Ultrasonic bone scalpels and the art of spine surgery — 2 leading neurosurgeons weigh in

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Historically, pneumatic drills have been the bone- cutting tool of choice for surgeons performing spine procedures. Ultrasonic bone scalpels, however, have elevated the art of bone removal. Neurosurgeons can now perform complex surgeries with incredible precision and accuracy, reducing blood loss and increasing patient safety.

Becker’s Spine Review recently spoke with two experts about their experience using ultrasonic tools for spine surgery and their predictions about the future of ultrasonics in their field:

  • Kai Ming Gregory Fu, MD, PhD, neurosurgeon with Weill Cornell Medicine Brain and Spine Center in New York City
  • Nicholas Theodore, MD, director of the Neurosurgical Spine Center and a professor of neurosurgery at Johns Hopkins Medicine in Baltimore

Ultrasonic bone scalpels are changing the game for surgeons
For decades, pneumatic drills have been the standard for high-speed removal of bone during spine surgeries. Although these tools are effective, they also have some drawbacks.

"For years, there haven’t been significant changes in the pneumatic drill except for new hand pieces and new drill bits," Dr. Theodore said. "It’s still a high-velocity instrument that removes bone quickly and it’s a little bit messy. There’s often bone dust and other material flying around."

Another concern is the unintentional removal of too much bone. Regular pneumatic drills can be hard to control because there is a lot of torque involved. It’s not uncommon for drills to skip and move around. Lack of control is also a problem physicians encounter with the hand tools used in spinal surgeries.

"In the past, I used a couple of drill bits very frequently when performing laminectomies," Dr. Fu said. "With a drill, however, you can very readily damage the dura. I would also sometimes use an osteotome after making the initial cut. The osteotome ideally cracks the bone where you want to crack it, but it’s an uncontrolled force."

According to Dr. Theodore, ultrasonics have elevated the art of bone removal. Instead of vaporizing bone with a drill, surgeons can now use an ultrasonic tool like a MisonixBoneScalpel. 

"The term ‘scalpel’ is key. This ultrasonic device is matched to the correct frequency and cuts through bone in a very precise way," Dr. Theodore said. "I can make bone cuts with incredible precision without worrying about thinning the bone out or destroying bone." 

When Dr. Theodore performs a laminectomy in the cervical spine, he makes two straight surgical cuts through the bone within a minute and removes the piece of bone. The ultrasonic bone scalpel also supports precise cuts for scoliosis surgery, osteotomies and en bloc tumor resections. 

"Bone scalpels give us the opportunity to make beautiful cuts and respect the human anatomy," Dr. Theodore said. "The other interesting thing is that there is much less bone bleeding. As we are drilling and get into the cancellous, the heat from the bone scalpel coagulates the surface and reduces blood loss."

Dr. Fu has had similar positive experiences with the Misonix BoneScalpel. "I tried it a couple of years ago for my more complex operations, out of a desire for patient safety and efficacy," he said. "The Misonix allows for precision cutting and its strength is that you can use it pretty much as you would an osteotome, but it is much safer. Since the BoneScalpel doesn’t cut through dura easily, it’s also a lot safer than a drill."

After seeing the benefits of the ultrasonic bone scalpel, Dr. Fu began to use it on his simpler, degenerative cases, especially laminectomies and transforaminal lumbar interbody fusion procedures. The tool has dramatically changed his overall practice.

"With the Misonix BoneScalpel, I have found that laminectomy procedures are a completely different animal," Dr. Fu said. "What used to take an hour to an hour and a half, with a lot of drilling, now takes three cuts with the Misonix, a little bit of work to remove the ligamentous hypertrophy and then the case is done and there is no bleeding. Now I use the ultrasonic bone scalpel almost exclusively for these types of cases."

From an anatomic and a teaching perspective, Dr. Theodore feels that the Misonix BoneScalpel has raised the game when it comes to bone removal. "When you have a scalpel and you make an incision, you want to be accurate," he said. "The BoneScalpel enables us to make cuts where we couldn’t before and it teaches the residents to make thoughtful cuts as they remove a chunk of bone."

Paired ultrasonic and robotic technology could transform the future of spine surgery
Looking ahead, both Dr. Theodore and Dr. Fu anticipate ultrasonic tools will be used in novel ways to improve the safety and efficiency of spine surgery. In the field of neurosurgery, tools based on ultrasonic technologies aren’t new. For years, neurosurgeons have used ultrasonic aspirators to treat tumors. They insert these devices into brain or spine tumors. The ultrasonic waves emitted from the tip vaporize and morselize the tumor. 

"Ultrasonic technology for bone cutting uses the same principles," Dr. Theodore said. "It uses sound waves to power the metal blade at a certain harmonic frequency that cuts through bone. What’s fascinating is that ultrasound opens up tremendous possibilities in medicine. We can use it now for tumors and for bone. The next question is whether we could use it for soft tissue, like disc removal and things like that. I think the potential is definitely there."

Dr. Fu also believes the neurosurgery field is in the early stages of what it can accomplish with ultrasonic tools. "The instruments we have today are a blade, but I think there could be even more unique, individualized tools designed for different processes which could make it much easier to perform surgeries of various types," he said.

Pairing ultrasonic tools with robotics appears to represent the next generation of spine surgery technologies on the horizon. "As we get more sophisticated in spine surgery, we are becoming more precise in what we do," Dr. Theodore said. "We are now using image-guided surgery to navigate in the spine, just as we’ve done with brain surgery for the last 35 years. I can foresee a future where robotics and ultrasonic technologies are coupled together to harness the power and precision of robotic positioning to make very precise cuts in the bone." 

Dr. Fu also believes that robotics will be the next step in advancing the use of ultrasonics during spine surgery. "I could envision a day where a robot will control where you want to make the cut and the cut can be made very precisely,” he said. “I think that would be a really great way to get higher levels of safety and reproducibility that would increase patient safety overall." 

Coupling high-precision ultrasonic bone cutting with high- precision robotics could lead to standardization of scoliosis procedures and minimally invasive spine procedures. By using ultrasound under the power of image guidance and robotic technology, neurosurgeons could remove bone in a safer and more accurate way.

Ultrasonic tools like the Misonix BoneScalpel enable neurosurgeons to perform complex surgeries more accurately and more rapidly. They also decrease patient blood loss in cases where surgeons must remove significant amounts of bone to reconstruct the spine. It seems, however, that the full potential of ultrasonic tools has only just started to be recognized in this clinical field.

"The adoption of new technology in the area of spine surgery has been exciting," Dr. Theodore said. "What’s encouraging now, as I train residents and talk to people across the world, is that these technologies significantly improve the safety and accuracy of procedures. I think the most exciting thing is coupling innovations, whether it’s ultrasound and robots or other technologies like robotics and imaging, to see what the next generation will have to offer patients undergoing spine surgery. I think it’s a very exciting time."

This article was sponsored by Misonix.

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