of 8 weeks. Fifteen of 23 scaphoid fracture nonunions showed definite signs and a further seven showed probable signs of radiological healing at a mean of 8 months. One nonunion has failed to unite after surgery.

scholarly journals Effect of Screw Length and Geometry on Interfragmentary Compression in a Simulated Proximal Pole Scaphoid Fracture Model

Hand ◽  
2018 ◽  
Vol 15 (3) ◽  
pp. 378-383
Author(s):  
Samik Patel ◽  
Juan M. Giugale ◽  
Richard E. Debski ◽  
John R. Fowler
Keyword(s):  
Analysis Of Variance ◽  
Scaphoid Fracture ◽  
Fracture Site ◽  
Proximal Pole ◽  
Scaphoid Fractures ◽  
Screw Length ◽  
Significant Difference ◽  
Headless Compression Screws ◽  
With Screws ◽  
Interfragmentary Compression

Background: The objective of this study was to determine interfragmentary compression forces based on screw length and geometry for simulated proximal scaphoid fractures. Methods: Sixty-four foam model simulated fractures were stabilized with screws of various length (10 mm, 18 mm, 20 mm, or 24 mm) and geometry (central threadless or fully threaded) across a proximal fracture. Interfragmentary compression was measured at the simulated fracture site upon fixation. An independent sample t test and 1-way analysis of variance were performed to assess differences in interfragmentary compression. Results: Fixation utilizing a 10-mm screw generated significantly less interfragmentary compression than fixation utilizing a 20-mm or 24-mm screw. When accounting for both screw length and geometry, an 18-mm central threadless screw generated greater interfragmentary compression than a 20-mm and 24-mm fully threaded screw; there was no significant difference in compression between an 18-mm and 24-mm central threadless screw. Conclusions: The design of headless compression screws allows for maximal interfragmentary compression at the screw midpoint; we questioned whether a short screw centered on the fracture site resulted in superior compression to a longer, noncentered screw. Our data suggest that centering a small screw (10 mm) along a proximal fracture generates significantly less interfragmentary compression than a longer, noncentered screw. Our results demonstrate that balance between maximizing screw length and centering the screw on the fracture is vital toward maximizing interfragmentary compression for the fixation of proximal third scaphoid fractures.

Excessive Derotational K-Wire Angulation Decreases Compression by Headless Compression Screw

2021 ◽  
Author(s):  
Joseph A. Gil ◽  
Michael D. Montague ◽  
Christopher J. Lama ◽  
Peter Brodeur ◽  
Julia A. Katarincic ◽  
...  
Keyword(s):  
Kirschner Wire ◽  
Fracture Site ◽  
Carpal Bone ◽  
Control Group ◽  
Mineral Density ◽  
Compression Screw ◽  
Headless Compression Screw ◽  
Scaphoid Fractures ◽  
Significant Difference ◽  
The Mean

Abstract Background Scaphoid fracture is the most common carpal bone fracture. Open reduction internal fixation of scaphoid fractures typically undergo stabilization by a single headless compression screw (HCS). During screw insertion, a derotational Kirschner wire (K-wire) is often placed for rotational control of the near and far fragment. Questions/purposes The aim of this study was to determine if there is an angle of derotational K-wire placement in relation to the axis of a HCS that compromises the amount of compression generated at a fracture site by the HCS. We hypothesize that increased off-axis angle will lead to decreased compression across the fracture site. Methods A Cellular Block 20 rigid polyurethane foam (Sawbones, Vashon, WA) scaphoid model was created to eliminate variability in bone mineral density in cadaveric bone. MiniAcutrak HCS screws (Acumed, Hillsboro, OR) were used for testing. Three conditions were tested: (1) HCS with derotational wire inserted parallel to the HCS (zero degrees off-axis); (2) HCS with derotational wire inserted 10 degrees off-axis; and (3) HCS with derotational wire inserted 20 degrees off-axis. Results A statistically significant difference in the mean compression of the control group (56.9 N) was found between the mean compression with the derotational K-wire placed 20 degrees off-axis (15.2 N) (p = 0.001). Conclusions Compression at the fracture site could be impeded by placing an excessively angulated off-axis derotation wire prior to insertion of the HCS. Clinical Relevance Our study adds a new detail to the optimal technique of HCS placement in scaphoid fractures to improve compression and fracture union.

Headless Compression Screw Fixation for Proximal Phalanx Fractures: A Biomechanical Study

Hand ◽  
2020 ◽  
pp. 155894472092664
Author(s):  
Lauren Fader ◽  
Luke Robinson ◽  
Michael Voor
Keyword(s):  
Screw Fixation ◽  
Proximal Phalanx ◽  
Biomechanical Study ◽  
Materials Testing ◽  
Compression Screw ◽  
Headless Compression Screw ◽  
Screw Length ◽  
Significant Difference ◽  
Flexion Extension ◽  
Bending Load

Background: Proximal phalanx fractures are common injuries of the hand with multiple treatment options. Intramedullary (IM) screw fixation has become more widely used, and early outcomes are promising. However, biomechanical data regarding this type of fixation are sparse. Methods: Two methods of IM screw fixation of proximal phalanx fractures were tested in cadaver specimens. All specimens were treated with a single antegrade headless compression screw, with half getting the addition of a blocking screw. To test the most common deforming force of flexion-extension, each phalanx was subjected to apex volar 3-point bending using the Materials Testing System test frame. Results: There was no significant difference in the stiffness of 3-point bending with single antegrade screws alone and with a blocking screw (mean, 63.1 vs 52.2 N/mm; P = .27). When comparing smaller with larger specimens, stiffness of the small group was significantly greater than that of the large group when both fixation methods were included (85.3 vs 30.1 N/mm; P < .0002). When comparing stiffness with percent fill of the screw within bone, there was a moderately positive correlation (0.51). Conclusions: Addition of a blocking screw did not increase the stability of the IM screw fixation construct for proximal phalanx fractures. When comparing specimen size, the smaller bones were stiffer under 3-point bending load, regardless of the type of fixation. In addition, those specimens that had a larger longitudinal screw length to bone length ratio were stiffer. These findings provide valuable information as techniques for IM screw fixation of proximal phalanx fractures continue to evolve.

scholarly journals The Headless Compression Screw – Technical challenges in scaphoid fracture fixation

2015 ◽  
Vol 12 ◽  
pp. S211-S216 ◽  
Author(s):  
Usman Ahmed ◽  
Shahbaz Malik ◽  
Michael David ◽  
Claire Simpson ◽  
Simon Tan ◽  
...  
Keyword(s):  
Fracture Fixation ◽  
Scaphoid Fracture ◽  
Compression Screw ◽  
Headless Compression Screw ◽  
Technical Challenges

scholarly journals Biomechanical Strength of Retrograde Fixation in Proximal Third Scaphoid Fractures

Hand ◽  
2018 ◽  
Vol 14 (6) ◽  
pp. 760-764 ◽  
Author(s):  
Charles A. Daly ◽  
Allison L. Boden ◽  
William C. Hutton ◽  
Michael B. Gottschalk
Keyword(s):  
Cyclic Loading ◽  
Scaphoid Fracture ◽  
Maximum Load ◽  
Vascular Supply ◽  
Proximal Pole ◽  
Wrist Fractures ◽  
Scaphoid Fractures ◽  
Screw Length ◽  
Load To Failure ◽  
Biomechanical Strength

Background: Current techniques for fixation of proximal pole scaphoid fractures utilize antegrade fixation via a dorsal approach endangering the delicate vascular supply of the dorsal scaphoid. Volar and dorsal approaches demonstrate equivalent clinical outcomes in scaphoid wrist fractures, but no study has evaluated the biomechanical strength for fractures of the proximal pole. This study compares biomechanical strength of antegrade and retrograde fixation for fractures of the proximal pole of the scaphoid. Methods: A simulated proximal pole scaphoid fracture was produced in 22 matched cadaveric scaphoids, which were then assigned randomly to either antegrade or retrograde fixation with a cannulated headless compression screw. Cyclic loading and load to failure testing were performed and screw length, number of cycles, and maximum load sustained were recorded. Results: There were no significant differences in average screw length (25.5 mm vs 25.6 mm, P = .934), average number of cyclic loading cycles (3738 vs 3847, P = .552), average load to failure (348 N vs 371 N, P = .357), and number of catastrophic failures observed between the antegrade and retrograde fixation groups (3 in each). Practical equivalence between the 2 groups was calculated and the 2 groups were demonstrated to be practically equivalent (upper threshold P = .010). Conclusions: For this model of proximal pole scaphoid wrist fractures, antegrade and retrograde screw configuration have been proven to be equivalent in terms of biomechanical strength. With further clinical study, we hope surgeons will be able to make their decision for fixation technique based on approaches to bone grafting, concern for tenuous blood supply, and surgeon preference without fear of poor biomechanical properties.

Single Versus Dual Headless Compression Screw Fixation of Scaphoid Nonunions: A Biomechanical Comparison

Hand ◽  
2021 ◽  
pp. 155894472097411
Author(s):  
Luke T. Nicholson ◽  
Kristen M. Sochol ◽  
Ali Azad ◽  
Ram Kiran Alluri ◽  
J. Ryan Hill ◽  
...  
Keyword(s):  
Screw Fixation ◽  
Qualitative Assessment ◽  
Secondary Outcome ◽  
Scaphoid Nonunion ◽  
Compression Screw ◽  
Single Screw ◽  
Headless Compression Screw ◽  
Significant Difference ◽  
Load To Failure ◽  
Headless Compression Screws

Background: Management of scaphoid nonunions with bone loss varies substantially. Commonly, internal fixation consists of a single headless compression screw. Recently, some authors have reported on the theoretical benefits of dual-screw fixation. We hypothesized that using 2 headless compression screws would impart improved stiffness over a single-screw construct. Methods: Using a cadaveric model, we compared biomechanical characteristics of a single tapered 3.5- to 3.6-mm headless compression screw with 2 tapered 2.5- to 2.8-mm headless compression screws in a scaphoid waist nonunion model. The primary outcome measurement was construct stiffness. Secondary outcome measurements included load at 1 and 2 mm of displacement, load to failure for each specimen, and qualitative assessment of mode of failure. Results: Stiffness during load to failure was not significantly different between single- and double-screw configurations ( P = .8). Load to failure demonstrated no statistically significant difference between single- and double-screw configurations. Using a qualitative assessment, the double-screw construct maintained rotational stability more than the single-screw construct ( P = .029). Conclusions: Single- and double-screw fixation constructs in a cadaveric scaphoid nonunion model demonstrate similar construct stiffness, load to failure, and load to 1- and 2-mm displacement. Modes of failure may differ between constructs and represent an area for further study. The theoretical benefit of dual-screw fixation should be weighed against the morphologic limitations to placing 2 screws in a scaphoid nonunion.

scholarly journals Metacarpal Bony Dimensions Related to Headless Compression Screw Sizes

2019 ◽  
Vol 12 (S 01) ◽  
pp. S39-S44
Author(s):  
Michael Okoli ◽  
Kevin Lutsky ◽  
Michael Rivlin ◽  
Brian Katt ◽  
Pedro Beredjiklian
Keyword(s):  
Computed Tomography ◽  
Fracture Fixation ◽  
Ct Scans ◽  
Compression Screw ◽  
Metacarpal Head ◽  
Headless Compression Screw ◽  
Metacarpal Bones ◽  
Headless Compression Screws ◽  
The Mean ◽  
Distal Aspect

Abstract Introduction The purpose of this study is to determine the radiographic dimensions of the finger metacarpals and to compare these measurements with headless compression screws commonly used for fracture fixation. Materials and Methods We analyzed computed tomography (CT) scans of the index, long, ring, and small metacarpal bones and measured the metacarpal length, distance from the isthmus to the metacarpal head, and intramedullary diameter of the isthmus. Metacarpals with previous fractures or hardware were excluded. We compared these dimensions with the size of several commercially available headless screws used for intramedullary fixation. Results A total of 223 metacarpals from 57 patients were analyzed. The index metacarpal was the longest, averaging 67.6 mm in length. The mean distance from the most distal aspect of the metacarpal head to the isthmus was 40.3, 39.5, 34.4, and 31 mm for the index, long, ring, and small metacarpals, respectively. The narrowest diameter of the isthmus was a mean of 2.6, 2.7, 2.3, and 3 mm for the index, long, ring, and small metacarpals, respectively. Of 33 commercially available screws, only 27% percent reached the isthmus of the index metacarpal followed by 42, 48, and 58% in the long, ring, and small metacarpals, respectively. Conclusion The index and long metacarpals are at a particular risk of screw mismatch given their relatively long lengths and narrow isthmus diameters.

scholarly journals Biomechanical stability of complex coronal plane fracture fixation of the capitellum

2021 ◽  
Author(s):  
Paul Borbas ◽  
Rafael Loucas ◽  
Marios Loucas ◽  
Maximilian Vetter ◽  
Simon Hofstede ◽  
...  
Keyword(s):  
Fracture Fixation ◽  
Ultimate Load ◽  
Locking Plate ◽  
Distal Humerus ◽  
Coronal Plane ◽  
Fixation Strength ◽  
Biomechanical Stability ◽  
Significant Difference ◽  
Load To Failure ◽  
Headless Compression Screws

Abstract Introduction Coronal plane fractures of the distal humerus are relatively rare and can be challenging to treat due to their complexity and intra-articular nature. There is no gold standard for surgical management of these complex fractures. The purpose of this study was to compare the biomechanical stability and strength of two different internal fixation techniques for complex coronal plane fractures of the capitellum with posterior comminution. Materials and methods Fourteen fresh frozen, age- and gender-matched cadaveric elbows were 3D-navigated osteotomized simulating a Dubberley type IIB fracture. Specimens were randomized into one of two treatment groups and stabilized with an anterior antiglide plate with additional anteroposterior cannulated headless compression screws (group antiGP + HCS) or a posterolateral distal humerus locking plate with lateral extension (group PLP). Cyclic testing was performed with 75 N over 2000 cycles and ultimately until construct failure. Data were analyzed for displacement, construct stiffness, and ultimate load to failure. Results There was no significant difference in displacement during 2000 cycles (p = 0.291), stiffness (310 vs. 347 N/mm; p = 0.612) or ultimate load to failure (649 ± 351 vs. 887 ± 187 N; p = 0.140) between the two groups. Conclusions Posterolateral distal humerus locking plate achieves equal biomechanical fixation strength as an anterior antiglide plate with additional anteroposterior cannulated headless compression screws for fracture fixation of complex coronal plane fractures of the capitellum. These results support the use of a posterolateral distal humerus locking plate considering the clinical advantages of less invasive surgery and extraarticular metalware. Level of evidence Biomechanical study.

scholarly journals Pediatric Scaphoid Nonunions: A Case Series, Review of the Literature, and Evidence-Based Guidelines

2019 ◽  
Vol 09 (01) ◽  
pp. 002-012 ◽  
Author(s):  
Kerstin Oestreich ◽  
Tatiana Umata Yoko Jacomel ◽  
Sami Hassan ◽  
Maxim David Horwitz ◽  
Tommy Roger Lindau
Keyword(s):  
Nonoperative Management ◽  
Pediatric Population ◽  
Scaphoid Fracture ◽  
Case Series ◽  
Fracture Site ◽  
X Rays ◽  
Review Of The Literature ◽  
Level Of Evidence ◽  
Scaphoid Fractures ◽  
Magnetic Resonance Imaging Mri

Abstract Background Scaphoid fractures represent less than 3% of hand and wrist fractures in the pediatric population. Nonunions are very rare. We present a case series (n = 18) of nonunions in skeletally immature children and adolescents. We further present a review of the literature on pediatric scaphoid nonunions. Materials and Methods We reviewed the literature by searching the main databases on pediatric scaphoid nonunions, but to identify factors that lead to nonunion, we also searched for databases on scaphoid fractures. Seventy articles were found for the period between 1961 and 2019, all with level 4/5 evidence. Results The nonunion rate of pediatric scaphoid fractures in the literature is on average 1.5%, occurring mostly as a result of missed or underdiagnosed injuries, similar to our presented case series. Half (n = 9) of the injuries in our case series were missed initial injuries, leading to scaphoid nonunions and half developed nonunions after initial treatment. We found excellent outcomes and with surgical and nonoperative management, with few complications. Not surprisingly, the duration of immobilization is longer with nonoperative management. Conclusions Based on the literature, we recommend a period of nonoperative management before surgery in undisplaced nonunions. In displaced nonunions, open reduction and internal fixation ± bone grafting is necessary. In pediatric scaphoid fractures, similar to adult cases, we identified that suspicious scaphoid fractures should be considered for initial immobilization, and repeat X-rays and early magnetic resonance imaging (MRI) or computed tomography (CT) scans should be considered at follow-up. Immobilization time and type of plaster should be appropriate in relation to the fracture site, similar to the adult scaphoid fracture. Level of Evidence This is a Level IV study.

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