[Mechanical performance of non slotted small diameter nails of Gross and Kempf]. / Performances mécaniques des clous de tibia de Grosse et Kempf non fendus de faible diamètre.

The goal of this study was to evaluate the mechanical properties of closed section small diameter Grosse-Kempf tibia nails. This type of implant has been advocated for an unreamed nailing of open tibia fractures in order to avoid further damage of bone blood supply and an increased risk for compartment syndrome. Static and dynamic tests were performed on 9 and 10 mm nonslotted Grosse-Kempf (G-K) and Russel-Taylor (R-T) nails. Results were compared with the properties of a 11 mm slotted G-K nail, considered as the reference nail. Axial loading tests were realized on nailed cadaver tibiae after resection of a midshaft bone segment. 3 points bending tests have shown a mean diminution of the elastic limit of 50 per cent, and a 25 per cent decrease of the bending rigidity for the closed section nails, as compared with the slotted reference nail. The rigidity in torsion was on the other hand 10 times higher with the nonslotted nails, which is a direct consequence of the elimination of the slot. Axial loading tests performed on isolated implants have given comparable results for all types of nails, including the reference nail. Nailed tibiae axially loaded demonstrated a stable bone-implant interface for loads up to 200 daN, with a mean displacement of 2 mm for a 50 daN load, whatever the type of the nail. Bending tests achieved on locking screws have indicated that G-K screws are twice as rigid as R-T screws.(ABSTRACT TRUNCATED AT 250 WORDS)

In vivo determination of long bone flexibility--the epiphyses influence.

A lot of studies are devoted to the in vivo vibration analysis of long bones. In general they compare mechanical parameters relative to two instrumented bones or to one bone considered in different configurations. In this study a method of E. I product numerical determination is presented including for the first time the epiphysis influence in the calculation. The calculation of the maximum bending yield limit of the bone is carried out using this parameter. A method is proposed to determine the ultimate bending moment and the bone in vivo rigidity.