Mandibular prosthesis apparatus for mounting on the remaining stump portion of the ascending ramus, at the posterior end of a human mandible, from which has been removed by surgical intervention a diseased or fractured condylar process portion of the ramus as part of the temporomandibular (TM) joint complex of the mandible. The prosthesis apparatus consists of: a synthetic condylar replacement member which is formed of non-toxic, biocompatible Delrin acetal resin and includes an upper knob-shaped condyle portion and a lower cylindrical condyle-supporting stem portion; and a ramus attachment fixture which includes a cylindrical sleeve portion for receiving the cylindrical condyle-supporting stem portion of the condylar replacement member and a mounting panel for attaching the fixture to the stump portion of the ramus. The ramus attachment fixture is formed of tissue-biocompatible, perforated titanium sheet material. Bone screws, applied through the perforations of the titanium sheet material, affix the ramus attachment fixture, via its mounting panel, to the ramus stump and secure the stem portion of the synthetic condylar replacement member within the cylindrical sleeve portion of the attachment fixture to maintain proper orientation of the knob-shaped condyle portion of the replacement member within the TM joint complex of the mandible.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The Present invention relates to the field of human mandibular prostheses. 
More particularly, the invention relates to improved prosthetic apparatus 
for the repair and/or replacement of the condylar process of the human 
mandible. 
2. Description of the Prior Art 
The human mandible is a U-shaped bone (lower jaw bone) having a generally 
horizontal body portion with an anterior prominence (mandibular symphysis) 
defining the chin in the facial structure. A posterior branch or ramus 
extends upwardly and rearwardly from each end of the body portion. The 
upper end of each ramus terminates in a forward coronoid process and a 
rearward condyloid process or condyle. The condyle is a knob-shaped 
prominence which fits into a cup-shaped socket known as the glencid fossa 
formed in the temporal bone of the skull. The condyle, glenoid fossa, and 
supporting muscle tissue on each side of the skull define a 
temporomandibular joint (TMJ) which permits the lower jaw to be freely 
movable. 
Surgery in the area of the TM joints of the human mandible frequently 
involves the necessity of total replacement of the condyle head or entire 
condylar process of the right or left side or both sides of the mandible. 
Such surgeries may involve arthroplasty for advanced degenerative TM joint 
disease, repair and reconstruction of ankylosed TM joints, repair of 
traumatic fractures of the condyle resulting in loss of normal condylar 
structure and function, and surgical treatment of congenital hypoplasia of 
the ramus and condylar process. 
A number of types of metallic alloplastic materials have been utilized in 
the past for mandibular condylar replacements including chrome-cobalt 
alloys, pure titanium and titanium alloys and stainless steel. In 
addition, Proplast, Teflon, Silastic, and other synthetic alloplastic 
materials have been utilized in an effort to obtain maximal function, 
anatomic reproduction and long life of TM joint replacement protheses. 
Clinical reports have indicated that metallic condyle replacement 
prostheses have produced bone loss and erosion of the interfacing surface 
of the cup-shaped glenoid fossa. Other adverse clinical reports have 
resulted where Proplast, Teflon and Silastic synthetic materials have been 
used to form condyle replacement prostheses and such materials have been 
rejected by the TMJ environment frequently resulting in irreparable harm 
and damage to the TM joint complex. 
In U.S. Pat. No. 3,720,959, granted in 1973 to G. W. Hahn, there is 
disclosed mandibular prosthetic appliances constructed of malleable metal 
mesh material, particularly stainless steel mesh fabricated by casting. 
Where the Hahn mandibular prostheses involve replacement of the condyle 
such component is fabricated of an acrylic resin material and formed 
about, and secured to, a metallic mesh body member affixed to the ramus or 
ramus stump. Over the years the Hahn mandibular prostheses for condyle 
replacement have been found to be expensive to manufacture and difficult 
to install and adjust to proper TMJ alignment. Most importantly, such 
prostheses have experienced unfavorable short-term and long-term 
biocompatibility and wear resistance of the materials of construction in 
and under the TMJ environment. 
In 1988, T. A. Collins was granted U.S. Pat. No. 4,726,808 disclosing 
mandibular prostheses comprised of pairs of spaced (substantially 
parallel) metal strips which are joined together at one end and are placed 
on opposite sides of mandibular bone stumps that may remain on one side of 
damaged areas of the mandible. The opposing metal strips are each provided 
with alternating threaded and non-threaded holes. The non-threaded holes 
of one strip are oriented so as to oppose the threaded holes of the other 
strip so that screws can be extended between the strips (through drilled 
holes of the intermediate mandibular bone) from a non-threaded hole of one 
strip to a threaded hole of the opposing strip. In one disclosed form, the 
Collins mandibular prosthesis includes, at the joined end of a set of the 
parallel metal mounting strips, an attached metallic artificial condyle. A 
sleeve of silicone or other suitable plastic material is applied over the 
condyle. It has been well established that Collins-type condyle 
replacement protheses: are difficult to install because screw hole 
alignment is not maintained when contouring of the strips is required, 
provide no means for adjusting the orientation of the condyle head to 
match the cup-shape of the glenoid fossa, and include condyle head 
materials that are objectionable in the TMJ environment. 
It is an important object of the present invention to provide a mandibular 
prosthesis for repair and replacement of the condylar process of the human 
mandible that can be surgically implanted more quickly, easily and safely 
than the prostheses that are presently available. 
It is another important object of the invention to provide a mandibular 
prosthesis for repair and replacement of the condylar process of the TMJ 
complex that is constructed of biocompatible materials and can be readily 
adjusted to proper condyle head orientation with respect to the glenoid 
fossa. 
It is a further object of the invention to provide a mandibular prosthesis 
for repair and replacement of the condylar process which is of relatively 
simple and economic construction from materials which have been 
established as structurally suitable and biocompatible under high stress 
and force conditions of the type experienced by the TM joint of humans. 
Other objects and advantages of the invention will become apparent through 
the following specification when considered in the light of the attached 
drawing figures. 
SUMMARY OF THE INVENTION 
The present invention relates to a mandibular prosthetic appliance for the 
repair and replacement of the condylar process of the human mandible. More 
specifically, the invention relates to a biocompatible, structurally 
sound, mandibular prosthesis structure (hereinafter referred to as a 
"condylar replacement prosthesis") for the repair and replacement of the 
condylar process or condyle component of the temporomandibular joint (TMJ) 
complex. The TM joint complex on each side of the mandible is basically 
comprised of the knob-shaped condyle prominence of the ramus, the 
meniscus, the cup-shaped glenold fossa formed in the temporal bone of the 
skull, and supporting and connecting structures. 
The unique condylar replacement prosthesis of the invention is comprised of 
an upper synthetic condyle replacement member, including its supporting 
stem portion, and a lower perforated metal ramus attachment fixture within 
which the stem portion of the condylar replacement member is adjustably 
positioned and retained. The synthetic condylar replacement member, with 
its lower stem portion is preferably fabricated of "Delrin" acetal resin. 
Delrin (a registered trademark of DuPont de Nemours Co.) is a 
thermoplastic polymer of the polyacetal family of compounds with the 
chemical name polyoxymethylene or polyformaldehyde. This material has been 
widely used in engineering in applications requiring strength, creep 
resistance, and stability over time. In the medical field Delrin has been 
found to be non-toxic and biocompatible with respect to hard and soft 
tissues of the human body and the material has been used for many years in 
total hip replacement procedures with only a few instances of material 
rejection or required removal because of excessive wear. The knob-shaped 
head portion of the synthetic condylar replacement member of the invention 
is provided in a series of typical condyle shapes and sizes for proper 
selection and fitment with respect to the glenoid fossa by the surgeon 
during the prosthesis placement surgical procedure. 
The ramus attachment fixture of the present condylar replacement prosthesis 
is preferably fabricated from a panel of relatively thin perforated 
biocompatible metallic sheet material, particularly titanium mesh sheet 
material. Pure titanium is recognized as an unequaled implant material in 
use clinically for over 30 years with no documented cases of allergic 
reaction. Further, pure titanium is the material of choice in craniofacial 
reconstructive surgery when non-removal of the implanted prosthesis is 
indicated. As an implantable material, pure titanium is preferred because 
its low density (weight) and elastic modulus (stiffness) characteristics 
are approximately one-half that of stainless steel and cobalt-chrome 
alloys and the material is corrosion resistant and pliable. 
A preferred form of perforated titanium mesh sheet material, for 
fabrication of the ramus attachment fixture of the present invention, is 
sheet material with substantially square perforations arranged uniformly 
in rows and lines so that bone screws may be applied through the 
perforations and into underlying bone without significant protrusion of 
the head portion of such screws, Alternatively, the perforated titanium 
mesh sheet material forming the ramus attachment fixture may include 
chamfered square and round screw holes arranged in uniform rows and lines. 
The perforated metallic mesh ramus attachment fixture of the condylar 
replacement prosthesis of the present invention is formed with: 
i) a cylindrical sleeve portion (for seating of the stem portion of the 
synthetic condyle replacement member) extending along the length of the 
posterior edge of the fixture; 
ii) an outer ramus mount panel projecting forwardly from the sleeve portion 
(in a plane tangent to such sleeve portion) for bone screw attachment of 
the fixture to the ramus at the lateral side thereof; 
iii) an upper panel portion extending forwardly from the upper sleeve 
portion (closing the upper peripheral portion of the cylindrical sleeve) 
adjacent the ramus mount panel and affixed thereto for attachment with the 
ramus mount panel to the ramus; and 
iv) a lower ramus clamping panel portion extending forwardly from the lower 
portion of the sleeve and spaced from the ramus mount panel for 
positioning on the medial side of the ramus and stabilizing the condylar 
replacement prosthesis in its mounted position on the ramus stump. 
Surgical placement of the condylar replacement prosthesis of the invention 
involves the following procedures: 
a) The synthetic condylar replacement member (with its condyle head size 
and shape appropriately selected for fitment to the glencid fossa) of the 
replacement prothesis is inserted (in its cylindrical stem portion) into 
the matching cylindrical sleeve portion of the ramus attachment fixture. 
b) The ramus attachment fixture is mounted in appropriate TMJ orientation 
to the ramus stump via bone screws applied through selected mesh 
perforations of the ramus mount panel and into the lateral side of the 
ramus stump. Positioning of the attachment fixture must be such that the 
bottom surface of the stem portion of the synthetic condylar replacement 
member will interface with and rest upon the upper surface of the 
horizontal step in the ramus as surgically prepared by the surgeon. 
c) The lower ramus clamping panel of the fixture is pinched inwardly into 
contact with the medial side of the ramus stump for stabilization of the 
fixture with respect to the ramus. 
d) The synthetic condyle replacement member of the replacement prosthesis 
(with its stem portion resting on the step cut in the ramus) is adjusted 
in its rotational orientation within the supporting cylindrical sleeve 
portion of the attachment fixture. 
e) Finally, one or more bone screws are applied through mesh perforations 
on the lateral side of the upper part of the fixture sleeve and into the 
stem portion of the condyle replacement member to lock the condyle 
replacement member in appropriate TMJ operating position.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring initially to FIG. 1 there is illustrated a human skull 10 showing 
the mandible (lower jaw bone) 12 in its closed position and as having a 
generally horizontal body portion with an anterior prominence (mandibular 
symphysis) 14 defining the chin in the facial structure. A branch of the 
mandible or ramus portion 16 extends upwardly and rearwardly at the 
posterior end of the body portion of the mandible. As shown in FIG. 2, the 
mandible 12 is U-shaped with like posterior ramus portions 16. The upper 
section of the ramus portions of the normal human mandible terminate in a 
rearward condyloid process or condyle 18 (the right condyle being shown 
severed from its ramus portion) and a forward coronoid process 20, the 
condyloid process and coronoid process being separated by the sigmoid 
notch 22. 
In accordance with the present invention (and as shown in FIGS. 1 and 2), 
there is affixed to the left-side ramus an artificial condylar replacement 
prosthesis 30 which is described in detail hereinafter. These figures show 
the lateral side of the mounted prosthesis. FIG. 3 is a medial (inside) 
partial view of the left-side ramus 16 of the mandible 12 of FIG. 2 with 
the artificial condylar replacement prosthesis 30 mounted thereto and 
shows the medial side of the mounted prosthesis. 
FIG. 4 is a longitudinal view of the medial side of the assembled 
artificial condylar replacement prosthesis 30 per se and FIG. 5 is an 
exploded view of the prosthesis showing the two components thereof, i.e., 
the upper synthetic condylar replacement member 32 and the lower ramus 
attachment fixture 34. The condylar replacement member 32 is preferably 
fabricated of "Delrin" acetal resin and is comprised of an upper 
knob-shaped head portion 32a and a lower stem portion 32b. As previously 
indicated, the knob-shaped head portion 32a of the replacement member is 
provided in a series of shapes and sizes to replicate natural human 
condyles for proper fitment with respect to the glenold fossa of the TM 
joint complex. Selection of the appropriate condylar replacement member is 
made by the surgeon from x-ray, MRI and CT scans of the natural condyle of 
the patient with final selection determination by the surgeon during the 
prosthesis placement surgical procedure. 
The ramus attachment fixture 34 of the condylar replacement member 30 is, 
as previously indicated, preferably fabricated from thin perforated 
biocompatible metallic sheet material, particularly titanium mesh sheet 
material. In the figures the attachment fixture is shown to be fabricated 
of perforated metallic sheet material in which the perforations are 
substantially square openings arranged uniformly in rows and lines. As 
clearly shown in FIGS. 4 and 5, the ramus attachment fixture 34 is 
comprised of an outer ramus mounting panel 36, a cylindrical sleeve 
portion 38, an upper panel portion 40 extending from the upper sleeve 
portion, and a lower ramus clamping panel portion 42. FIG. 6 is a cross 
section view of the ramus attachment fixture 34 of FIG. 5 taken on line 
6--6 of FIG. 5 showing the relationship of the mounting panel portion 36 
and clamping panel portion 42 with respect to the cylindrical sleeve 
portion 34, FIG. 7 is a top view of the ramus attachment fixture 34 of 
FIG. 5 showing the closed upper cylindrical sleeve portion 38 (holds the 
stem portion 32b of the condylar replacement member 32) and upper panel 
portion 40. 
The cylindrical sleeve portion 38 of attachment fixture 34 is for seating 
the stem portion of the synthetic condyle replacement member 32 and 
extends along the length of the proximal edge of the fixture. The outer 
ramus mounting panel 36 projects forwardly from the sleeve portion 38 in a 
plane substantially tangent to the sleeve portion. The upper panel portion 
40 of the fixture extends forwardly from the upper sleeve portion and 
closes the upper peripheral portion of the sleeve 38. The panel portion 40 
rests in interfacing contact with the mounting panel 36, as shown in the 
top view of FIG. 7, with its perforations in alignment with the 
perforations of panel 36. The lower ramus clamping panel 42 extends 
forwardly from the lower portion of the sleeve portion 38 of fixture 34 
and is spaced from the ramus mounting pane 36 for positioning on the 
medial side of the ramus stump for stabilizing the condylar replacement 
prosthesis 30 in its mounted position on the ramus stump. 
Surgical placement of the condylar replacement prosthesis of the invention 
involves the following procedures: 
a) The synthetic condylar replacement member 32 of the replacement 
prosthesis 30 (with the head portion 32a of the replacement member 
appropriately selected for fitment to the glenoid fossa of the TN joint 
complex) is inserted (in its cylindrical stem portion 32b) into the 
matching cylindrical sleeve portion 38 of the ramus attachment fixture 34. 
As such, the replacement member may be adjustably rotated and positioned 
vertically within the sleeve. 
b) The ramus attachment fixture 34 is mounted in appropriate TMJ 
orientation to the ramus stump 16 via bone screws 50 applied through 
selected mesh perforations of the ramus mounting panel 36 of the fixture 
and into the lateral surface of the stump. In practice, a first bone screw 
is applied and tightened only to the extent that the condylar replacement 
member 32 of the fixture 34 can be rotationally moved to a position 
whereat proper polar axis alignment of the condyle replacement member 32 
is achieved with respect to the glencid fossa of the TM joint complex. 
After such alignment additional bone screws are applied and tightened to a 
proper torque extent. 
c) The lower ramus clamping panel 42 of the ramus attachment fixture 34 is 
pinched inwardly into contact with the medial side of the ramus stump for 
stabilization of the fixture with respect to the ramus. 
d) The synthetic condyle replacement member 32 of the replacement 
prosthesis 30 is adjusted to its final rotational orientation within the 
supporting cylindrical sleeve portion 38 of the attachment fixture 34 so 
that the artificial head portion 32a thereof is in proper position in the 
TM joint complex for proper operation of the mandible. 
e) Finally, one or more bone screws 52 are applied through the mesh 
perforations on the lateral side of the upper part of the sleeve portion 
38 of the attachment fixture 34 and into the stem portion 32b condyle 
replacement member 32 to lock the replacement member 32 in its proper 
position. 
As previously indicated, FIG. 2 has shown the human mandible 12 as U-shaped 
with two like ascending ramus portions 16. Upon the left side of the 
illustrated mandible is mounted a left-side condylar replacement 
prosthesis 30 in accordance with the present invention. The posterior 
right side of the mandible is shown to have the right-side condylar 
process 18 severed from the ramus 16, leaving a ramus stump portion 16a 
cut with a horizontal plateau, in preparation for the placement of a 
right-side condylar replacement prosthesis (not shown). A right-side 
condylar replacement prosthesis would, in accordance with the invention, 
comprise a mirror image of the prosthesis shown in FIGS. 1-7. With the 
ramus stump 16a prepared as shown, a mirror image prosthesis would be 
seated on the ramus with the lower edge of the upper closed cylindrical 
sleeve portion of the prosthesis abutting the horizontal plateau cut of 
the ramus stump and the mounting panel and clamping panel of the 
prosthesis straddling the ramus. 
While the invention has been described in connection with a particular 
structural embodiment of a mandibular prosthesis for replacement of a 
diseased or fractured condylar process portion of the TM joint complex of 
a human mandible, many modifications of the invention will be apparent to 
those skilled in the art. Accordingly, such modifications are to be 
included within the spirit and scope of the invention as defined by the 
following claims.