Screw- versus plate-fixation strength of acetabular anterior column fractures: a biomechanical study.
BACKGROUND
The standard for operative treatment of acetabular fractures is open reduction and plate fixation. Recently, screw fixation-only methods through less invasive approaches are reported, but biomechanical data are missing. Questions posed in this study are (1) is the static fixation strength of different screw types equivalent to the standard plate fixation for anterior column fractures of the acetabulum? and (2) does the placement of an additional screw in the infra-acetabular corridor increase the fixation strength independent of the used implant?


METHODS
Three groups of different screws (group II, titanium; group III, stainless steel; and group IV, biodegradable Poly-L-Lactid) were compared with the standard plate fixation (group I) in Synbone pelves with custom-made anterior column fractures. Six pelvises per group were axial loaded with six cycles of 800 N, twice with and without an additional placed infra-acetabular screw.


RESULTS
The fixation strength of titanium screws was equivalent to the standard plate fixation. The stainless steel and Poly-L-Lactid screw fixation strengths were equivalent to each other but inferior to the aforementioned. The additional placement of an infra-acetabular screw significantly increased the fracture fixation strength, independent of the used implant.


CONCLUSIONS
Screw fixation is a promising alternative approach for the stabilization of noncomminuted acetabular fractures of the anterior column with equivalent fixation strength to the standard plate fixation. The additional placement of an infra-acetabular screw significantly increases the fracture fixation independent of the used implant and should be considered for acetabular fractures with separation of both columns.


METHODS
Therapeutic study, level IV.
Department of Trauma, Hand and Reconstructive Surgery, Friedrich Schiller University, Jena, Germany. marc.gras@med.uni-jena.de
Florian
F
Gras
Ivan
I
Marintschev
Christoph E
CE
Schwarz
Gunther O
GO
Hofmann
Tim
T
Pohlemann
Ulf
U
Culemann
D020341:Absorbable Implants; D000077:Acetabulum / Q000293:injuries / Q000601:surgery*; D001696:Biomechanical Phenomena; D001860:Bone Plates; D001863:Bone Screws; D019245:Compressive Strength; D016001:Confidence Intervals; D004867:Equipment Design; D004869:Equipment Safety; D005593:Fracture Fixation, Internal / Q000295:instrumentation* / Q000379:methods; D050723:Fractures, Bone / Q000000981:diagnostic imaging / Q000601:surgery*; D006801:Humans; D021621:Imaging, Three-Dimensional; D017145:Models, Educational; D011859:Radiography; D012680:Sensitivity and Specificity