Download Radial-capitellar implant

US 20060116771A1
(19) United States
(12) Patent Application Publication (10) Pub. No.: US 2006/0116771 A1
(43) Pub. Date:
Cooney, III et a].
(54)
RADIAL-CAPITELLAR IMPLANT
(76) Inventors: William P Cooney III, Rochester, MN
(US); Bernard F. Morrey, Rochester,
MN (US); David A. Leibel, Princeton,
MN (US)
Correspondence Address:
MORGAN, LEWIS & BOCKIUS LLP
1701 MARKET STREET
PHILADELPHIA, PA 19103-2921 (US)
Jun. 1, 2006
Publication Classi?cation
(51)
Int. Cl.
A61F 2/38
(52)
US. Cl.
(2006.01)
........................................................ .. 623/2011
(57)
ABSTRACT
A radial-capitellar implant for surgical replacement of the
capitellum of the humerus and, optionally, the head of the
radius. The radial-capitellar implant includes a capitellar
implant or surface replacement arthroplasty of the capitel
lum and a radial prosthesis for replacement of the head of the
(21) Appl. No.:
11/001,662
radius. In one embodiment the radial prosthesis includes an
articular head Which moveable articulates With a stem
(22) Filed:
Dec. 1, 2004
implantable in the radius.
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RADIAL-CAPITELLAR IMPLANT
[0007]
Resection of the radial head tends to cause persis
FIELD OF THE INVENTION
tent elboW instability folloWing elboW fracture, dislocation,
rotational instability injuries and medial lateral translation
[0001] The invention relates generally to the ?eld of joint
axial instability, particularly if the remaining stabiliZing
injuries. Excision of the radial head can also cause forearm
replacement prostheses for the human body. More speci?
cally, the invention relates to joint replacement prostheses
for the human elboW.
BACKGROUND OF THE INVENTION
[0002] The elboW is formed at the meeting of the distal
end of the humerus and the proximal ends of the radius and
ulna. In the elboW, the head of radius articulates With the
capitellum of the humerus and radial notch of the ulna. The
trochlear notch of the ulna articulates With the trochlea of the
humerus. When the forearm is in extreme ?exion, the head
of the radius ?ts into the radial fossa located just above the
capitellum. The lateral epicondyle is found on the lateral
structures have been compromised. Since the radial head
acts as a secondary stabiliZer to the elboW joint, once the
radial head is removed the soft tissue stabiliZers including
the collateral ligaments, the interosseous membrane and the
articular surfaces of the radial ulnar joints may be compro
mised and the instability of the joint tends to increase. Thus,
replacement of the radial head With an implant has been
embraced as a Way to attempt to restore anatomic normalcy
and functional usefulness to the elboW and forearm.
[0008] Radial head implants exist in the art. Typically,
radial head implants are available in multiple siZes to
approximate anthropomorphic differences in radial head siZe
in different patients. A radial head implant generally Will
aspect of the humerus just above the capitellum. The lateral
include a radial head component and a stem component. The
epicondyle serves as the insertion for one portion of the
radial head component is designed to anatomically articulate
With the convexity of the capitellum for an anatomic joint
supinator muscle Which attaches at about the proximal third
of the radius.
surface contact area. The circumference of the head matches
[0003] Along their lengths the radius and ulna are joined
the normal radioulnar joint articulation, preserves the annu
lar ligament and minimiZes release for exposure of impor
tant lateral ulnar collateral ligament. The radial head and
radial stem may be joined together by a Morse tapered
protrusion that is adapted to interface With a Morse tapered
by the interosseous ligament, also knoWn as the interosseous
membrane. The interosseous ligament has a ?brous structure
that is oriented on a bias relative to the axis of the forearm.
This ligamentous interconnection betWeen the radius and the
ulna serves to transfer loads at the Wrist from the radius to
the ulna. At the Wrist, the distal end of the radius is a larger
and more robust structure than the head of the ulna. Thus, at
the Wrist a large share of the load carried by the hand is
transferred to the radius. HoWever, at the elboW, the ulna is
substantially larger than the head of the radius. The
interosseous ligament serves to transfer loads from the
radius to the ulna so that the load is substantially equalized
at the elboW or so the load is carried more by the ulna than
the radius. The loading distribution betWeen the radius and
the ulna at the humeral articulation is dynamic, varying With
the position and motion of the forearm and hand.
[0004]
The radial head is an important component of
normal elboW and forearm function. The radial head con
tributes to both the radiocapitellar and proximal radioulnar
joints.
[0005] The radial head makes a 12 to 15 degree lateral
angle to the radial shaft. This lateral angle is aWay from the
radial tuberosity Which is located distal to the radial head on
the medial side of the radius. Various ligaments about the
radial head provide important soft tissue support and are
essential to elboW stability. The stress distribution at the
cavity. Generally, the Morse tapered cavity is located in the
head Which alloWs placement of the radial head onto the
protrusion on the radial stem.
[0009] A typical radial prosthesis has a stem con?gured
for implantation into the intramedullary canal of the proxi
mal radius. Some types of radial head implant include a
limited ball joint articulation betWeen the radial head com
ponent and the stem component. These are sometimes
knoWn as bipolar implants. In this type of implant, the
concave articular surface of the radial head anatomically
articulates With the convexity of the capitellum While the
radial head articulates With the stem of the implant. This
alloWs the use of a radial head implant in situations Where
the radial head may be damaged in such a Way as to make
implantation of a ?xed radial head implant dif?cult or
impossible. Use of a bipolar radial head implant alloWs for
some adjustment of the head of the implant With the capi
tellum once the implant is in place. The articulation betWeen
the head and the stem alloWs for the correction of angular
alignment deformities betWeen the radius and the capitel
lum. The ball and socket design of this type of radial head
implant alloWs radial-capitellar contact to be maintained
through a functional range of ?exion and forearm rotation.
elboW varies in pronation and supination but averages about
60 percent to the radiohumeral joint and about 40 percent at
[0010]
the ulnar humeral articulation.
hand Will also damage the capitellum of the humerus. In
addition, the capitellum is sometimes to subject to arthritic
[0006]
The radial head can be damaged in many Ways.
Unfortunately, some falls onto an outstretched
degeneration or increased Wear after placement of a radial
One common source of damage the head of the radius is a
fall onto an outstretched hand. Historically, if the radial head
head implant.
Was damaged so severely as to be impossible to repair With
head resection tends to cause signi?cant adverse effects on
[0011] As discussed above, sometimes resection of the
radial head is performed Without an implant. Resection of
the radial head leaves the patient With a so-called ulna plus
variation Which tends to lead to Wrist pain Which, in turn, can
be debilitating. For these reasons, it Would be bene?cial to
the patient to be able to surgically replace and restore the
elboW and forearm function.
capitellum as Well as the radial head.
the use of bone screWs or other internal ?xation structures,
the radial head Was resected and the elboW closed. Radial
head resection Was sometimes necessary due to fracture,
osteochondrosis or secondary arthritis. Unfortunately, radial
Jun. 1, 2006
US 2006/0116771A1
[0012] Traumatic injury of the radioulnar joint is common.
Injuries to the radioulnar joint include radial head fractures
and radial head fractures associated With ligament injuries;
prosthesis for implantation to replace the natural head of the
radius Where it articulates With the capitellum and the ulna.
In one embodiment of the invention, the radial head implant
combined proximal ulna fracture With radial dislocation or
fracture; radial head fracture associated With dislocation of
includes a stem and a head.
the elboW; and forearm and elboW injuries in combination.
Forearm and elboW injuries include radial head fracture
combined With interosseous membrane disruption, the so
called Essex-Lopresti lesion. In the case of an Essex
Lopresti lesion or interosseous ligament tear, the transfer of
loads from the hand and then from the radius to the ulna is
compromised. This lack of transfer from the radius to the
ulna creates an increased load at the radial head Where it
meets the capitellum Which increases Wear on the capitellum
as Well as the radial head.
[0013] Thus, it Would be bene?cial to the orthopedic arts
to have an implant available to surgically repair damage to
the capitellum as Well as to the head of the radius.
[0019] The head of the radial head implant de?nes a
concave articular surface that may be formed of ultra high
molecular Weight polyethylene (UHMWPE) or another
durable self-lubricating material. The head further includes
a stem interface portion Which de?nes a substantially cylin
drical cavity into Which a portion of the stem inserts. The
cavity may be formed With a morse tapered ?t to alloW ease
of placement of the head onto the stem. The portion of the
stem of the radial head implant that is inserted into the
intramedullary canal in this embodiment has a smooth
continuous surface and a bend forming an angle Which
occurs about midWay doWn the length of the stem. The stem
further includes a collar Which abuts the head of the radial
head implant along With the morse tapered extension to form
the interface betWeen the head and the stem.
SUMMARY OF THE INVENTION
[0020] In another embodiment, the radial head implant
The present invention solves many of the above
includes a head and a stem that are joined by a ball and
mentioned problems by making available a radial-capitellar
implant including a capitellar implant to be implanted into
deformities of up to about ten degrees. In this embodiment,
[0014]
the distal end of the humerus. The invention may also
include a capitellar implant to replace the capitellum of the
humerus in combination With a radial head implant to
replace the head of the radius and to articulate With the
capitellar implant. Another aspect of the invention includes
a capitellar implant and a bipolar radial head implant in
socket joint to alloW for correction of angular alignment
the radial head implant includes a head With a concave
articular surface that is lined With ultra high molecular
Weight polyethylene or another durable self-lubricating
material, an intermediate portion and a secondary articular
portion Which articulates With the stem. The intermediate
portion is typically formed of cobalt chromium stainless
steel, titanium or another biocompatible metal. The second
Which the head of the radial head implant includes an
articulated head that can conically, rotationally, articulate
relative to the stem of the radial prosthesis to replace the
head of the radius.
With the radial prosthesis stem.
[0015] The capitellar implant of the present invention
[0021] Altemately, the articular portion and the interme
ary articular portion includes a female ball and socket
interface and a male ball and socket interface to interface
about one hundred thirty ?ve to one hundred forty degrees.
The capitellar implant further includes a ?at on its medial
diate portion can be formed as a single piece formed from
UHMWPE or another durable self lubricating material. In
this situation, the head of the radial prosthesis includes a
female ball and socket interface and a male ball and socket
interface to interface With the radial prosthesis stem as Well
side and a curved ?at on its lateral side. The curved ?at on
the lateral surface alloWs for excursion of the radial nerve
implant.
generally includes a body and a stem. The body of the
capitellar implant de?nes a convex articular face. The con
vex articular face may have a spherical surface and extends
as a concave articular face to articulate With the capitellar
over the lateral surface of the implant. The curved ?at also
[0022]
facilitates the smooth gliding of the joint capsule and
ligamentous structures over the implant during ?exion/
a collar similar to that described above as Well as a sphe
The stem of this embodiment includes a stem With
head of the radius over an arc of approximately one hundred
roidal ball protruding from the stem and extending from the
collar in a direction opposite the stem. The spheroidal
protrusion rests in a spheroidal female cavity. The female
cavity accepts the male portion of the ball joint of the head
thirty ?ve to one hundred for‘ty degrees to alloW full range
of motion in ?exion and extension of the forearm.
ball and socket portion of the head of the radial head
extension and pronosupinatory motions. The convex articu
lar face alloWs articulation of the capitellar implant With the
[0016] The stem of the capitellar implant is offset approxi
mately 10 degrees to the medial side. The stem may be
substantially square in cross section and tapered to a sub
stantially square end. The stem of the capitellar implant may
be treated to encourage osseointegration such as by appli
cation of titanium plasma coating.
portion and the spheroidal protrusion inserts into the female
implant. This structure increases the contact area betWeen
the articular head and the articular stem improving the Wear
characteristics and distributing loading over a larger area. In
this embodiment of the invention the stem may also be
treated to encourage osseointegration such as by application
of a commercially pure titanium plasma coating.
[0017] The side of the capitellar implant from Which the
BRIEF DESCRIPTION OF THE DRAWINGS
stem extends includes a bone interface surface Which may
have tWo ?at facets. The ?at facets are angled relative to one
0023 FIG. 1 is a P lan vieW of the radial-caP itellar
implant in accordance With the present invention in a ?exed
another at an angle of approximately 135 degrees.
position;
[0018]
In another embodiment, the invention includes
both the capitellar implant as described above and a radial
0024
FIG. 2 is a P lan vieW of the radial-caP itellar
implant in a partially extended position;