BACKGROUND OF THE INVENTION

The present application is directed to systems and methods for surgical rod bending. More particularly, the present invention relates to a system and method for controlling a surgical rod bending system to effectuate improved creation of surgical rods.

Surgical rods are used with bone screws in spine surgery to add stability to and/or correct curvatures of the spine. Surgical rods often have to be contoured to fit a desired curve of the spine and to intersect with sometimes irregular locations of bone screw heads.

Currently, the most common method for imparting complex bends to surgical rods is entirely manual. A surgeon must first determine the desired curvature of the rod by temporarily positioning a flexible surrogate rod in the bone screw heads and bending the surrogate rod by hand until it fits properly in each bone screw head. The surgeon must then remove the surrogate from the surgical table and take the surrogate to a side table where it is used as a visual guide to bend an actual surgical rod with a manual rod-bending tool. This procedure is subjective and can lead to metal fatigue if the surgical rod is accidentally over-bent and then re-bent in the opposite direction. In addition, this method can often subject the surgical rod to an increased risk of surface damage caused by accidental contact with sharp metal tools, resulting in local stress riser points and potential rod breakage after implantation. This method is also time-consuming, especially for inexperienced surgeons.

Attempted solutions to the above manual methods involve automated mapping and bending of surgical rods. For example, some newer systems include an input device that receives or calculates virtual coordinates of a surgical rod with a desired curvature, and a motorized rod-bending device that bends a surgical rod according to the coordinates. More specifically, the coordinates are used to produce bend commands for controlling linear and rotational movement of a straight surgical rod as it is fed through the motorized rod-bending device. The bend commands are also used to control a force-actuating mechanism which bends the surgical rod around a post as it is fed through the motorized rod-bending device.

Common force-actuating mechanisms include bending arms which impose a radial or rotating force on the surgical rod so that the surgical rod bends around the post. These force-actuating mechanisms tend to be bulky and require substantially large systems for applying enough force to bend the surgical rods. In addition, some force-actuating mechanisms fail to provide enough support for the surgical rod to ensure that bending only occurs at the desired points. Other force-actuating mechanisms provide such support but, as a result, impose additional limitations such as restricting the degree of rotation of the surgical rod as it is fed through the rod-bending device. These restrictions limit the range of bending capabilities of the rod-bending device and therefore only permit certain combinations of rotation and bending.

Therefore, it would be desirable to provide a compact system to automatically bend a surgical rod to a desired curvature. Furthermore, it would be desirable to have such system sufficiently support the surgical rod without restricting its range of bending capabilities. Further still, it would be desirable to have methods and apparatuses for creating, detecting, and finalizing a desired curvature of a surgical rod using an automatic rod bending system.

SUMMARY OF THE INVENTION

The present invention overcomes the aforementioned drawbacks by providing an automated surgical rod bending system that permits full rotation of a surgical rod as it passes through the system, independent of previous bends performed along the length of the surgical rod. The present invention additionally incorporates methods for detecting a desired curvature of a surgical rod and outputting such detection information to the automated surgical rod bending system. Further still, the present invention provides methods for controlling an automatic rod bending system.

In accordance with one aspect of the invention, a method is disclosed for bending a rod configured to be implanted into a patient. The method includes determining a shape for the rod to be formed into to allow a rod to be implanted into a patient, determining a plurality of pedicle points along the rod where pedicle screws will attach the rod to the patient when the rod is in the shape, and determining a plurality of intermediate points along the rod and between the plurality of pedicle points. The method also includes identifying a plurality of line segments defined by adjacent ones of at least one of the plurality of pedicle points and the plurality of intermediate points and determining an angle measurement to be formed between at least two adjacent ones of the plurality of line segments to form the rod into the shape. The method further includes determining bending parameters to perform on the rod to form the angle measurement between the at least two adjacent ones of the plurality of line segments and feeding the rod into a bending system configured to bend the rod into the shape using at least one of the bending parameters and the angle measurement.

In accordance with another aspect of the invention, a system is disclosed for bending a rod into a shape designed for implantation into a patient. The system includes a plurality of guide rollers, a linear movement device configured to axially feed the rod in a first direction between the plurality of guide rollers, and a rotational movement device configured to rotate the rod as it is axially fed between the plurality of guide rollers. The system also includes a bending device configured to impose bending forces against the rod in a second direction perpendicular to the first direction after it is fed between the plurality of rollers. The bending device is positioned adjacent to the plurality of guide rollers so that the imposed bending forces against the rod causes the rod to bend along a curve of one of the plurality of guide rollers. The system further includes a controller configured to receive an indication of a plurality of line segments defined on the rod and an indication of an angle measurement to be formed between at least two adjacent ones of the plurality of line segments. The controller is further configured to identify bending parameters to perform on the rod to form the angle measurement between the at least two adjacent ones of the plurality of line segments and control operation of at least the bending device using the bending parameters to create an angle having the angle measurement between the at least two adjacent ones of the plurality of line segments.

In accordance with another aspect of the invention, a system is disclosed for bending a rod into a shape designed for implantation into a patient. The system includes a base including a base passage extending there through, a linear movement device configured to axially feed the rod in a first direction through the base passage, and a rotational movement device coupled to one of the base and the linear movement device, the rotational movement device configured to rotate the rod while being fed through the base passage by the linear movement device. The system also includes a bending device moveable in a second direction perpendicular to the first direction to impose bending forces against the rod and a controller. The controller is configured to receive an indication of a plurality of line segments defined on the rod and an indication of an angle measurement to be formed between at least two adjacent ones of the plurality of line segments. The controller is also configured to identify bending parameters to perform on the rod to form the angle measurement between the at least two adjacent ones of the plurality of line segments and control operation of at least the bending device using the bending parameters to create an angle having the angle measurement between the at least two adjacent ones of the plurality of line segments.

The foregoing and other aspects and advantages of the invention will appear from the following description. In the description, reference is made to the accompanying drawings which form a part hereof, and in which there is shown by way of illustration a preferred embodiment of the invention. Such embodiment does not necessarily represent the full scope of the invention, however, and reference is made therefore to the claims and herein for interpreting the scope of the invention.

