Really there’s 3 different categories of lengthening devices. You have your solely external fixators, you have the advanced internal nails or plates and you have the hybrid versions.Well let’s just say that people way smarter than me are working to improve it every day. Perhaps there may be a new internal device coming really soon. And perhaps there’s also research groups out there who want to develop a less invasive, less painful and more cost-effective method all together?
So first up...
The original limb lengthening technology is none other than the classic external ring fixator like the Ilizarov, and nowadays, the more common Taylor Spatial Frame, which is a hexapod-cylindrical outer-space looking metal frame that has 6 telescopic struts to help lengthen and or correct deformities with ease. The metal pins go through your soft tissue to lock into your bone where you can then turn the knobs to distract and gain length in the bone.
These circular external fixators are usually more applicable to the tibia of the lower leg due to their size, and even then, they’re still a bit heavy & cumbersome with a greater potential for infection if the pin sites aren’t kept clean.
With all that said they’re still the go-to device for those with severe deformities from trauma or birth defects, but they work just as well to lengthen bones.
These are uni-planar frames that also have metal pins that insert into the bone from the outside and are more appropriate for use on the femurs or for those with conditions requiring arm lengthening.
Alright next up…
These telescopic internal rods are the latest and greatest in limb lengthening technology as they are inserted directly into the medullary canal of your bones at which point they are locked into place with screws and distracted to lengthen the bone.
Although there are many variations, the most advanced are the magnetized lengthening rods like the titanium PRECICE nail. There have been several advancements in this nail alone from versions 1 to 2 to 2.1 to 2.2 to the most recent stainless steel version, The PRECICE-STRYDE aka The Stryde nail which is so amazing it allows for full weight bearing immediately post-op. But don’t be reckless and still be cautious when moving around.
These internal nails are fantastic for those with limb length discrepancies, stature lengthening for those with achondroplasia or hypochondroplasia, the two most common forms of dwarfism, and of course those interested in the cosmetic aspect of limb lengthening to get taller.
Now comes the combo method of lengthening devices.
The LON and LATN both require two surgeries for completion. Simply put, they were developed as a combination of an external fixator alongside an internal rod to reduce the amount of time needed to wear the external frame.
First, a standard (non-telescopic) internal nail is implanted inside the bone and the external fixator is put on. Then comes the lengthening phase via an external fixator. After distraction is complete, the nail is fully locked in place to maintain that length, at which time the external frame is taken off. Finally you just let the bone heal as normal with the rod inside.
The LATN method is similar, only difference being that in the first procedure, only the external frame is used to gain the desired length after which the standard internal nail is implanted to hold bone in place for consolidation healing and the external frame removed.
So then comes the question...Which of these lengthening methods is more effective?
Well the external fixators are best for deformity correction but can also be used for lengthening. But if your only goal is to get taller or fix a leg length discrepancy, then the internal nail will win out a majority of the time.
The benefits of internals simply outclass the externals in the following ways.
The only real drawbacks being that these internal devices are much more costly than externals. So if price is a factor in your decision process, an external fixator could be a solution for you.
So we’ve gone from only externals to a mix of externals and internals to only internals. Where next. How does LL technology advance from here on out?
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By: Victor Egonu
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