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ASTM Selected Technical Papers
Modularity of Orthopedic Implants
By
DE Marlowe
DE Marlowe
1
Symposium chairman and co-editor
;
FDA, Center for Devices and Radiological Health
?
Rockville, MD 20850
.
Search for other works by this author on:
JE Parr
JE Parr
2
Symposium chairman and co-editor
;
FDA, Center for Devices and Radiological Health
?
Rockville, MD 20850
.
Search for other works by this author on:
MB Mayor
MB Mayor
3
Symposium co-chairman and co-editor
;
Dartmouth Hitchcock Medical Center
?
Lebanon, NH 03756
.
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ISBN-10:
0-8031-2415-5
ISBN:
978-0-8031-2415-8
No. of Pages:
248
Publisher:
ASTM International
Publication date:
1997

Today in the United States, 95% of all total hip implants contain at least one modular junction. The most common of these junctions connects the femoral head and neck taper. Because this connection utilizes a Morse taper, various materials and design variables can influence fretting and corrosion behavior at the mating surfaces, and ultimately the longevity of the device.

In order to isolate and study the behavior of the femoral head/neck taper connection, a simplified model of a neck taper was designed. Test specimens were manufactured of Ti-6Al-4V and Co-Cr, and were designed to accept a Co-Cr femoral head. These constructs provided control in the experiment by focusing on the femoral head/neck taper interface, and by facilitating debris collection. Each construct was encapsulated with Ringer's solution and subjected to a fatigue load of 490 N to 4900 N at a rate of 10 hertz for ten million cycles. Using direct current plasma-optical emission spectroscopy (DCP-OES), the Ringer's solution was analyzed for titanium and cobalt ions after the fatigue test. The titanium level measured for the Ti-6Al-4V/Co-Cr constructs was less than 0.05 mg/L. For the Ti-6Al-4V/Co-Cr and Co-Cr/Co-Cr constructs, the cobalt levels were 0.95 – 0.23 mg/L and 1.16 – 0.57 mg/L, respectively.

This test method was designed to determine the debris generated at the femoral head/neck taper interface by controlling for specific design/fixation variables. It can be used to predict how such factors as material, taper diameter, taper angle, taper engagement, and tolerances affect the generation of wear debris during fatigue. Although the results do not predict the debris generation of an actual hip prosthesis, they may indicate performance characteristics which can be generalized to in-vivo behavior of the device.

1.
Gilbert
,
J.L.
, “
Degradation in Modular Femoral Hip Prosthesis Tapers
.” NIH Consensus Development Conference on Total Hip Replacement,
1994
, pp. 49–53.
2.
Collier
,
J.P.
;
Surprenant
,
V.A.
;
Jenson
,
R.E.
; and
Mayor
,
M.D.
, “
Corrosion at the Interface of Cobalt-Alloy Heads on Titanium-Alloy Stems
.”
Clinical Orthopaedic Related Research
,
271
,
1991
, pp. 305–312.
3.
Bauer
,
T.W.
,
Brown
,
S.A.
,
Jiang
,
M.
,
Panigutti
,
M.A.
, and
Flemming
,
C.A.C.
, “
Corrosion in Modular Hip Stems
.” Transactions of the 38th Annual ORS,
02
1992
, p. 354.
4.
McKellop
,
H.A.
,
Sarmiento
,
A.
,
Brien
,
W.
, and
Park
,
S.H.
, “
Interface Corrosion of a Modular Head Total Hip Prosthesis
.”
Journal of Arthroplasty
,
7
(
3
)
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, pp. 291–294.
5.
Dujovne
,
A.R.
,
Bobyn
,
J.D.
,
Krygier
,
J.J.
,
Wilson
,
D.R.
, and
Brooks
,
C.E.
, “
Fretting at the Head/Neck Taper of Modular Hip Prosthesis
.” Transactions of the 4th World Biomaterials Congress,
Berlin, Germany
,
04
1992
, p. 264.
6.
Lieberman
,
J.R.
,
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,
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,
Garvin
,
K.L.
,
Klien
,
R.W.
, and
Salvati
,
E.A.
, “
An Analysis of the Head-Neck Taper Interface in Retrieved Hip Prosthesis
.”
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,
300
,
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, pp. 162–167.
7.
International Standard ISO 7206-3 Part 3,
Determination of the endurance properties of stemmed femoral components without the application of torsion
. (
15
06
1988
).
8.
Rohrle
,
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,
Scholten
,
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,
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,
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,
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,
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, and
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,
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, “
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.”
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,
17
(
6
),
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, pp. 409–424.
9.
Hardt
,
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, “
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.”
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,
100
(
2
),
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, pp. 72–78.
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