[Biomechanical studies on fracture fixation mechanism of the clover leaf medullary nail].
The intramedullary nailing method described by Küntscher is used widely now as an excellent treatment of the fracture of the long bone. However, it is well known from clinical experience that fracture fixation of the clover leaf nail is not so strong and especially rotational fixation is very poor. For the purpose of re-evaluating fracture fixation mechanism with Küntscher's nail, the following studies were performed. Osteotomized human cadaveric femur was fixed with the clover leaf nail in an ordinary manner. This osteosynthesis model was imbedded in plastic resin (RIGOLAC) in situ. Afterwards this model was cut into specimens 1.5 cm in thickness. The contact area between the bone and the nail was investigated macroscopically and roentgenographically on each specimen. Stress distribution in cross section of some commercially available clover leaf nails was investigated by the technique of photoelastography. Total expansive force of the clover leaf nail was obtained by the calculation based on the measured values. From these investigations the author concludes that the clover leaf nail does not fix the fracture by the expansive spring mechanism only, as was originally claimed by Küntscher.
D001696:Biomechanical Phenomena; D001858:Bone Nails; D004548:Elasticity; D005069:Evaluation Studies as Topic; D005260:Female; D005264:Femoral Fractures / Q000628:therapy; D005594:Fracture Fixation, Intramedullary / Q000379:methods*; D006801:Humans; D008297:Male; D008875:Middle Aged; D013314:Stress, Mechanical