Rotational Stability of Scaphoid Osteosyntheses: An In Vitro Comparison of Small Fragment Cannulated Screws to Novel Bone Screw Sets

Erhart, Jochen; Unger, Ewald; Schefzig, Philip; Варга, П.; Trulson, Inga; Gormasz, Anna; Trulson, Alexander; Reschl, Martin; Hagmann, Michael; Vécsei, V.; Mayr, Winfried

doi:10.1371/journal.pone.0156080

Cited by 11 publications

(7 citation statements)

References 31 publications

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“…However, Buetel tried to explain this contradictory result indicating that the screws used in the double screw combination were thin (1.5 mm). [9,10] Similar to the results of the study by Jurkowitsch et al, [9] the results of the current study showed that double screw fixation was superior to single screw in respect of both displacement and rotation. Although the diameter of the single screw is thicker than the double screw's, it has been shown to be weaker than two thin screws, particularly against rotational forces.…”

Section: Discussionsupporting

confidence: 89%

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Single versus double screw fixation for the treatment of scaphoid waist fractures: Finite element analysis and preliminary clinical results in scaphoid nonunion

et al. 2020

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This study aims to compare the single versus double screw fixation of scaphoid waist fractures using finite element analysis, and to present the preliminary clinical results of double screw fixation in a consecutive series of patients with scaphoid nonunion. Patients and methods: A transverse scaphoid waist fracture (Herbert type B2) model was fixed with either single or double cannulated compression screws. Displacement and rotation of the fragments were performed using three-dimensional finite element analysis in three different wrist positions. A retrospective review was performed on 13 male patients (mean age 31.6±12.8 years; range, 17 to 64 years) who underwent double screw fixation for an established scaphoid nonunion in our clinic between January 2015 and December 2017. Assessment of union was established with serial plain radiographs in eight patients and with wrist computed tomography in five patients. Clinical evaluation was performed using the Mayo wrist score and visual analog scale (VAS). Results: In all wrist positions, the displacement of the fracture gap in double screw fixation in all planes (x, y, and z) was less than in single screw fixation. Similarly, rotation of the fracture fragments around the longitudinal axis of the scaphoid was lower in double screw fixation. Complete union was obtained in all patients. The mean time to union was 5±0.75 months (range, 4 to 6 months). The mean VAS was 0.8±0.9 (range, 0 to 3). Mayo wrist score was 91±6.9 (range, 80 to 100) at the final follow-up. Conclusion: Double-screw fixation technique may be a solution to reduce the rate of scaphoid nonunion in unstable type B2 scaphoid fractures or nonunion.

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Section: Discussionsupporting

confidence: 89%

“…Biomechanical and clinical studies have shown that newly-developed scaphoid plates provide more stable fixation. [8,9] In addition, Erhart et al [10] have developed new anti-rotational screws particularly designed for scaphoid fractures.…”

mentioning

confidence: 99%

Single versus double screw fixation for the treatment of scaphoid waist fractures: Finite element analysis and preliminary clinical results in scaphoid nonunion

et al. 2020

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“…14 In addition, some of these studies only provided a vague idea of the efficacy of an in vivo osteosynthesis and thus, the use of specific screws still relies largely on availability, cost, and surgeon's preference. [15][16][17][18][19][20] The most prominent difference in the study was time to return to work between the two groups, favoring the operated group. A recent meta-analysis of four studies comparing operative (both open and percutaneous fixation) and conservative treatment of stable scaphoid fractures, reached the same conclusion.…”

Section: Discussionmentioning

confidence: 99%

Comparison of Minimally Invasive Operative Treatment with Conservative Treatment for Acute, Minimally Displaced Scaphoid Fractures at 12 Months' Follow-up

et al. 2021

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Background Minimally displaced scaphoid fractures can be challenging to diagnose and treat. Cannulated scaphoid screws have made percutaneous stabilization highly effective. Questions Would minimally invasive operative treatment of minimally displaced scaphoid fractures yield faster return to work when compared with patients treated conservatively? How do functional and patient satisfaction scores compare between the two groups at 12-months follow-up? Patients and Methods Records from 18 patients (mean age 28.6 years) treated surgically were retrospectively reviewed and compared with a group of 10 patients (mean age 33.3 years, p = 0.74) treated nonoperatively. Inclusion criteria were a minimum follow-up period of 12 months and radiographic union. Time to return to work was compared between groups. At 12 months' follow-up, wrist range of motion (ROM) and grip strength were compared, as well as pain, satisfaction, and overall wrist function were evaluated by the visual analogue scale (VAS) and the Mayo modified wrist score (MMWS). Results The mean time to return to work for the operated group was 39.75 days, while for the nonoperated group it was 88.14 days (p = 0.002). At the 12 months' follow-up, mean ROM, grip strength, and VAS score did not differ between groups. The mean MMWS was 98.75 for the operated group and 87.5 for the nonoperated group, indicating a better result in patients treated operatively (p = 0.03). In addition, two failures of instrumentation were recorded, a seldom seen complication. Conclusion Percutaneous fixation of minimally displaced scaphoid fractures allows faster return to work and leaves patients more satisfied with their wrist function compared with plaster immobilization at 12 months' follow-up. Level of evidence This is a Level III, retrospective, case–control study.

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“…Previous studies have utilized a similar bending moment as a 800 N/mm moment is thought to be a clinically relevant load. 19,20 The bending moment was applied with a cantilever load on the proximal aspect where the cantilever load applied to the scaphoid depended on the moment arm which was measured as the horizontal distance between the midpoint of the fracture site and the location where cantilever load was applied. The cantilever load was calculated by dividing the bending moment of 800 N/mm by the moment arm.…”

Section: Methodsmentioning

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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Rotational Stability of Scaphoid Osteosyntheses: An In Vitro Comparison of Small Fragment Cannulated Screws to Novel Bone Screw Sets

Cited by 11 publications

References 31 publications

Single versus double screw fixation for the treatment of scaphoid waist fractures: Finite element analysis and preliminary clinical results in scaphoid nonunion

Single versus double screw fixation for the treatment of scaphoid waist fractures: Finite element analysis and preliminary clinical results in scaphoid nonunion

Comparison of Minimally Invasive Operative Treatment with Conservative Treatment for Acute, Minimally Displaced Scaphoid Fractures at 12 Months' Follow-up

Impact of Screw Length on Proximal Scaphoid Fracture Biomechanics

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