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