Methods and apparatus for arthroscopic prosthetic knee replacement

Methods and apparatus for prosthetic knee replacement permit preparation of tibial plateau and femoral condyle surfaces and implant of tibial and femoral protheses components with the use of arthroscopic surgical techniques. The bone surfaces are resected by moving a rotating milling cutter longitudinally across the bone surface and moving the rotating milling cutter substantially laterally across the bone. Cement is supplied between the prostheses and the bone surfaces after positioning of the prostheses on the bone, and cement bonding is enhanced by applying suction to the bone to draw the cement into the bone.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention pertains to resection of bones for receiving 
prosthetic components of particular use in knee replacement procedures 
and, more specifically, to methods and apparatus for arthroscopic knee 
replacement. 
2. Discussion of the Prior Art 
Prosthetic replacement of the knee is a procedure of substantial importance 
to recreate the knee joint with a pain-free functional arc of motion and 
antero-posterior and varus-valgus stability. The knee is, basically, 
formed of medial and lateral tibial plateaus, medial and lateral femoral 
condyles and menisci between the tibial plateaus and the femoral condyles 
along with the patella which covers the anterior surface of the knee, and 
prosthetic replacement of the knee as described herein relates to the 
tibial plateaus, the femoral condyles and the menisci. Various types of 
prostheses are presently available, as described in detail in Replacement 
of the Knee, Laskin, Denham and Apley, Springer-Verlag Berlin Heidelberg, 
1984, and are commonly grouped as partial or unicompartmental replacements 
of the medial or lateral portion of the tibio-femoral joint, surface 
replacements to prevent contact between worn surfaces and jack the joint 
surfaces apart, linked joints and fixed hinge joints. The type of 
prothesis employed must be matched to the needs of the patient. By 
selecting the proper prothesis, antero-posterior and varus-valgus 
stability can be achieved by prosthetic replacement coupled with bone 
surfacing or resection. In the past, prosthetic replacement has been a 
last resort in treatment for knee problems due to the facts that prior art 
protheses and surgical procedures have not led to reliable, close to 
natural, results and the open surgery required results in great trauma and 
substantial recovery time. Much effort has been expended in attempts to 
improve the accuracy with which articular joint surfaces can be positioned 
with leg alignment; however, procedures and apparatus available at this 
time do not provide the required accuracy to restore normal leg alignment 
and prevent early failure of the prothesis. 
Open surgery required for prior art prosthetic replacements typically 
necessitates a long incision, on the order of ten inches, along the 
anterior midline of the knee from above the patella to below the tibial 
tubercle followed by a deep dissection around the medial border of the 
patella and along the patellar ligament to the tibial tubercle with 
detachment of the medial third of the quadriceps attachment from the upper 
border of the patella. The tendinous margin is then pulled downwards and 
medially while the patella is pulled downwards and laterally. The 
quadriceps tendon is then split, and the patella is displaced laterally 
and everted. While the above is a simplified explanation of open knee 
surgery, it serves to explain the substantial trauma and recovery time 
associated therewith. Arthroscopic surgery has been used for many surgical 
procedures on the knee to avoid open surgery with great success; however, 
the obstacles presented by articular bone surface resecting or shaping to 
receive an implant coupled with the need for precise positioning and 
alignment of the prostheses has been insurmountable with arthroscopic 
procedures prior to the present invention. Not only is there a great need 
for an arthroscopic prosthetic knee replacement procedure but there is 
also a great need for improvement in the accuracy of prosthesis placement 
to restore normal leg alignment. 
SUMMARY OF THE INVENTION 
Accordingly, it is a primary object of the present invention to overcome 
the above mentioned disadvantages associated with prior art prosthetic 
knee replacement surgical procedures with an arthroscopic prosthetic knee 
replacement. 
Another object of the present invention is to accurately resect tibial 
plateau and femoral condyle planar surfaces relative to each other such 
that the tibial plateau and femoral condyle surfaces are constrained to be 
disposed in planes perpendicular to a substantially vertical reference 
plane. 
A further object of the present invention is to cement a prosthesis to a 
tissue surface after the prosthesis is accurately placed on the tissue 
surface. 
An additional object of the present invention is to perform a least 
invasive prosthetic knee replacement with the use of arthroscopy and 
requiring only arthroscopic size portals. 
The present invention has another object in the performing of all 
procedures for a prosthetic knee replacement, including surface 
preparation, fitting and implanting, arthroscopically through small 
portals enlarged only for insertion of the final components. 
Yet an additional object of the present invention is to arthroscopically 
resect tibial plateau and femoral condyle surfaces using existing surface 
anatomy as a reference point. 
A further object of the present invention is to improve the mechanical bond 
created by cement between a prosthesis and a bone surface by applying 
suction to the bone to draw the cement into the bone. 
Some of the advantages of the present invention over prior art prosthetic 
knee replacements are that, by using arthroscopic surgical techniques and 
small portals in place of the long incisions required for open knee 
procedures, trauma and recovery time are substantially reduced, alignment 
of the tibial and femoral prosthesis components is assured by fixing the 
femoral cutting jig with reference to the tibial cutting jig and, 
therefore, resecting the femoral condyle with reference to the resected 
tibial plateau, the knee is restored to a normal, healthy condition by 
resecting the tibial plateau and the tibial condyle using the existing 
surface anatomy as a reference point, and prostheses are cemented after 
accurate positioning of the prostheses on the bone. 
Generally, the present invention contemplates the use of a milling cutter 
to prepare a bone surface to receive a prosthesis such that bone surfaces 
can be resected through small portals allowing prosthesis implantation 
using arthroscopic surgical techniques and, more particularly, allowing 
arthroscopic, unicompartmental, prosthetic total knee replacement. Tibial 
and femoral prosthesis components are bonded to the bone surfaces by 
injecting cement after the components are accurately positioned on the 
bone, the cement being injected through the components to be received in 
chambers defined by recesses in the fixation surfaces of the components 
and the cement bond being enhanced by applying suction to the bone to draw 
the cement into the bone. 
Other objects and advantages of the present invention will become apparent 
from the following description of the preferred embodiment taken in 
conjunction with the accompanying drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
The apparatus and method for prosthetic knee replacement in accordance with 
the present invention requires only small portals to perform all bone and 
tissue preparation procedures as well as implanting the prosthetic tibial 
and femoral components and cementing the components in place. Accordingly, 
prosthetic knee replacement in accordance with the present invention can 
be performed with the use of arthroscopic surgical procedures. By "portal" 
is meant a puncture or stab wound of the type made by a plunge cut with a 
scalpel or trocar and of the type commonly used in conventional 
arthoscopic procedures, the size of the portal being just large enough to 
allow insertion of instruments. 
A tibial jig 40 in accordance with the present invention is illustrated in 
FIG. 1 and includes a lower V-block 42 adapted to rest just above the 
malleoli at the ankle and an upper V-block 44 adapted to be secured to the 
tibia just below the tibial tubercle. Lower V-block 42 is connected to a 
rod 46 telescopingly received within a tube 48 connected to upper V-block 
44 which is formed of a pair of angled members having a plurality of holes 
50 therein to receive screws 52 extending herethrough and into the tibia 
to securely mount the tibial jig thereon. As best shown in FIG. 2, tube 48 
has spaced arms 54 and 56 terminating at the angled members of upper 
V-block 44, and an angular adjustment member 58 has a tongue 60 disposed 
between members 54 and 56 with a hole 62 therein for receiving an 
adjustment screw 64 extending through corresponding holes in members 54 
and 56. In this manner, the angular adjustment member 58 can be pivoted 
about screw 64 to a desired position and the screw tightened to hold the 
angular adjustment member in place. A longitudinal adjustment block 66 has 
a dovetail slot 68 therein to receive a dovetail 70 on member 58, and a 
longitudinal adjustment screw 72 is held in a non-rotating manner in block 
66 and carries a head 74 having a dovetail slot 76 therein. Block 66 has 
spaced arms between which is mounted a thumbwheel 78 threadedly engaging 
adjustment screw 72 such that rotation of thumbwheel 78 causes 
longitudinal axial movement of the screw and the head. A block 80 has a 
dovetail 82 received in slot 76 and mounts a cutter platform generally 
indicated at 84. As shown in FIGS. 3 and 3a, a longitudinal or depth of 
cut gauge 86 is mounted on an extension 88 of block 66 and carries indicia 
90 allowing registration with an index mark on screw 72 to indicate the 
depth of a cut being made, as will be explained in more detail 
hereinafter. The gauge has a zero center mark with indicia extending in 
either direction therefrom in millimeter graduations. 
The platform 84 includes a semi-circular plate 92 having a curved 
peripheral edge 94 and a dovetail 96 slidably received in a dovetail slot 
98 in block 80 to permit movement of the platform in a lateral direction 
perpendicular to the longitudinal movement of screw 72. A linear slide 
member 100 has a distal end 102 pivotally mounted centrally on plate 92 
and carries a toothed rack 104 longitudinally thereon. The slide member 
100 extends substantially beyond the peripheral edge 94 of plate 92 and 
carries on its back side a clamp assembly including a lever 106 pivotally 
mounted on ears 108 secured to the slide member, the lever 106 having a 
clamping end 110 and an operating end 112 as best shown in FIG. 8. A 
trigger like member 114 is pivotally mounted on a lug 116 extending from 
the slide member and has a flat portion engaging the operating end 112 of 
lever 106 which is biased against the trigger by means of a compression 
spring 118. Accordingly, when trigger 114 is moved toward the slide member 
(rotated clock-wise looking at FIG. 8) the operating end 112 of lever 106 
is moved toward the slide member causing the clamping end 110 to move away 
from the peripheral edge 94 of plate 92 thereby allowing pivotal movement 
of the slide member relative to the plate. When the trigger 114 is 
released, the spring 118 returns the clamping end 110 to engagement with 
the plate to hold the slide member in the selected pivotal position. 
The slide member has an elongated dovetail 121 received in a slot 122 in a 
housing 124 of a cutter module generally indicated at 126. A pinion 128 
having teeth for engaging rack 104 is mounted on an axle journaled through 
housing 124 to terminate at handwheels 132 on either side of the housing. 
A pneumatic motor 134 has a proximal end receiving drive and exhaust 
conduits 136 and a distal end engaging the shaft of a milling cutter 138 
as best shown in FIG. 8. The motor is driven by pressurized fluid, such as 
nitrogen or air; and, when the drive fluid is provided at 100 psi, the 
motor speed and torque are 4000 rpm and 50 oz-inch, respectively. A 
chamber 140 is formed around the drive coupling and has a port 142 for 
connection to a source of suction, the proximal end of the milling cutter 
138 having a hole 144 therein for communicating with the chamber and the 
milling cutter 138 being rotatably supported at the distal end of the 
chamber by suitable bearing and journal structure. Stops 146 and 148 are 
movably secured to the peripheral edge 94 of plate 92 on opposite sides of 
slide member 100; and, as shown in FIG. 7a, are formed of set screws 150 
for engaging the plate 92. 
The milling cutter 138, as best shown in FIGS. 9, 10 and 10a, includes a 
shaft having a proximal end 152 for engaging a locking collet assembly in 
chamber 140 to be driven by the pneumatic motor, the shaft being hollow to 
establish communication between hole 144 in the proximal end thereof and 
holes 154 disposed in the distal portion thereof. The distal portion of 
the milling cutter includes a body 156 having a plurality of helical 
cutting edges 158 extending therealong, and at least one hole 154 is 
disposed between each pair of body cutting edges 158. As shown in FIG. 10, 
four equally spaced cutting edges are disposed on the fluted body 156, and 
holes 154 communicate with a passage 160 formed by the hollow shaft of the 
milling cutter. Cutting edges 162 are disposed at the distal end of the 
milling cutter in a plane extending transverse to the longitudinal axis of 
the milling cutter, and each of the body cutting edges 158 extends from 
one of the distal end cutting edges 162. The milling cutter preferably has 
a diameter of 7 mm and the body cutting edges preferably have 
substantially radial leading edges. 
The operation of the apparatus described above to resect a tibial plateau 
for unicompartmental prosthetic knee replacement utilizing arthroscopic 
surgical techniques will be described with reference to FIGS. 1 and 3. As 
previously described, tibial jig 40 is secured to the tibia by screws 52 
extending through V-block 44 and into the tibia with the upper and lower 
V-blocks disposed just below the tibial tubercle and just above the 
malleoli at the ankle, respectively, with a set screw 163 provided to 
maintain the position of telescoping members 46 and 48. A portal 164 is 
formed in the knee for insertion of an arthroscope 166 for viewing of the 
knee and the surgical procedure, while a portal 168 is formed in the 
tissue adjacent the tibial plateau, FIG. 1 illustrating the portal 168 for 
use in resecting the medial tibial plateau of the left leg. With the 
tibial jig 40 secured in alignment with the tibia, the apparatus is 
assembled as illustrated in FIG. 3 with the exception that the cutter 
module is not mounted on the slide member 100 but rather a stylus module 
170, as illustrated in FIG. 26, is mounted thereon. The stylus module 170 
includes a housing having a dovetail slot for receiving the dovetail 120 
of the slide member and mounts a stylus 172 having four equally spaced 
positions controlled by detents, not shown, within the housing. The stylus 
has a curved radially extending tip 174 that can be positioned via the 
detents to extend up, down or to either side. The radial extension of the 
stylus 174 is preferably equal to the radius of the milling cutter, e.g., 
3.5 mm, and the housing of the stylus module positions the stylus at the 
same position at which the milling cutter is positioned when the cutter 
module is received on the slide member. With the stylus tip turned down, 
the posterior and anterior edges of the tibial plateau are contacted with 
the stylus, and angular adjustment block 58 is pivoted about screw 64 to 
align the platform with the natural tilt of the tibial plateau as sensed 
by the stylus, the natural tilt being normally between 3.degree. and 
10.degree. posteriorly. Once the natural tilt is established, the stylus 
is rotated 90 such that the tip 174 is turned to the right, and the tip of 
the stylus is moved by sliding the plate 92 in block 80 until the tip of 
the stylus contacts the tibial eminence 176 as illustrated in FIG. 27. 
Once the tibial eminence has been located, a screw, not shown, is 
tightened to secure the lateral position of the platform. The slide member 
100 is centrally positioned on the plate 92 during this procedure, and the 
stop 148 is moved to abut the slide member 100 to prevent pivotal movement 
of the slide member and the milling cutter mill clockwise looking at FIG. 
7. With the tip 174 of the stylus turned down, the lowest point of contact 
of the tip on the tibial plateau is located; and, with the stylus at this 
contact point, thumbwheel 78 is locked in place to control the position of 
the resection to be performed, it being noted that, due to the dimensional 
relationship between the cutter module and the stylus module, the milling 
cutter will be aligned with the lowest point on the tibial plateau. As 
shown in dashed lines in FIG. 27, prior to the alignment steps, the 
anterior portion of the meniscus or cartilage has been removed by normal 
arthroscopic techniques leaving a posterior segment indicated at 178 such 
that during the resection procedure, the posterior portion of the meniscus 
provides a cushion to provide the surgeon with an indication of the 
location of the posterior edge of the tibial plateau. 
To resect the tibial plateau, the stylus module is removed and the cutter 
module is placed thereon as illustrated in FIG. 3; and, since angular, 
lateral and longitudinal adjustments have already been made and set in 
place, only linear and pivotal movements of the milling cutter can be made 
and such movements can be made only in a single plane. With reference to 
FIGS. 4 and 5, it can be seen that initial forward movement of the milling 
cutter produces a longitudinal plunge cut along the tibial eminence 176 to 
produce a trough across the tibial plateau as indicated at 180, it being 
noted that the milling cutter cuts on its distal end as well as along the 
fluted body thereof. After the first longitudinal cut has been made, the 
trigger 114 is released allowing pivotal movement of the slide member 
slightly; and, after the trigger is released to clamp the slide member in 
position, a second longitudinal cut is made by linear movement of the 
milling cutter as indicated at 182. This procedure is repeated until the 
surface of the tibial plateau is covered with troughs having ridges 184 
therebetween. The trigger 114 is now depressed to release the slide 
member; and, with the milling cutter disposed over the tibial plateau, the 
milling cutter is pivoted back and forth to sweep the milling cutter over 
the tibial plateau removing the ridges, the sweeping movement being 
substantially transverse to the longitudinal movements of the milling 
cutter to form the troughs. During the resecting procedure, suction is 
applied to port 142 such that bone chips are evacuated via holes 154 and 
passage 160 through the hollow milling cutter. The suction also serves to 
cool the surgical site and prevent cavitation. 
Once the tibial plateau has been resected, the cutter module is removed 
from the platform, and the platform is removed from block 80. An alignment 
bridge 186, as illustrated in FIG. 12, is then coupled with block 80 as 
illustrated in FIGS. 11 and 13, it being noted that block 80 remains fixed 
relative to the tibia and, therefore, the resected planar tibial plateau. 
The alignment bridge 186 includes a dovetail slide 188 received in the 
slot 98 in block 80, and an arm 190 extends at an angle of 45.degree. 
between slide 188 and a drill guide 192 having parallel bores 194 and 196 
therethrough. Accordingly, the bores 194 and 196 will be disposed in a 
plane transverse to the plane of the resected tibial plateau. With the leg 
in full extension, as illustrated in FIGS. 11 and 13, inserts 198 and 200 
are passed through bores 194 and 196, respectively, to provide elongated 
guides for drilling parallel bores through the femur. The bores are 
drilled through the femur using conventional orthopedic techniques; and, 
after the bores are drilled through the femur, threaded rods 204 are 
passed through each bore as illustrated in FIG. 14. As shown in FIG. 15, 
one of the threaded rods 204 is preferably hollow having a passage 206 
therethrough providing communication between its end and holes 208 
centrally located therein. Threaded sleeves 210 are disposed on the outer 
ends of each rod in threaded engagement with the rods while loosely 
sliding sleeves 212 are disposed between sleeves 210 and the femur, the 
sleeves being illustrated in FIG. 16 and shown in position relative to the 
femur in FIG. 14. With the sleeves tightened in place and the rods passing 
through the epicondylar region of the femur, a support for resecting the 
femoral condyle is established relative to the resected tibial plateau 
since the rods are disposed in a plane perpendicular to the planar tibial 
plateau. With the rods in place, a femoral support base 214 is rigidly 
attached to the rods to prevent any deflection or twisting of the rods. 
The femoral support base 214 includes a U-shaped member 216 having upper 
ends secured saddles 218 each of which has a cylindrical protrusion 220 
extending upwardly therefrom and side walls 219 spaced from the 
cylindrical protrusion to allow the sleeves 210 to fit therebetween. 
Conical washers 222 are secured over the sleeves by means of screws 224 
received in threaded holes 226 in the saddles 218 such that the washers 
abut the sleeves to firmly hold the rods in parallel position. 
A femoral cutting jig 228 is mounted to the femoral support base 214 via 
threaded posts 230 extending through the cylindrical protrusions 220 to 
receive threaded nuts 232 tightening the femoral cutting jig in rigid 
position relative to the femoral support base. The femoral cutting jig 
includes a U-shaped member 234 having opposite legs pivotally mounted on 
flanges 236 each of which is rigidly secured to the femoral support base 
via threaded post 230. As best shown in FIGS. 20, 21 and 22, each of the 
flanges 236 has holes 238, 240 and 242 therein positioned relative to the 
pivotal axis indicated at 244 to position a support 246 rigidly connected 
with the U-shaped member 234 in a plane parallel to the plane passing 
through the rods through the femur as illustrated in FIG. 21, a plane 
perpendicular to the plane passing through the rods as illustrated in FIG. 
20, and a plane positioned at an angle of 45.degree. to the plane passing 
through the rods as illustrated in FIG. 22. The position of the U-shaped 
member and therefore the support 246 is controlled by means of spring 
loaded detents mounted on flanges 248 secured to the opposite ends of the 
U-shaped member. As shown in FIG. 23, detents 250 are biased inwardly to 
extend through holes 238, 240 or 242 with which they are aligned, and can 
be withdrawn by twisting end 252 to cause the end to cam outwardly as 
shown in phantom compressing a spring 254 to move the detent out of the 
hole. Accordingly, the femoral cutting jig ca be accurately positioned in 
either of the three positions shown in FIGS. 20, 21 and 22 by manipulating 
the detents and pivoting the U-shaped member relative to the femoral 
support base. The femoral cutting jig illustrated in FIG. 19 differs 
slightly from that illustrated in FIGS. 20, 21 and 22 in that the support 
246 is secured at an angle to the U-shaped member 234; however, the 
operation is the same in that positioning of the femoral cutting jig only 
requires accurate positioning of the support 246 to which the longitudinal 
adjustment block 66 is attached to mount the cutting platform and the 
cutting module in a plane perpendicular to support 246 in the same manner 
as described above with respect to mounting of the cutting platform and 
the cutting module on angular adjustment block 58 mounted on the tibial 
jig. FIG. 19 illustrates the milling cutter positioned at an angle of 
45.degree. to the plane of the rods 204 through the femur and further 
illustrates, in phantom, the milling cutter positioned in planes 
perpendicular and parallel to the plane of the rods 204. Since the plane 
of the rods 20 is parallel to the planar resected tibial plateau, the 
milling cutter is constrained to move only in planes parallel to a 
reference plane extending perpendicular to the plane of the resected 
tibial plateau. 
To resect the femoral condyle, the stylus module 170 is mounted on the 
slide member 100 with the stylus 172 turned upward as illustrated at 256 
in FIG. 29 and the slide member positioned in a plane parallel to the 
resected tibial plateau plane, and the stylus is moved to contact the 
lowermost point on the posterior surface of the femoral condyle. Once this 
point is located, the depth gauge 86 is moved to align the "zero" point 
with the index line on the screw 72. With the depth gauge so aligned, the 
stylus module is removed, and the thumbwheel 78 is rotated to move the 
cutting platform 7 millimeters toward the femoral condyle as indicated by 
the gauge 86. With the depth of cut now set and the lateral position set 
by viewing the position of the stylus via the arthroscope, the cutting 
module is positioned on the slide member and the posterior portion of the 
femoral condyle is resected in the same manner as described above with 
respect to the tibial plateau, that is, by forming a plurality of 
longitudinal troughs in the bone and removing the ridges therebetween by 
sweeping the milling cutter. With reference to FIG. 20, it can be seen 
that resecting of the posterior surface of the femoral condyle is 
accomplished by passing the milling cutter and the stylus through the same 
portal 168 utilized to resect the tibial plateau. 
After resection of the posterior surface of the femoral condyle, the distal 
surface of the femoral condyle is resected by moving the femoral cutting 
jig to position the platform in a plane perpendicular to the plane of the 
rods passing through the femur and the plane of the resected posterior 
surface of the femoral condyle. The stylus module and the depth gauge are 
used in the same manner as described with respect to the resecting of the 
posterior surface; however, as illustrated in FIG. 21, a second portal 258 
disposed between an inch and an inch and a half above portal 168 is 
utilized for the distal surface cutting procedure. As shown in FIG. 29, 
the stylus is turned toward the condyle as indicated at 260; and, when the 
resecting procedure is completed, the resected planar distal surface will 
be perpendicular to the resected planar posterior surface. Resection of 
the distal surface is accomplished in the same manner as described above 
with respect to the tibial plateau and the posterior surface. 
Once resection of the distal surface is completed, the femoral cutting jig 
is pivoted to the position illustrated in FIG. 22 such that the platform 
is disposed in a plane at an angle of 45.degree. to the distal and 
posterior resected surfaces. The stylus is mounted on the platform and 
passed through portal 258 to contact the uncut portion of the femoral 
condyle between the resected posterior and distal surfaces as shown at 
262, and the depth gauge and cutter module are utilized in the same manner 
as described above to cut a chamfer surface between the distal and 
posterior surfaces, the chamfer surface being disposed in a plane at an 
angle of 45.degree. to the planes of the distal and posterior surfaces. A 
plurality of semi-circular gauges 264, each having an anterior foot 266 
and a posterior foot 268, are provided; and, to determine the length of 
the chamfer cut, individual gauges are attached to a rod 270 inserted 
through portal 258 and aligned with the chamfer cut to determine the size 
of the femoral prothesis for use with the contoured femoral condyle. 
FIG. 24 illustrates the medial compartment of the knee after resection, and 
it will be appreciated that the planes of each of the posterior, distal 
and chamfer cuts on the femoral condyle are parallel to a reference plane 
perpendicular to the plane of the tibial plateau, the reference plane 
being substantially vertical thereby producing a normal healthy knee 
joint. The resected planar tibial plateau is indicated at 272, the 
posterior planar femoral condyle cut is indicated at 274, the distal 
planar femoral condyle cut is indicated at 276 and the chamfer planar 
femoral condyle cut is indicated at 278. Once all of the resections have 
been performed as described above, the area between portals 168 and 258 is 
incised to increase the size of the portal to about one and one-half 
inches as indicated at 280. The tibial jig is removed once the rods are 
inserted in the femur to establish the femoral support base; and, once the 
resections are completed, the femoral support base and the femoral cutting 
jig are removed. A drill guide 282 mounted on a rod 284 is inserted into 
the joint through portal 280, the drill guide having a distal portion for 
abutting distal planar surface 276 and a chamfer portion 286 for abutting 
chamfer surface 278, the angle between portions 286 and 288 being 
45.degree. to equal the angle between distal surface 276 and chamfer 
surface 278. With the guide 282 aligned on the prepared femoral condyle, 
spaced holes 290 are drilled in the distal surface. Since the same amount 
of bone has been removed from each cut during contouring of the femoral 
condyle, a femoral prothesis component 292 can be implanted on the femoral 
condyle reproducing the natural condyle. Femoral component 292 has a 
polycentric bearing surface 294 with an inner fixation surface 296 for 
engaging the posterior, distal and chamfer surfaces, and spaced tapered 
posts 298 extend from a distal portion of the femoral component to be 
received in holes 290. A channel 300 is formed in the femoral component to 
communicate with a recess 302 formed in the fixation surface 296 such that 
the femoral component can be installed in proper position on the prepared 
femoral condyle with the posts 298 received in the holes 290; and, 
thereafter, cement can be introduced between the femoral component and the 
bone via channel 300, the cement filling the recess 302 and producing a 
mechanical bond with the bone. The mechanical bond of the cement with the 
bone is enhanced by applying suction to rod 204, the suction being 
communicated via passage 206 and holes 208 and through the porous bone to 
draw the cement into the bone. 
Prior to installation of the final tibial prothesis component, a trial tray 
similar in shape to tibial component 304 illustrated in FIG. 24 is placed 
on tibial plateau 272 via portal 280 to obtain the correct size, and 
various bearing inserts similar to bearing insert 306 illustrated in FIG. 
24 are positioned in cavities in the tray to provide the desired tibial 
component thickness allowing alignment of the femur and tibia with the 
femoral component bearing on the bearing insert. When the proper spacing 
is determined, a permanent tibial prothesis implant 304 is passed through 
portal 280 and secured to tibial plateau 272. The tibial component 304 has 
a cavity 308 in the upper surface thereof for receiving bearing insert 306 
in locking engagement, and, similar to femoral component 292, a recess 310 
is formed in a bottom fixation surface 312 and a channel 314 communicates 
therewith for supplying cement to the tibial component after the tibial 
component is placed on the tibial plateau. A bone screw passes through an 
angled hole 316 in an anterior portion of the tibial prothesis 304 to hold 
the prothesis o the tibial plateau. The tibial and femoral prosthesis 
components and the bearing insert are disclosed in an application filed 
concurrently herewith by the same inventors entitled "Knee Joint 
Prosthesis", the disclosure of which is incorporated herein by reference. 
In practice, removable trial femoral components can be placed on the 
femoral condyle to assist in selection of proper tibial component 
thickness, and either the tibial component or the femoral component can be 
cemented in place before the other. 
From the above, it will be appreciated that the method and apparatus of the 
present invention permits prosthetic knee replacement utilizing 
arthroscopic surgical procedures. Additionally, the method and apparatus 
provide advantages useful in open knee surgery also in that the cuts in 
accordance with the present invention are different for each individual 
since each cut is sensed from the surface and not from a previous cut 
thereby restoring a natural knee action in that making the cuts with 
reference to bone surfaces allows replication of the previous bone 
structure thereby not forcing alignment and allowing the compartment to be 
matched with the other compartments of the knee. Additionally, by 
establishing the femoral jig in the femur in relation to the tibial 
plateau, alignment of the femoral and tibial protheses is assured with 
bearing contact along a line laterally through the knee joint. The 
platform and cutting module permit the cutting action to be performed by 
the surgeon with only one hand allowing his second hand to move the 
arthroscope or to provide better viewing in open surgery. The resecting of 
bone using a pivoting movement of a cutter is particularly advantageous in 
that, by placing the pivot point just external of the body, small portals 
can be used in accordance with arthroscopic techniques. 
Inasmuch as the present invention is subject to many variations, 
modifications and changes in detail, the subject matter discussed above 
and shown in the accompanying drawings is intended to be illustrative only 
and not to be taken in a limiting sense.