Knee Alignment Verification System Utilizing Visual

Recognition Technology and Imaging

Senior Design ProjectMegan Luh

Hao LuoMarch 23 2010

Total Knee Arthroplasty (TKA)One of the most common

orthopedic procedures performed

Surgeon removes damaged bone surfaces using implant specific jigs

Attaches implants that mimic shape of the natural knee

90% successful but 10% are misaligned

Cause pain and will require another surgery

Solutions to the alignment problemPraxim Computer

guidance systemThree trackers attached

to infrared camerasPlaced on pelvis, femur,

and tibiaAccuracy of system

depends on surgeon placement of trackers

CostlyRequires set up and take

down time

AnalysisProblem Statement

Current methods of limb alignment are costly and time consuming

Dependent on individual surgeon skill for accurate calibration

Performance CriteriaConstrained by surgical

space, time, and resources

Limited by lens quality, camera resolution and frame rate, and noise level

Primary ObjectiveProof of Concept that

visual recognition software can be applied to the field of limb alignment in real-time for surgical procedures

Improve the method of limb alignment used during surgical procedures

Create a new method that is more efficient, can be used in real-time, more economically profitable for hospitals.

FactorsParameters

Quality is determined by the speed, accuracy, and precision of the computer algorithm

Overall operating costs are reduced with a faster system

Patient and surgeon both benefit from a faster, more accurate system

Average operating room costs = $1000.00 per min

Surgical costsDoctor visits; pre

surgery and exams (total 3) $512

MRI $992.00 Hospital $4,909 Anesthesia 718.20 Doctor Charge: $3591

(surgery) total amounts

=10,722.20 

MarkerDesigning a cross shape

marker with some spheres on it to mark the x-ray

Use a biocompatible, disposable plastic with an x-ray contrast medium: polyethylene, polycarbonate

It consists of four spheres connected in a cross configuration

The two pairs of spheres vary in size and in color

Reason for the designPair of spheres

detectionCross configuration

Perspective Different length

Work completedMarker detectionMarker trackingLength detection

Work to be doneAngle calculation3D Marker

fabricationExport data

ConclusionThe goal of this project is to accomplish a

proof of concept that visual recognition software can be applied to the field of orthopedic limb alignment in a real-time surgical procedure.

So far, we have solidified the goal and mapped out the details of software implementation.

Futures works include creating the software, troubleshooting, and testing the result.

ReferencesDuda, R. O. and P. E. Hart, "Use of the Hough

Transformation to Detect Lines and Curves in Pictures," Comm. ACM, Vol. 15, pp. 11–15 (January, 1972).

Bradski, Gary, and Adrian Kaehler. "Image Transforms, Contours, Project and 3D vision." In Learning OpenCV: Computer Vision with the OpenCV Library. 1st ed. Sebastopol: O'Reilly Media, Inc., 2008. 109-141, 144-190, 222-251, 370-458.

Chleborad, Aaron. "OpenCV's cvReprojectImageTo3D." Graduate Student Robotics Blog. http://people.cis.ksu.edu/~aaron123/?m=20090629 (accessed December 18, 2009).