Standardizing Metrics and Methods for Weight Bearing 3D Imaging Devices in Orthopedic Applications

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Development of Weight Bearing dynamic 3D imaging techniques and standards for orthopedic applications

Currently radiologists and orthopedic doctors rely on non-weight bearing imaging techniques to diagnose biomechanical conditions associated with the various weight bearing joints such as the hips knees and ankles. In most cases the current techniques are not able to reveal the cause creating the orthopedic condition and therefore both diagnosis and treatments are mostly based on assumptions and qualitative approaches. For example a person with a given foot deformity (e.g. a collapsed arch) as revealed by a 2D radiographic image may be prescribed a custom built orthotic or a brace to correct the deformity. However other than a visual qualitative inspection, doctors have no tools to evaluate if the correction made by the orthotic in this case is adequate or not for mitigating the foot condition. At best, the current system relies on a trial and error approach that in most cases do not resolve the condition at hand.

Current imaging tools include anything from standard two dimensional (2D) radiographic images using x-rays up to non-weight bearing 3D MRI or CT static images. None of these techniques however are able to reveal in real time the loading effect that the body has on the joints of the lower body. In the recent years a number of static weight bearing 3D imaging technologies have made their way into the market place which include: 3D standing CT imaging units as well as 3D standing MRI units. These latest devices allow to image the lower body parts in a standing position. In this way the effect of the body load on the ankle joint, knee joint and hip joint can be observed. Although these techniques are becoming available, they are not being used by podiatrists and orthopedic doctors for the evaluation in real time of orthotics and braces due to a lack of standard metrics available for this purpose from the manufacturer of these devices.

There is also the need to extend these efforts to being able to image in real time dynamically a patient while walking on a treadmill to be able to capture the entire biomechanical function of the joints. In this way one can for example observe if under motion certain joints are compromised during several gait cycles as opposed to what is revealed in a single time event captured by a static 3D image.

The current need aims to review current technologies to develop a weight bearing dynamic 3D imaging technique. Some efforts have been initiated in this direction using fluoroscopy and MRI but they are still in its infancy.

The need for developing 3D imaging tools for evaluating orthotics. How can we improve the current practice? Summary of discussions.

One of the goals during this session was to get input form audience participants on the need for developing a 3D real-time imaging tool for evaluating orthotics inside shoes with the patient in a weight bearing configuration (standing). So once the orthotic has been made (by a professional that delivers the orthotic to the patient) a 3D image of the patient can be taken in the weight-bearing position, with the patient standing in his/her shoes with the new orthotic installed in the shoe. This type of analysis could be used to evaluate if the orthotic does what it is meant to do. The 3D weight bearing images can provide information such as specify bone alignment issues using the new orthotics, if the new orthotic is providing the expected amount of correction without compromising other foot anatomical issues, if the spacing between the major foot joints are affected by the new orthotic/ shoe combination, etc… This type of information can provide real-time feedback to the professional to do an immediate adjustment to the orthotic or decide to use a different shoe with this newly made orthotic.

This type of assessment cannot be done visually as it is currently done by watching the patient walk with the new orthotics inside the shoe. The current approach is based on a rough guess and simplistic approach by observing if the patient supinates or pronates or if she/ he looks “roughly” neutral with the new orthotic. This misses a lot of information regarding the foot biomechanics which can only be addressed with a 3D imaging technique that allows visualizing the bones and joints in the feet. Implementing the use of a 3D imaging tool to evaluate an orthotic that has been custom made, could prevent sending patients home to “try the orthotic out” as it is currently done in most cases risking further issues developing as a result of missing the effects that the new orthotic are causing to the foot. This same concept can be extended to the use of braces.

Professionals that may be interested in this are those that are making and providing orthotics to patients, for example, orthopedic doctors, podiatrists, pedorthists, and selected physical therapists that focus on making orthotics to address misalignment issues. Another potential application that was discussed is the need for using such type of imaging tools to monitor a foot alignment issue over the years for a given patient by determining effective and adequate markers or metrics from and/or for these images.

The afternoon session on Tuesday March 28, 2017 included the following presentations on this topic. Below are the titles and names of the speakers. The presentations can be found on the CIRMS website.

1:45 PM-2:00 PM, Introduction to the session: The need for developing 3D imaging tools for evaluating orthotics. How can we improve the current practice? Ronnie Minniti, Ph.D., NIST

2:00 PM-2:30 PM,

Low dose, mini C-arm fluoroscopy for hand and foot applications

Kevin Wilson, Ph.D., Hologic

2:30 PM -3:00 PM, Why Cone Beam CT can make 3D the Standard of Care in Extremity Imaging.

Stuti Singh, Ph.D., Curvebeam

3:00 PM - 3:15 PM, EQINA, A quick overview of a weight bearing 3D imaging system.

Regina Fulkerson, Ph. D., RKF Consultants