Abstract
Introduction-Aim: The fractures which occurred at the midshaft of the femur, in which there is a prosthesis, are difficult to stabilize using free screws or plates, because of the presence of the underlying intramedullary stem, PMMA cement and thin periprosthetic femoral cortex. Although the periprosthetic fractures are usually oblique with a big contact surface between the pieces of the fracture and with the datum of the intramedullary presence of the femoral stem of the prosthesis, which increases the stability, this study compares five different types of internal fixation a rather unstable «worst case scenario» oblique midshaft fracture of the femur.
Material & Methods: We compared «in vitro» the mechanical performance of five different ïsteosynthesis techniques applied on a oak femoral model obliquely oscillated to mimic a short oblique 60o fracture. We compared the following kind of osteosynthesis: (a) double stainless steel wiring, (b) two 4.5 mm lag screws, (c) combination of one 4,5 mm cortical screw and one stainless steel wire, (d) double CCG cerclage, and (e) one titanium cerclage CCG (Compression Cerclage Gudolf) combined with one 4.5 mm screw. The five fixation constructs were subjected to a noncyclic destructive axial compression and torsional loading.
Results: The highest torque stiffness showed the double CCG and the double screw constructs, followed by the combination of CCG-screw and double wire constructs. The mode of failure in torque was a longitudinal crack close to the screw tip and loosening of CCG and wire. The double screw, double CCG and screw-CCG constructs provided the highest stiffness in axial compressive forces. The mode of failure in compression was loosening of CCG and wire and bending of screw.
Conclusions: The advantages of using the CCG is the simple technique, biocomptability of titanium, no interference in modern imaging techniques and avoidance of stripping of muscles. The method with the CCG titanium band proved biomechanically so stable as the system with the double 4,5 mm screw and recommend an alternative solution for the osteosynthesis of the distal periprosthetic fractures of the femur, especially for the cases with periprosthetic osteoporosis.
The abstracts were prepared by Eleni Koutsoukou. Correspondence should be addressed to him at the Hellenic Association of Orthopaedic Surgery and Traumatology (HAOST), 20, A. Fleming str, 15123 Marousi, Athens, Greece.
