Download presentation
1
APEX Knee Design Rationale
2
Design Intent Anatomic components Insert/femur size matching
Asymmetric femurs and trays Symmetric inserts Insert/femur size matching True posterior referencing femoral design Improved sizing for better fit Enhanced flexion
3
Design Intent Both cruciate sparing and cruciate sacrificing inserts
Dome patella Cemented and cementless components Simplified instrumentation
4
Femoral Components Six “basic” sizes Half sizes 2 + and 3+ Size M/L
A/P 1 58 54 2 62 2 + 60 3 66 3+ 64 4 70 5 75 6 80
5
SINGLE RADIUS
6
Plus Sizes - If Size 4 is too wide, switch to a 3+ femur
FEMORAL COMPONENTS Plus Sizes - If Size 4 is too wide, switch to a 3+ femur Same bone cuts Narrower Thinner Flange 3+ Uses Size 3 insert Same logic for Size 3 and 2 +
7
13 of 59 Knees were + sizes (22%) 12 of 13 + sizes were Female (92%)
Femur Size Total Male Female 1 - 2 8 2+ 5 3 18 17 3+ 7 4 6 10 59 TOTAL 18 TOTAL 41 TOTAL 13 of 59 Knees were + sizes (22%) 12 of 13 + sizes were Female (92%)
8
HIGH FLEX DESIGN - Geometry allows up to 155 degrees of flexion - Larger posterior condyle maintains low contact stress - Design allows knee to rest in posterior third of tibia
9
PATIENTS SUBCONSCIOUSLY RECOGNIZE THESE LIMITS FROM DESIGNS
Preferred Range called comfort range = stability Semi Comfort Range= muscular effort stability- positional Extreme Range= avoidance unstable activities- check reins Most important stability is mid-stance or navigating stairs. Mid-stance is a function of design of the prosthesis.
10
Femoral Components Plus Sizes If Size 4 is too wide, Downsize to 3+
Same bone cuts Narrower Thinner Flange 3+ Uses Size 3 insert Same logic for Size 3 and 2 +
11
Femoral Components Patella track is 6º 3 Radii rollback
Heel strike to toe off Flexion (up to 120º) Deep Flex (up to 145º) 4º anterior flange Posterior referencing Constant posts Constant posterior chamfer
12
CONDULAR CONTACT - Rounded femoral condyle accommodates varus-valgus lift found in eccentric loading. - Matched congruent tibial topography accommodates knee kinematics with low contact stresses. - Single Radius allows increased contact area and consistent stability w/o post and cam.
13
No Anterior Notch Resection
14
Patella 30 mm spherical dome Three pegs 29, 32, 35, 38 mm Ø
8 mm and 10 mm thick
15
MECHANICS OF PATELLA FUNCTION
16
PATELLA FLANGE - Flange is very generous but thin for patella tracking
- Designed with deep and wide groove set at 6 degrees - Because of rollback- > quad lever arm increased and improved for leverage in flexion where > stress.
17
PATELLA FEATURES AND BENEFITS
- Congruent contact reduces poly contact stress - Reduction of wear due to patella femoral groove - Improved mechanics due to wide patella flange - Improved mechanics due to decrease in quad lever arm - Design of Apex allows rollout of femur to engage patella in deeper flexion
18
SUPERIOR PATELLA TRACKING
19
Patella Tracking Motion Analysis
20
Tibial Components Two designs will eventually be offered
“Conventional” UHMWPE insert (available) “Metal on Metal” orientable insert (in development) Common philosophy Asymmetric, keeled CoCr tray Symmetric inserts Inserts matched to femurs for optimized contact stress
21
Tray (Common Features)
Size M/L A/P (Med) A/P (Lat) 1 62 41 40 2 66 44 42 3 70 46 4 75 50 47 5 80 53 6 85 56 Seven sizes Asymmetric about sagittal plane 1 mm deep pocket Grit blast CoCr alloy on inferior surfaces
22
Tray (Common Features)
Tapered post located approximately 60% A/P (closer to anterior edge) Two posteriorly swept keels Keel dimensions are shared by the size 2/3, 4/5, and 6/7 trays. Post length increases with size (40mm, 45 mm, 54 mm) 4º posterior slope
23
ASYMMETRIC BASEPLATE - Replicates the resected anatomical shape of tibia. - Maximizes coverage without overhang common in symmetrical designs. - Baseplate accepts all sizes of tibia inserts because of dovetail groove.
24
WINGED KEEL GEOMETRY - 4 Degree slope to avoid anterior tibial contact. - Swept rounded keel for stability and non contact with endosteal cortex. - Resist rotational forces due to posterior inclination of keel.
25
4 DEGREE POSTERIOR SLOPE
26
DOVETAIL TRAYS Two rails constrain the insert
Locking peg prevents A/P motion Any insert fits on any tray Slide loading for ease of assembly Taper lock peg resists backing out
27
Dovetail inserts All rails are the same width and distance
Central locking peg is tapered for locking and to contain the UHMWPE
28
Inserts (Common Features)
Standard and “Ultra” configurations 10, 12, 14, 16, 18, 20mm thickness Inserts match femoral component EtO Sterilization X-link Poly 2010
29
Optimized Contact Stress
Peak 13.4 MPa Peak 12.5 MPa Contact stresses on the Apex Modular CR (left) and Ultra (right) inserts, 0° flexion.
30
CONTACT STRESSES Yield stress for UHMWPE = 22.5 Mpa
31
Revision Tibial Components/Femoral Components
FUTURE DEVELOPMENTS Revision Tibial Components/Femoral Components
32
MOM TKA Variable Rotation and Mobile Bearing
FUTURE DEVELOPMENTS MOM TKA Variable Rotation and Mobile Bearing
33
MOM Inserts (In Development)
Factory assembled poly/metal sandwich Cryogenic assembly Highly polished inferior surface Fixed or rotating application
34
MOM Trays Rotate insert on tray to proper alignment
Lock in position using press fit peg ± 5 degrees on same size tray Future rotating platform
Similar presentations
© 2025 SlidePlayer.com. Inc.
All rights reserved.