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Technical Brief

Device for Verifying the Patellar Cut During Knee Replacement Surgery

[+] Author and Article Information
Erica L. Rex

Biomedical Engineering,
University of Calgary,
5405 45 Street,
Taber, AB T1G 1G7, Canada
e-mail: rexe4@hotmail.com

Emmanuel M. Illical

Faculty of Medicine,
University of Calgary,
2500 University Drive Northwest,
Calgary, AB T2N 1N4, Canada
e-mail: eillical@gmail.com

Cinzia Gaudelli

Faculty of Medicine,
University of Calgary,
2500 University Drive Northwest,
Calgary, AB T2N 1N4, Canada
e-mail: cinzia.gaudelli@gmail.com

Barry Wylant

Faculty of Environmental Design,
University of Calgary,
2500 University Drive Northwest,
Calgary, AB T2N 1N4, Canada
e-mail: bwylant@ucalgary.ca

Karen C. T. Ho

Tangent Design Engineering,
480 Bracewood Crescent Southwest,
Calgary, AB T2W 3B8, Canada
e-mail: karen.c.t.ho@gmail.com

John G. Person

Box 13 Engineering,
415 Coventry Road Northeast,
Calgary, AB T3K 5N1, Canada
e-mail: john@box13eng.com

Carolyn Anglin

Department of Civil Engineering,
University of Calgary,
2500 University Drive Northwest,
Calgary, AB T2N 1N4, Canada
e-mail: carolyn.anglin@gmail.com

1Corressponding author.

Manuscript received August 1, 2015; final manuscript received February 17, 2016; published online May 12, 2016. Assoc. Editor: Rita M. Patterson.

J. Med. Devices 10(2), 024502 (May 12, 2016) (6 pages) Paper No: MED-15-1242; doi: 10.1115/1.4032870 History: Received August 01, 2015; Revised February 17, 2016

Cutting the kneecap (patella) in knee replacement surgery is challenging and can lead to pain and reduced function when done incorrectly. The presented device allows the surgeon to check the three-dimensional symmetry and thickness of the bone remnant before the operation is complete. Observations and measurements made on 36 resected artificial patellae and 16 resected cadaveric patellae matched well with computed tomography (CT) scans of the patellae with few exceptions; the exceptions should be addressable by changes in design and use. Average time to apply the device was 1 min.

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References

Figures

Grahic Jump Location
Fig. 1

(a) Anterior surface plate viewed from the top: the viewhole shows crosshairs underneath, marking the center of the patella; the arrow and “S” orient the device superiorly. (b) Anterior surface plate viewed from the bottom: the peg configuration, a 16 mm equilateral triangle, was developed based on extensive investigations, to represent the desired resection plane; the small screw allows the plate to rotate 180 deg to accommodate either a right or left patella and medial or lateral surgical approach.

Grahic Jump Location
Fig. 2

The dovetail sliding mechanism and set screw allow the device to be clamped onto the resected patella, and the thickness read from the marked scale. In this prototype device, only the thickness increments, not the thickness values were printed; the thickness value was determined as the difference from the known base value. For the clinical device, the thickness values will be provided.

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Fig. 4

TellaCal mounted on the cadaveric patella in the (a) everted position and (b) noneverted position. The marker array protruding from the device is used for the CAS version of the device; it was not used for the visual version of the device evaluated in this study.

Grahic Jump Location
Fig. 5

Custom-molded foam patellar models showing the two different geometries used in the artificial bone testing. The models were derived from CT scans of cadaveric specimens, on which four surgeons identified their desired resection planes.

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