X-Ray Assistive Device for Standardizing the Knee Templating Process

Knee templating is used as part of the pre-operative planning for knee replacement to determine the best fit for an implant. The current assistive devices used to determine fit are unreliable and inaccurate for proper patient fit. A new device is suggested to overcome these limitations.

The Need

Over 600,000 knee replacements are performed per year. As part of the pre-operative planning for surgery, x-ray images are taken to determine the proper fit for the implant. Even with the use of a calibration ball, this knee templating procedure remains inaccurate and unreliable for a number of reasons. Improper placement of the calibration ball and any slight change in the patient’s leg position changes the angles of the features used in pre-operative planning. These errors can result in a longer surgery, improper implant fit, and increased costs to the patient, insurance provider, and hospital.

The Technology

This technology is a device to keep a patient’s leg in a consistent position while being imaged as part of the X-ray templating process for knee implants. Many of the features that are incorporated into this design are important and useful in improving the consistency of the angles at which the knee and foot are situated in each X-ray image. Two key features that perform this task are the backboard of the device that has a preset angle for the knee joint of 20 degrees, as well as the foothold that has the ability to maneuver 45 degrees in either direction. The device also includes the ability of the device to extend and retract to fit different heights of patients and to incorporate multiple calibration balls.

Commercial Applications

Knee replacement surgeries are one of the most common joint replacement surgeries performed each year. This device greatly serves the orthopedics field and may have similar utility in replated join replacement applications with some design modifications.


The proposed technology overcomes existing assistive devices currently utilized in pre-operative planning for knee replacements by creating a standardized method for stabilizing patients of various sizes, optimal placement of the calibration ball, patient position, and angle of the radiographic image taken.

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