1. INNEX-Knee The Lyon experience
J.L Lerat, B. Moyen, I. Bénareau
E. Berthonnaud, J. Dimnet
Service de Chirurgie Orthopédique &
Laboratoire de Biomécanique du Mouvement
Centre Hospitalier Lyon-Sud

2. INNEX-Knee The Lyon experience
J.L Lerat, B. Moyen, I. Bénareau
E. Berthonnaud, J. Dimnet
Service de Chirurgie Orthopédique &
Laboratoire de Biomécanique du Mouvement
Centre Hospitalier Lyon-Sud
Aim of the presentation
1 - Preliminary results (1 to 3 years)
2 - Anterior-posterior laxity
3 - Mobility of the plateau

3. INNEX-Knee The Lyon experience
1st Pilot study (April Nov. 1998)
Innex knee cemented femur and tibia :
30 cases (20 CR - 10 PS)

4. INNEX-Knee The Lyon experience
1st Pilot study (April Nov. 1998)
Innex knee cemented femur and tibia :
30 cases (20 CR - 10 PS)
2nd Pilot study (Nov ct. 2000)
Innex knee non cemented femur :
20 cases (10 CR - 10 UCOR)
+ further experience : 23 cases

5. Some cases are particularly difficult for a pilot study
INNEX-Knee
The LYON experience
73 cases
44 F - 29 M
Age : 69 ± 10 years (26-88)
Etiology
2 R. A, 1 SVNH
2 hemophilic arthropathies
1 Paget’s disease
68 gonarthrosis
- 14 previous osteotomies
- 6 previous surgery (2 ACL,1 fract, 2 patella)
Some cases are particularly difficult for a pilot study

6. INNEX-Knee These difficulties explain : Op. time : 90 mn ± 19 (55-145)
Tibial tuberosity ost : 10 cases
Immediate weight bearing
Discharge : 7 days
Flexion after 7 days : 80°

7. INNEX-Knee PCL preservation : 42 Postero-stabilisation : 12 UCOR : 19
PCL normal : (100 %)
ACL normal : (61.5 %)
ACL ruptured : 28 (38.5 %)

8. Complications 1 Reflex Sympathic Dystrophy 11 Deep Veinous Thombosis
1 fracture of tibial tubercule (fall in stairs after 1 month)
1 skin necrosis (after 8 op with 7 skin incisions : arthrodesis)
0 infection
4 Manipulations under Gen. anest.

9. Internat. Knee Society Score
Functional results
n = 30 cases (1 year)
Internat. Knee Society Score
(200 pts)
Pre op : 116 ± 27 (50-173)
Post op : 184 ± 24 (87-200)
Bad : 1
Correct : %
Good : %
Excellent : 73 %

10. Mobility After 2 months n = 66 Flexion = 106° ± 18 (45° - 140°)
Extension : 0° : 55 cas
- 5° : 6 cas
-10° : 5 cas
45-80° : 5
85°-95° : 8
100°-105° : 12
110°-115° : 14
120°-125° : 16
130°-135° : 9
135°-140° : 2

11. Mobility Follow-up : 1 year n = 34 Flexion = 112°± 18° (45° - 140°)
Extension : -1° ± 3°
0° : 29 cases
- 5° : 2 cases
-10° : 3 cases
45°-80° : 2
90°-95° : 2
100°-105° : 4
105°-110° : 6
110°-120° : 4
120°-125° : 7
125°-130° : 3
130°-140° : 6

12. Mobility 112°± 18° Follow-up : 1 year n = 34 45°-80° : 2 90°-95° : 2
100°-105° : 4
105°-110° : 6
110°-120° : 4
120°-125° : 7
125°-130° : 3
130°-140° : 6
> 120° : 47 %

14. preop postop Anatomical results H K A HKA= mechanical axis
Varus knees (n = 60)
HKA = 172° ± 5°
(160° - 180°)
Varus
HKA = 179° ± 2°
(173° - 186°)
178 to 182° : 88 % K A

15. preop postop Anatomical results H K A Varus knees (n = 60)
(160° - 180°)
Valgus knees (n = 13)
HKA = 184° ± 3°
(181° - 189°)
varus
HKA = 179° ± 2°
(173° - 186°)
Valgus
HKA = 180° ± 3°
(178° - 184°) K A

16. Precision of the cuts n=71 F (femur A-P) : 90° ± 1
T (tibia A-P) : 89° ± 2
Femur lateral : 88° ± 2
Tibia lateral : 87° ± 2
n=71

17. Distal fémoral cut F F angle : 90° ± 1° 87° : 1 88° : 8 89° : 10
87° : 1
88° : 8
89° : 10
90° : 27
91° : 10
92° : 11
93° : 4
n = 71 F

18. Distal femoral cut F F angle : 90° ± 1° 87° : 1 88° : 8 89° : 10
87° : 1
88° : 8
89° : 10
90° : 27
91° : 10
92° : 11
93° : 4
n = 71
93% F

19. Important pre operative measurement to do a precise distal cut
HKS angle : 6° ± 2
Important pre operative measurement to do a precise distal cut H
2° : 1 case
3° : 2
4° : 6
5° : 29
6° : 14
7° : 9
8° : 6
9° : 2
10° : 2
11° : 2
n = 73 S K

20. Tibial cut T angle : 89° ± 2° 85° : 1 86° : 1 87° : 9 88° : 14 89° : 8
85° : 1
86° : 1
87° : 9
88° : 14
89° : 8
90° : 25
91° : 7
92° : 3
93° : 3
n = 71

21. Tibial cut T angle : 89° ± 2° 81% 85° : 1 86° : 1 87° : 9 88° : 14
85° : 1
86° : 1
87° : 9
88° : 14
89° : 8
90° : 25
91° : 7
92° : 3
93° : 3
n = 71
81%

22. Position of the components
Inclination of femoral component : F lateral
88° ± 2°
85° : 11
86° : 7
87° : 13
88° : 8
89° : 5
90° : 24
92° : 1
n = 71

23. Sometimes, metaphyseal axis should be better
The intramedullary axis is not always the recommended guide for anterior and posterior cuts
Sometimes, metaphyseal axis should be better

24. Position of the components
Inclination of tibial component : T lateral
Instrumentation takes into account the mean anatomical slope : 6° (or 84°)
82° : 2
83° : 3
84° : 9
85° : 5
86° : 9
87° : 18
88° : 9
89° : 1
90° : 11
91° : 3
87° ± 2

25. Position of the components
Inclination of tibial component : T lateral
82° : 2
83° : 3
84° : 9
85° : 5
86° : 9
87° : 18
88° : 9
89° : 1
90° : 11
91° : 3
The difference comes probably from the fact that the measurements are done on short X-ray films and not on the complete tibia
87° ± 2

26. In conclusion, the precision of the cut is satisfactory
All the cases are included (learning curve)
Other TKAs INNEX-knee
N = 73
90°± °±2
89°± °±2
no difference between Innex and other types of TKR in our experience

27. Only 1 case of secondary patellar resurfacing
64/73 without resurfacing
Thickness of bone = 22 ± 2 mm
9 patella resurfaced
Blackburn index p. op = 0.76 ± 0.16
Patella centered : 68 cases
Subluxation (1 to 3 mm) : 5 cases
Only 1 case of secondary patellar resurfacing

28. Patella 9 patellar resurfacing (12 %) Thickness of bone = 22 ± 2 mm
Post-op thickness of bone = 14 ± 1 mm

29. Interest of the CSTI used successfully with the « Natural knee »
530 knees
follow-up max. : 4.5 Y
CSTI

30. The short stem of Innex is an advantage in TKA after osteotomy
UCOR

31. In case of severe valgus after HTO the short stem of Innex permits to associate TKR and a new osteotomy in the same time

32. Innex CR + osteotomy
Extension Post drawer Ant drawer

33. Second part Study of anterior and posterior drawer
Study of the mobility of MB
Anterior-posterior translation during flexion
Anterior-posterior translation during radiological drawer-test
Rotation

34. Radiological anterior drawer
Flexion : 20°
9 kg load
Free translation
Free rotation
« Knee instability after injury to the anterior cruciate ligament
Quantification of the Lachman test »
JL Lerat, B Moyen, F Cladière, JL Besse, H Abidi
J. Bone Joint Surgery VOL. 82-B, N°1, January 2000,

35. Radiological anterior drawer
Flexion : 20°
9 kg load
Free translation
Free rotation
Anterior drawer
6.5 ± 5.4 mm (6-16)
n = 34

36. Posterior drawer Posterior drawer 7.3 ± 4.7 mm (1-15) n = 65
Test used for PCL rupture :
Lateral view with harmstrings contracted
Flexion : 70°
Posterior drawer
7.3 ± 4.7 mm (1-15)
n = 65

37. UCOR Post drawer Ant drawer n = 14 n = 10
Post drawer : 10 mm ± Ant drawer : 4.3 mm ± 5
n = n = 10

38. Study of the mobility of mobile bearing
Anterior-posterior translation

39. Combination of translation and rotation

40. Study of the position of the Mobile plateau
In full extension in one leg standing position
At 30° of flexion in one leg standing position
AT 50-60° of flexion in one leg standing position

41. Mobility of mobile bearing
Extension in standing position
n = 40
The MB is situated post. to metal : 2.2 ± 2.4 mm
33 cases : posteriorly (3.4 mm)
7 cases : anteriorly (3.7 mm)

42. n = 21 Flexion 30° in standing position
The MB is situated post to metal : 2.7 ± 2.4 mm
17 cases : behind (4 mm)
4 cases : before (3 mm)

43. n = 9 Flexion 50° in standing position
The plateau is always situated post to metal : 4.3 ± 2.7 mm

44. Position of the mobile bearing in ant. and post. drawer
Post drawer : 7.3 ± 4.7 mm
M B situated 1.7 mm post to metal
35 cases post : 4.5 mm
18 cases ant : 2.8 mm
n = 53 cases
Ant drawer : 6.5 ± 5.4 mm
M B situated 4 mm post. to metal
3 cases ant : 2.5 mm
24 cases post : 4.4 mm
n = 24 cases

45. Total A-P translation of Mobile Bearing :
5.7 ± 3.9 mm ( ) range : 13.7 mm
Posterior drawer Anterior drawer

46. X-ray Mobility Study INNEX CR & INNEX UCOR E. Berthonnaud, J
X-ray Mobility Study INNEX CR & INNEX UCOR E. Berthonnaud, J. Dimnet Laboratoire de Biomécanique du mouvement Centre Hospitalier Lyon-Sud

47. 3 balls in the polyethylene
Study of the rotation - Preliminary results
3 balls in the polyethylene

48. Calculation of the PE mobility with one X-ray
X-ray plate
INNEX with 3 steel balls embedded in the PE .
X-ray source
Known : - Distance between X-ray source and X-ray plate. - Position of the X-ray source on the X-ray.
Known :
- The size of the INNEX (tibial base plate)
- The interdistances between balls in PE.
Measured :
The position of rotation axis
The position of the balls
The position of the tibial plots
Calculated:
- The rotation  between the PE and the tibial base plate.
- The translation t between the PE and the tibial base plate.

49. Mobility of the PE plateau vs tibial component (first results)
Total amount of rotation from full extension to 50° of flexion in standing position
10.5° 8°
4.5°
3.5° 1° 2°
3,5°
The study is just starting and should be multicentric

50. Tiroir antérieur et pente tibiale favorisant la bascule