Document Detail

Screw fixation of scaphoid fractures: a biomechanical assessment of screw length and screw augmentation.
MedLine Citation:
PMID:  16516734     Owner:  NLM     Status:  MEDLINE    
PURPOSE: To assess the biomechanical stability relative to screw length and K-wire augmentation in scaphoid fracture fixation using a flexibility testing protocol and cadaver scaphoids whose soft tissue attachments remained undisturbed. Our hypothesis was 2-fold: increasing screw length and augmenting fixation with a K-wire would improve fracture fragment stability, individually and in combination. METHODS: Flexion and extension loading applied through wrist tendons was performed on 10 cadaveric wrists after volar wedge scaphoid osteotomy and internal fixation. Each wrist participated in 3 experimental groups: short screw, long screw, and long screw augmented with a K-wire transfixing the distal pole to the capitate. Interfragmentary displacements were measured. RESULTS: Analysis of variance showed significantly less fracture fragment motion with longer screws than with short screws in 4 of the 6 displacement axes. The flexion/extension axis rotations for the short, long, and augmented long-screw groups were 8.2 degrees +/- 4.8 degrees, 3.9 degrees +/- 1.6 degrees, and 1.8 degrees +/- 1.3 degrees, respectively. Although K-wire augmentation reduced displacement of the fracture fragments it did not decrease interfragmentary motion significantly when compared with the long-screw group. CONCLUSIONS: Under physiologically applied loading of cadaveric wrists with unstable scaphoid waist fractures the long screw provided significantly greater stability than the short screw. Although K-wire augmentation in the long-screw group did improve stability the improvements were not significant. Based in part on the biomechanical data from this study it is our recommendation that the optimally placed screw for scaphoid fracture fixation stability is a long screw positioned down the central axis of the scaphoid deep into subchondral bone.
Seth D Dodds; Manohar M Panjabi; Joseph F Slade
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  The Journal of hand surgery     Volume:  31     ISSN:  0363-5023     ISO Abbreviation:  J Hand Surg Am     Publication Date:  2006 Mar 
Date Detail:
Created Date:  2006-03-06     Completed Date:  2006-07-20     Revised Date:  2009-06-08    
Medline Journal Info:
Nlm Unique ID:  7609631     Medline TA:  J Hand Surg Am     Country:  United States    
Other Details:
Languages:  eng     Pagination:  405-13     Citation Subset:  IM    
Department of Orthopaedics and Rehabilitation, Yale University School of Medicine, New Haven, CT 06520, USA.
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MeSH Terms
Aged, 80 and over
Bone Screws*
Bone Wires
Fracture Fixation, Internal / instrumentation*,  methods*
Fractures, Bone / physiopathology,  surgery*
Joint Instability / physiopathology,  surgery
Pronation / physiology
Prosthesis Design
Range of Motion, Articular / physiology
Scaphoid Bone / injuries,  physiopathology,  surgery*
Supination / physiology
Weight-Bearing / physiology
Wrist Joint / physiopathology,  surgery

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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