28/11/2006
AO Technical Commission Approved

Distal Femoral Nail with Spiral Blade

In the past years, retrograde femoral nailing has proven to be safe and reliable. The Distal Femoral Nail is becoming increasingly popular and is especially suitable for obese (or pregnant) patients and in osteoporotic metaphyseal bone.

Indications include extra-articular metaphyseal distal femoral fractures (32-A1 to C3) and supracondylar fractures and simple articular fractures (33-A1 to A3 and 33-C1 to C3.1).

The Spiral Blade enables significantly more stable distal interlocking than with conventional locking bolts due to the large load-bearing surface. It reduces cancellous bone compaction and lowers the risk of nail protrusion into the knee joint. The nail diameters are 9.0 and 10.0 mm for solid nails and 12.0 mm for cannulated nails.

Lengths range from 160 to 420mm.

A Scientific Study from the AO Research Institute

Objective: Intramedullary nail locking bolts often fail to gain purchase or cut out in osteoporotic bone. The biomechanical stability of a bladelike device that lowers intraosseous stress levels by distributing the load over a greater volume of bone was compared with conventional locking bolts in osteoporotic bone.

Methods: Standardized simulated comminuted supracondylar femoral fractures (segmental defect) in fresh-frozen paired osteoporotic (bone mineral density <200 milligrams per cubic centimeter) human cadaveric femurs were stabilized with a retrograde unreamed distal femoral nail and distally interlocked with conventional locking bolts or a bladelike device. The distal portions of the fixator-bone constructs were tested under axial load, and the stiffness and strength were compared (pairwise).

Results: Interlocking with a bladelike device was 41 percent stiffer (p = 0.01) and 20 percent stronger (p = 0.02) than that with conventional locking bolts. All posttesting radiographs showed compaction of the cancellous bone distal to the interlocking devices. Even after nail displacements of twelve millimeters, only a few locking bolts were plastically deformed and no bladelike device showed gross plastic deformation.

Conclusion: This study showed the biomechanical benefits of increasing the bone-implant interface surface for improving the acute stiffness and strength of fracture fixation in osteoporotic cancellous bone. The fixator-bone construct withstood higher forces before failure in these fragile bones.


Additional Nail Lengths and 6.0 mm Ti Locking Screws

The Titanium Distal Femoral Nail (DFN) is now available in additional sizes of 180 mm, 220 mm, and 260 mm, in all diameters, to better accommodate patients anatomy.

The existing 6.0 mm Ti Locking Screw line has been extended with sizes 30 mm, 35 mm, and 40 mm for smaller patients.

 

Female, 88 years

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Due to varying countries’ legal and regulatory approval requirements, consult the appropriate local product labeling for approved intended use of the products described on this website. All devices on this website are approved by the AO Technical Commission. For logistical reasons, these devices may not be available in all countries worldwide at the date of publication. 


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