Coupler System Design for Surgical Navigation in Anterior Cruciate Ligament Reconstruction
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Date
2020-05
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The Ohio State University
Abstract
The anterior cruciate ligament is one of the main ligaments that act to keep the knee stable. ACL reconstruction (ACLR) is performed when the ACL is torn or ruptured, and it is one of the most commonly performed orthopedic surgeries with over a quarter million surgeries done each year in the US alone. The surgery consists of replacing the torn ACL with a tissue graft. The desired outcome for ACLR is to recreate a stable knee, and stability is currently analyzed subjectively before and after surgery with the Lachman and pivot-shift tests. Stability is analyzed to attempt to prevent suboptimal outcomes such as changes in range of motion and instability of the knee. Tools known as surgical navigation (NAV) systems are sometimes utilized in the operating room to track bony landmarks to get kinematic measurements. These systems consist of optical tracking cameras, marker arrays that are attached to the patient with coupler systems, and computer technology to track certain bones so that surgeons can perform surgical operations such as cutting and drilling more accurately. The more accurate operations can then potentially lead to better patient outcomes and a more stable knee. One reason NAV systems aren't widely used in ACLR is due to limitations in current coupler system designs. The main challenge with current coupler systems for ACLR is how to attach the markers to the tibia and femur in a secure fashion without making additional incisions to the patient. My project is to design a coupler system that is minimally invasive but still provides a secure attachment to enable the cameras to locate the bones in space accurately for ACLR. The design criteria include the device being able to produce accurate results, withstand the vibrations of surgery, and be minimally invasive. Different design concepts were hand sketched and then made in SolidWorks. In order to determine which design should be prototyped, a decision matrix was made and feedback from surgeons led to a chosen design. The chosen design consisted of a ball-and-socket joint and was fabricated with 3D printing. This design was chosen due to its ease of use and ability to fit majority of the design constraints. The device can be subjectively and quantitatively tested using an optical NAV system. The device can be analyzed on how well it fits the design criteria when using the coupler system on sawbones or cadavers. The device can be made out of aluminum in order to be sterilizable and lightweight. Overall, this research project has the potential to lead to a NAV system to be incorporated into ACLR that tracks the motion of the tibia and femur to better understand surgical techniques and how it correlates with patient outcomes. Ideally, changes can then be made in the operating room in order to recreate more stable knees.
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Keywords
Navigation system, ACL, Anterior Cruciate Ligament, Marker Array, Coupler System, Tracking