Osteotomy has been practiced for centuries, from ancient civilizations to today’s era of precision surgery. While medical technology has advanced dramatically, the core idea, cutting bone through pressure and friction, has stayed much the same.
Surgeons have long relied on tools like saws, chisels, and drills. Effective as they are, these instruments can place heavy mechanical and thermal stress on bone, sometimes causing lasting tissue damage. The heat and force involved often smear bone debris across the surface, slowing healing and prolonging recovery.
In the future, lasers could join the surgeon’s toolbox, especially for highly precise cuts. Unlike traditional tools, lasers don’t exert mechanical pressure, which means they can minimize microcracks and allow for more specialized procedures, such as inserting custom-made, 3D‑printed joint implants.
Lasers are already common in soft‑tissue surgery, but in bone, they’ve been limited. Until now, cuts could only reach depths of 2–3 centimeters, far too shallow for something like joint replacement. One major challenge has been the shape of the laser beam itself.
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Researchers at the University of Basel have recently shown how to overcome this barrier. By testing different laser beam shapes, the researchers found that a “top hat” profile made bone cutting far more effective than the traditional Gaussian shape. On bovine femur bone with optimized cooling, the top hat beam cut as deep as 44.5 mm at a speed of 0.42 mm/s, almost twice the depth and speed of the Gaussian beam.
Ferda Canba said, “Increasing the energy of the laser beam would not be a good solution. This could char the bone, negatively affecting the healing process. That’s why we changed the shape of the laser, or rather its profile.”
Think of a flashlight beam: brightest in the center, fading outward. That’s how a traditional Gaussian laser profile works; its energy peaks in the middle and tapers off smoothly. The new “top hat” profile, by contrast, flattens the peak so the energy spreads evenly across the beam, then drops sharply at the edges.
“Because the energy is transmitted more evenly, the laser cuts more efficiently and faster,” explained first author Mingyi Liu.
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To test the two profiles, the team used bovine bone and kept it cool with compressed air and water to prevent heat damage. The difference was clear. The traditional Gaussian beam cut about 2.6 centimeters deep. In contrast, the new top hat profile reached 4.4 centimeters, which is almost twice as deep.
In dry surface ablation, the top hat profile achieved cutting speeds of 1.58 mm/s (±0.04 mm/s). However, this did lead to more carbonization. Still, the depth was over twice that of previous Er:YAG laser results under optimized conditions. This gets the technique closer to the flat cut dimensions needed for procedures like distal femur resurfacing in total knee arthroplasty (TKA).
“A key factor for cutting efficiency is the fact that with the conventional laser profile, the walls of the cut absorb part of the energy. At a certain depth, the energy at the bottom of the cut is not sufficient to cut any deeper.”
“The top hat profile overcomes this problem because the energy in the beam is distributed differently and thus isn’t consumed by the walls of the cut.”
Scanning electron microscopy and Raman analysis confirmed that the laser left only minimal changes in bone composition, indicating very little thermal damage. To better understand the process, the researchers also used a steady‑state model to calculate the theoretical maximum ablation depth.
Taken together, the results show clear improvements when using the top hat profile in Er:YAG laser systems. By cutting deeper and faster while keeping bone damage minimal, this approach moves closer to real clinical use and could reshape procedures like joint resurfacing and implant placement.
Canbaz explained, “As part of the next steps, we will also need to investigate how we can adapt the system to the more complex situation in the body. There, it is also about protecting the surrounding tissue.”
Journal Reference:
- Liu, M., Hamidi, A., Blaser, D. et al. Influence of laser beam intensity profile on deep bone ablation in laser osteotomy. Sci Rep 16, 7101 (2026). DOI: 10.1038/s41598-026-37117-6
