Me: I found this article when I was searching for more information on bone lengthening. It seems that the engineering students in this generation are trying their hands and finding better ways to do limb lengthening. What makes this so interesting is that the device they have as a prototype is a combination of the efforts of students in biomedical engineering and mechanical engineering. The device does the distraction of the bones by attaching to the wires that goes through the bone in the external fixator method and slowly moves the wires apart from each other while still keeping the overall structure stable. The unique thing they have is the feedback mechanism which makes sure the device does not overdo a distraction.
From website GizMag HERE
Students create automated bone-lengthening device
By Randolph Jonsson April 25, 2012
Whether it’s from injury, infection or malfunctioning genes, millions of children suffer from bone deformities at any given time. To help remedy the situation, doctors often resort to the painful practice of breaking the target bone and then repeatedly moving the ends apart as they attempt to grow together – a procedure known as distraction osteogenesis (DO), that has its share of risks and problems. Now, a team of undergrad students from Rice University (RU) in Texas has come up with a device they hope will make the lengthy process of bone-stretching both easier and safer for the young patients who have to endure it.
“The process of limb lengthening – essentially creating a localized mini-growth spurt – works well for bones, but is very hard on the soft tissues such as nerves and blood vessels,” Gogola said. “This team has done an outstanding job of designing a creative solution. Their device not only protects the soft tissues, it will ultimately speed up the entire process.”
With current DO rigs, long pins are embedded on both sides of the break in the bone to be lengthened. These are then attached to a bulky threaded frame outside of the appendage with a drive screw that must be regularly adjusted manually several times a day with a hex wrench. This pushes the pins further apart as the bone heals, but before it sets, allowing the gentle elongation of the bone over a period of several months. It’s a burdensome task for patient and caregiver alike.
X-ray images of various distraction osteogenesis rigs in place
“The problem with the current device is that there’s a lot of room for error,” RU team member Kahn said. “You can imagine that one might forget to turn it once, or turn it the wrong way, or turn it too much. And a lot of problems can arise in the soft tissue and the nerves surrounding the bone,” she added. “That’s the limiting factor of this process. But LinDi implements a motor to make the distraction process nearly continuous.”
In fact, the battery-powered LinDi self-adjusts about 1,000 times a day, which allows it to better approximate bone growth. The team’s innovative inclusion of a force-feedback sensor – a first for DO devices – monitors stress loads on surrounding tissues and shuts the system down if levels get too high, thus averting unnecessary trauma from the process.
Short-term animal testing with the help of Shriners hospital staff allowed the students to fine tune the device and confirmed that it works as planned – a nice feather in the bonnet of the soon-to-be grads and a welcome relief for the countless children and their parents who stand to benefit from this new technology in the years to come.
Me: One a related note one of the commenters made a point that there was alreday a company in the 90s which had already developed a very similar device that could automate the distraction / stretching of the bone process. However there was no feedback mechanism that told the Automator to stop when the bone is distracted too far. From the comments on the article above…
“”A friend of mine did this nearly 15 years ago while working for a company called Autogenisys they automated the Ilizarov apparatus. While they they didn’t have a feed back system you didn’t have to manually adjust it either.””
25th April, 2012 @ 09:40 pm PDT
Autogenesis Website link HERE
From the website….
- Ring Frame Lengthening
- Bone Transport
- Unilateral Frame Lengthening
- Joint Contracture
- Angular Deformity Correction.
Research indicates that frequent distractions in small increments can promote superior muscle tissue and reduce the forces required to accomplish distraction (thereby reducing pain experienced by the patient). The Automator performs precise micro-distractions every few minutes minutes rather than every six hours as is typical with manual systems. Hence, the lengthening process is more similar to the body’s natural (continuous) growth process. Additionally patients and their families report less anxiety.
The Automator was designed to provide an improved automated alternative to manual distraction methods. The device:
- Costs the same or less than most manual distracters sold by large medical equipment manufacturers,
- Allows patients to enjoy the psychological and physical benefits of high rhythm (small increment) corrections,
- Allows for precision, flexibility, and reliability unavailable with manual systems, and
- Does not introduce installation or operational complexity to the procedure.
Automated lengthening should be the standard of care for limb lengthening and deformity correction procedures.
- Continuous Distraction: The Automator causes 1/240 mm adjustments 24 hrs per day according to the rate selected. Accuracy is maintained within 1/48 mm.
- Compact: The self contained design involves no external cables, batteries, or programming module. Each Automator weighs approximately 6oz.
- Programmable: Rate settings include 0.5, 0.75, 1.0, 1.25, 1.5, 2.0, and 4.0 mm/day. The device may be set for distraction, compression, or cyclical motion (used for loading a fracture site). Rate and directional settings may be changed by the physician at any time.
- Convenient: Brackets facilitate installation. The Automator is water resistant, and it requires minimal maintenance.
- Efficient: Automator batteries last more than four months when lengthening at 1mm per day. The device can distract against more than 250 lbs.
- Versatile: The device may be installed on ring or unilateral frames regardless of the distance between rings or frame components.