The Marchetti bundle nail for femoral shaft fractures: a review of 56 cases

Mechanical Behavior of Elastic Self-Locking Nails for Intramedullary Fracture Fixation: A Numerical Analysis of Innovative Nail Designs

Intramedullary nails constitute a viable alternative to extramedullary fixation devices; their use is growing in recent years, especially with reference to self-locking nails. Different designs are available, and it is not trivial to foresee the respective in vivo performances and to provide clinical indications in relation to the type of bone and fracture. In this work a numerical methodology was set up and validated in order to compare the mechanical behavior of two new nailing device concepts with one already used in clinic. In detail, three different nails were studied: (1) the Marchetti-Vicenzi's nail (MV₁), (2) a revised concept of this device (MV₂), and (3) a new Terzini-Putame's nail (TP) concept. Firstly, the mechanical behavior of the MV₁ device was assessed through experimental loading tests employing a 3D-printed component aimed at reproducing the bone geometry inside which the device is implanted. In the next step, the respective numerical model was created, based on a multibody approach including flexible parts, and this model was validated against the previously obtained experimental results. Finally, numerical models of the MV₂ and TP concepts were implemented and compared with the MV₁ nail, focusing the attention on the response of all devices to compression, tension, bending, and torsion. A stability index (SI) was defined to quantify the mechanical stability provided to the nail-bone assembly by the elastic self-locking mechanism for the various loading conditions. In addition, results in terms of nail-bone assembly stiffness, computed from force/moment vs. displacement/rotation curves, were presented and discussed. Findings revealed that numerical models were able to provide good estimates of load vs. displacement curves. The TP nail concept proved to be able to generate a significantly higher SI (27 N for MV₁ vs. 380 N for TP) and a greater stiffening action (up to a stiffness difference for bending load that ranges from 370 Nmm/° for MV₁ to 1,532 Nmm/° for TP) than the other two devices which showed similar performances. On the whole, a demonstration was given of information which can be obtained from numerical simulations of expandable fixation devices.

The Marchetti-Vincenzi humeral nail--a useful device in fresh fractures

Whilst most humeral fractures may be treated by closed methods, humeral nailing has gained popularity where a surgical option is indicated. Concern has been expressed regarding placement of proximal and distal locking screws whilst the efficiency of the ingenious intra-medullary locking device of the Seidel nail has also been questioned. The Marchetti-Vincenzi nail, which "locks" proximally with the spreading of intra-medullary pins and distally with a single screw inserted via the surgical wound, apparently avoids potential neurovascular and tendon injury. Prospectively recorded data was analysed in 19 "fresh" fractures, i.e. within 3 weeks of injury, and in 13 "late" fractures (total of 32 humeral fractures) treated with the Marchetti nail. All fresh fractures thus treated progressed to union, whilst in the late fracture group there were three non-unions all of whom were in osteoprotic females. Whilst we commend the use of the Marchetti humeral nail in fresh fractures, we have reservations about its use in "late" fractures particularly where the patient is female and osteoporotic.

Fixation of femoral shaft fractures with a flexible bundle-type nail

In a prospective study, 31 consecutive patients with a femoral shaft fracture were treated with the Marchetti-Vicenzi intramedullary flexible bundle-type nail. Open reduction of the fracture was necessary in 25 of the 31 patients (81%). Twenty-five of the 31 fractures (81%) united within 2.5 to 6 months after the operation (mean, 4.2 months). Nonunion occurred in one patient (3.2%). Other complications included delayed union in five patients (16%), femoral shortening in five (16%), breakage of the distal pins in two (6.5%), and severe varus malunion in two patients (6.5%). Because of the high complication rate in this series, the authors no longer use the Marchetti-Vicenzi flexible nail for treatment of femoral shaft fractures.