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Plate Positioning in Periprosthetic or Interprosthetic Femur Fractures With Stable Implants-A Biomechanical Study

Matthias G Walcher, Karlmeinrad Giesinger, Ryan Du Sart, Robert E Day & Markus S Kuster

Kurzfassung

BACKGROUND
Angular stable plate fixation is a widely accepted treatment option for interprosthetic or periprosthetic femoral fractures with stable implants. This biomechanical study tries to establish a safe distance of the plate from the tip of a femoral prosthesis.

METHODS
A total of 38 composite femurs were reamed to an inner diameter of 23 mm to create an osteoporotic bone model. A Weber hip stem was cemented into each and a distal femoral NCB plate applied with the distance to the stem varying from 8 cm apart to 6 cm overlap in 2-cm steps. Each specimen was tested in cyclic axial loading (400 N-1500 N) and then cyclic torsion (0.6 Nm-50 Nm). Peak strain on the femur around the tip of the plate was measured with a 3D image correlation system and averaged over 26 cycles (excluding the first 3 and the last cycles). Finally, each femur was axially loaded to failure.

RESULTS
Strain increased with decreasing overlap or gap. Seven specimens failed early between 2-cm overlap and 2-cm gap. Results were divided into a far group with a distance of >4 cm and a close group of <4 cm. Strain was significantly higher in the close group for axial (P < .001) and torsional (P < .001) loading. Failure load was significantly lower in the close group (P = .002).

CONCLUSION
A minimal gap and/or overlap of at least 6 cm is recommended in osteoporotic bone to avoid stress risers.
   
Zitation Walcher M G, Giesinger K, du Sart R, Day R E, Kuster M S. Plate Positioning in Periprosthetic or Interprosthetic Femur Fractures With Stable Implants-A Biomechanical Study. J Arthroplasty 2016; 31:2894-2899.
   
Typ Wissenschaftlicher Artikel/Review (Englisch)
Veröffentlichungsdatum 03-06-2016
Titel der Zeitschrift J Arthroplasty (31/12)
ISSN electronic 1532-8406
Seiten 2894-2899
PubMed 27381372
DOI 10.1016/j.arth.2016.05.060