Traditional orthopedic surgery relies heavily on mechanical tools such as saws, chisels, and drills to cut bones. Although these devices are reliable, they create significant friction and mechanical stress that can damage surrounding tissue and prolong patient recovery.^.

In search of a gentler alternative, medical engineers have long investigated laser technology. The laser works without physical contact, which eliminates mechanical pressure and minimizes the risk of microcracks in the bone. This level of precision is ideal for specialized procedures such as inserting highly customized 3D printed joint implants.

However, adapting lasers to hard tissues has proven difficult. Although surgical lasers effectively cut soft tissue, penetrating dense bone remains a major challenge.

Until recently, laser osteotomy could only achieve shallow cuts of up to 3 centimeters. This depth is severely lacking for major orthopedic surgeries such as total knee arthroplasty, which require a planar incision approximately 6 centimeters deep.

flatten the beam

Restrictions are not just a matter of power. “Increasing the energy of the laser beam is not a good solution; this can scorch the bone and negatively affect the healing process,” explains Dr Felda Kambas from the University of Basel.

Instead of turning up the dial, the team changed the basic shape of the laser. conventional surgical laser Er:YAGsimilar to a standard flashlight, is strongest in the center and dims towards the edges. When this uneven beam cuts into the bone, it carves a V-shaped groove.

As the cut deepens, the V-shape causes the beam to lose focus and energy density. This acts like a light funnel, eventually cutting off the beam’s energy completely.

To get around this barrier, the researchers flattened the beam into a uniform “top hat” shape. This redesigned beam spreads its energy evenly across its width before attenuating sharply at the edges.

“Lasers cut more efficiently and faster because the energy is transferred more evenly,” says Mingyi Liu, a doctoral student and first author. By maintaining a flat bottom, the laser ablates straight down, preventing the trench walls from taking away strength and unlocking deeper penetration.

A new era of joint implants

The research team tested the reshaped Er:YAG laser on thick bovine femur bones. To prevent tissue charring, the bones were continuously cooled with water microjet and compressed air jets. The results were recently published in a magazine scientific reportwe are making great progress.

Traditional Gaussian lasers stalled at a depth of about 2.6 centimeters (almost 1 inch), whereas the top hat profile sliced ​​down to 4.45 centimeters. This brings the technique significantly closer to the dimensions required for large-scale joint resurfacing surgery. Furthermore, microscopic analysis confirmed that the cellular network of the bone remained intact and healthy right up to the edge of the cut.

But laser blades have yet to banish mechanical saws from operating rooms. Speed ​​of cutting remains a stubborn hurdle^.

Currently, top-hat lasers remove approximately 0.42 cubic millimeters of bone per second. In contrast, traditional oscillating saws remove approximately 11 cubic millimeters per second. This is almost 25 times faster.

Despite this gap in surgical time, the unprecedented depth achieved by the team paves a realistic path to mainstream clinical use. Researchers are now focused on improving the robotic delivery system to living vascularized tissue.

“As part of the next steps, we also need to investigate how to adapt the system to more complex situations within the body, where it is also important to protect the surrounding tissues,” explains Dr Felda Kambas.