Robotic Spine Surgery System and Methods Autonomous Screw Placement Guided by Thread Geometry

This patent describes a surgical robot for spine procedures that can drive a bone screw along a planned path and automatically coordinate how fast it turns and how fast it advances, using the screw’s own thread shape as a guide. It comes from MAKO Surgical Corp., the robotic surgery business owned by Stryker.

The Problem

Placing screws in the spine, a key step in spinal fusion and similar procedures, demands great precision. The surgeon must follow an exact trajectory through bone while controlling both the rotation of the screw and the rate at which it is pushed forward. If those two motions are not well matched to the screw’s thread, the screw can strip the bone, wander off the planned path, or sit poorly, all of which affect the strength of the repair and patient safety. Doing this consistently by hand, near sensitive nerves and the spinal cord, is difficult and leaves little margin for error.

What This Invention Does

The system pairs a robotic manipulator with a surgical tool that holds a screw of known thread geometry, and a robotic controller that stores that thread geometry in memory. The controller keeps the tool’s rotational axis aligned with a planned trajectory toward a target site on the spine. It then autonomously controls two things together: the rotational rate, how fast the screw spins, and the advancement rate, how fast the screw moves forward along the trajectory. Crucially, it coordinates these as a function of the screw’s known thread geometry, so that each turn of the screw advances it by the correct amount for its thread. This synchronised, thread-aware control helps the screw track its intended path and seat properly in the bone.

Key Features

• Thread-aware control. The controller drives the screw using its stored thread geometry.
• Coordinated motion. Rotational rate and advancement rate are controlled together rather than separately.
• Trajectory tracking. The tool’s axis is kept aligned with a planned path to the target site.
• Autonomous insertion. The robot manages the screw-driving motions rather than relying on manual feel.
• Robotic manipulator and tool. A robotic arm carries a tool configured to hold and rotate the screw.

Who Is Behind It

The applicant is MAKO Surgical Corp., a pioneer of robotic-arm assisted surgery now part of Stryker. The named inventors are Hyosig Kang, Jienan Ding, David Gene Bowling, Christopher W. Jones, Greg McEwan and Lucas Gsellman.

Why It Matters

Robotic assistance has spread quickly through orthopaedic and spine surgery because it can improve the accuracy and repeatability of difficult steps. A method that automatically matches a screw’s rotation to its advancement, based on the screw’s own thread, addresses one of the most error-prone parts of spinal instrumentation. Better screw placement can mean stronger fixation and lower risk near delicate structures. Protecting the system in Australia supports the company’s surgical robotics offering in the local market.

Related Concepts

• Robot-assisted surgery – the field this system belongs to.
• Spinal fusion – a common procedure that relies on accurate screw placement.
• Pedicle screw – the type of spinal hardware such systems place.
• Robotic arm – the manipulator that carries the surgical tool.
• Stryker – the medical technology company behind MAKO.

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AU 2026201916 was published in the Australian Official Journal of Patents on 2 April 2026 and is open for public inspection. Patent applications represent inventions that are sought to be protected and do not necessarily reflect commercially available products.