1. PREDICTING KNEE JOINT
CONTACT PRESSURE AND
SHEAR STRESS FOR
DIFFERENT ALIGNMENTS
Reisse, F.1
; Hillstrom, H.J.2,1
; Walker, R.W.1
;
Carpanen, D.1
; Lenhoff, M.W.2
; Imhauser,
C.W.2
; Rozbruch, S.R.2
; Fragomen, A.T.;
Koff, M.F.2
; Dowell, J.3
; Mootanah, R.1,2
Franziska.reisse@anglia.ac.uk
0
1. Anglia Ruskin University, Chelmsford, Essex, UK;
2. Hospital for Special Surgery (HSS), New York, NY, USA.
3. Mid Essex Hospital Services NHS Trust

2. Background
• Current targets:
MAD = 0mm
Fujisawa point

3. Gap in knowledge
Underlying link between the MAD and knee
joint contact mechanics is not well understood

4. Aim
• Determine the relationship between
malalignment and the resulting knee joint
contact mechanics
• Stress cannot be measured in vivo and the use
of computational methods can yield useful
information about joint mechanics.

5. Model Development

6. 3D model
anterior (front) view posterior (back) view

7. Constraint Definitions
Type Constraint
Perfect bonding Cartilage - Bones
Perfect bonding Ligaments - Bones
Perfect bonding Meniscal Horns – Tibia
Cartilage-cartilage and cartilage-
meniscus interfaces were modelled as
frictionless sliding

8. Boundary Conditions
Model validation, using 6 DOF robot:
1. Fix the proximal femur
2. Apply axial load at the distal tibia
3. Set constraints:
•Flx/ext constrained in sagittal plane
• Other degrees of freedom free
4. Apply different bending moments

9. Cadaveric study to validate
finite element models
Cadaveric specimen
in 6 degree of
freedom robot

10. Validation
Axial force: 374 N
Bending moment:
15 Nm varus
Axial force: 374 N
Bending moment:
0 Nm
Axial force: 374 N
Bending moment:
15 Nm valgus
A A A
PP P
MM
M
LL L
A A A
PP P
MM M
L
L L
a) In Vitro Results
b) Finite Element Results
Pressure (MPa)

11. Validation
%FSE medial:
•6.67%
%FSE lateral:
•5.94%

12. Simulation of Gait

13. Force distribution

14. Pressure
Knock-legged
Bow-legged

15. Shear stress

16. Summary
• Minimum peak contact pressure occurred at an MAD of
-1.44 mm and a corresponding HKA angle of 0.5° valgus
• Minimum peak shear stress occurred at an MAD of 3.6 mm
and a corresponding HKA angle of 2.5° valgus

17. Discussion
• A computational model has been developed to
predict stress and force as a function of
malalignment prior to surgery
• Understanding the link between malalignment
and knee joint stress will help improve surgical
outcomes

18. Future Improvement
• Computational model generalisation,
using 10 knees – Three year Arthritis
Research UK funding

19. • This research was gratefully funded by the Chelmsford
Medical Education and Research Trust
Acknowledgements