Screw fixation of simulated scaphoid waist fractures: a biomechanical comparison of two screw lengths.
|Title||Screw fixation of simulated scaphoid waist fractures: a biomechanical comparison of two screw lengths.|
|Publication Type||Conference Abstract|
|Year of Publication||2017|
|Authors||M. Ouwendijk, N. Slingerland, J. van Nistelrooij, T. Huysmans, E. Van de Casteele, F. van Glabbeek, G. Meermans, and F. Verstreken|
|Conference Name||European Federation of National Associatinos of Orthopaedics and Traumatology (EFORT), 18th ANNUAL CONGRESS, VIENNA, AUSTRIA|
Objectives: The goal of this study was to compare the fixation strength for long and short screws in order to evaluate if the choice for the longer screw is worth the increased risk of protrusion.
Study design & methods: Thirteen pairs of fresh frozen cadaveric scaphoids were randomized to have one side fixed with a long and one with a shorter screw (longest screw possible and longest length minus 4 mm). Under fluoroscopic control a central guidewire was inserted and a cannulated screw placed. A wedge osteotomy was made to simulate a horizontal oblique fracture plane. The proximal pole of the scaphoid was placed into a fixture. Load was applied by using a load-controlled test protocol in a hydraulic testing machine and displacement was measured.
Results: There was no significant difference between the load at 1 and 2mm displacement for long and short screws. The load at 1 and 2 mm displacement was 40.9 N (SEM 7.0 N; 90% CI 28.4-53.5 N) and 80.9 N (SEM 11.0 N; 90% CI 61.1-100.7 N) for the short screws compared with 50.4 N (SEM 10.2 N; 32.0-68.8 N) and 92.6 N (SEM 15.6 N; 64.5-120.7 N) for the long screws. An equivalence test based on the mean and 90% CI showed that these values are equivalent.
Conclusions: These data suggest that in oblique waist fracture, fixation with a long or a short screw are equivalent in strength. Given the higher risk of complications with longer screws, a shorter screw is advisable and has no negative impact on the stability of the construct.