OTA 2006 Posters
Scientific Poster #70 Basic Science
The Anatomic Periarticular Plate: An Oxymoron
Kanu Goyal, BS (*); Anthony F. Skalak, MD (*);
Yohannes Haile-Selassie, PhD (*); Randall E. Marcus, MD (*);
Heather Vallier, MD (*); Daniel R. Cooperman, MD (*);
Cleveland Museum of Natural History, MetroHealth Medical Center, University
Hospitals of Cleveland, Cleveland, Ohio, USA
Purpose: Our objective was to develop a method to quantify plate
fit and to test the method.
Methods: Normal tibias from 25 black males, 27 white males, 26 black
females, and 25 white females were obtained. Medial and lateral, 8-hole,
3.5-mm, anatomic, proximal, periarticular plates (Zimmer Corp, Warsaw, Indiana)
were fixed to the tibias. Using a Microscribe G2LX digitizer, Rhinoceros,
Excel, and Matlab software, we analyzed (1) the angular relationships between
the tibia and the plate as well as (2) the volume of space between the tibia
and the plate.
Results: Tibial length ranged from 29 cm to 46 cm. Medial and lateral
tibial plateau slopes averaged 81° (range, 69-92°). Plateau-plate
angles ranged from parallel to 13°, while shaft-plate angles ranged
from parallel to 10°. The volume of space under the plates was analyzed
in three sections - Proximal (under the head of the plate, which is parallel
to the tibial plateau), Middle (under the three proximal shaft holes), and
Distal (under the five distal shaft holes).
The volume of space between the tibias and the plates was:
|
Proximal |
Middle |
Distal |
| Medial |
619 mm (±215 mm) |
471 mm (±160 mm) |
794 mm (±669 mm) |
| Lateral |
643 mm (±183 mm) |
722 mm (±263 mm) |
386 mm (±285 mm) |
If the space under the plate was evenly distributed (<300 mm difference
between the Middle volume and the Distal volume) the fit was defined as
Even. Plates that failed to make good contact with the Middle portion
of the tibias (Middle volume - Distal volume = >300 mm) were defined
as Spanning. If premature plate-tibia contact elevated the distal
end of the plate (Distal volume Middle volume = >300 mm), the plates
were defined as being in Impingement.
|
Spanning |
Even |
Impingement |
| Medial Plate |
33 |
26 |
44 |
| Lateral Plate |
78 |
17 |
8 |
The head of the plate was aligned within 2° of parallel with the
tibial plateau in 57% of specimens on the medial side and 45% on the lateral
side. The shaft of the plate was aligned within 2° of parallel with
the shaft of the tibia in 34% of specimens on the medial side and 79% on
the lateral side.
Conclusions/Significance: We developed a digital method for representing
plate fit. We defined an anatomic fit as one that has <2,000 mm of space
between the plate and the tibia, an Even fit, and the plate aligned
within 2° of parallel with the tibial plateau and the tibial shaft.
This type of fit appeared "anatomic" to the eye. This fit occurred
10 times on the medial side and 10 times on the lateral side of 103 normal
tibias. We believe that the term "anatomic" should be clearly
defined with data and that plate contours should be clearly described with
data.
If noted, the author indicates something of value received.
The codes are identified as a-research or institutional support; b-miscellaneous
funding; c-royalties; d-stock options; e-consultant or employee; n-no conflicts
disclosed, and *disclosure not available at time of printing.
·
The FDA has not cleared this drug and/or medical device for the use
described in this presentation (i.e., the drug or medical device is being
discussed for an "off label" use). · · FDA
information not available at time of printing.