J.L Lerat, B. Moyen, I. Bénareau

E. Berthonnaud, J. Dimnet Service de Chirurgie Orthopédique &

Laboratoire de Biomécanique du Mouvement

Centre Hospitalier Lyon-Sud

INNEX-Knee INNEX-Knee The Lyon experienceThe 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

INNEX-Knee INNEX-Knee The Lyon experienceThe Lyon experience

Aim of the presentation

1 - Preliminary results (1 to 3 years)

2 - Anterior-posterior laxity 3 - Mobility of the plateau

INNEX-KneeINNEX-KneeThe Lyon experienceThe Lyon experience

1st Pilot study (April 1998 - Nov. 1998)

• Innex knee cemented femur and tibia :

30 cases (20 CR - 10 PS)

INNEX-KneeINNEX-KneeThe Lyon experienceThe Lyon experience

1st Pilot study (April 1998 - Nov. 1998)

• Innex knee cemented femur and tibia :

30 cases (20 CR - 10 PS)

2nd Pilot study (Nov. 1999 - 0ct. 2000)

• Innex knee non cemented femur :

20 cases (10 CR - 10 UCOR)

+ further experience : 23 cases

73 cases • 44 F - 29 M• Age : 69 ± 10 years (26-88)

• Etiology2 R. A, 1 SVNH

2 hemophilic arthropathies1 Paget’s disease68 gonarthrosis

- 14 previous osteotomies - 6 previous surgery (2 ACL,1 fract, 2 patella)

INNEX-Knee INNEX-Knee The LYON experienceThe LYON experience

Some cases are particularly difficult for a pilot study

INNEX-KneeINNEX-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°

INNEX-KneeINNEX-Knee

PCL preservation : 42

Postero-stabilisation : 12

UCOR : 19

PCL normal : 73 (100 %)

ACL normal : 45 (61.5 %)

ACL ruptured : 28 (38.5 %)

ComplicationsComplications

• 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.

Functional resultsFunctional results

Internat. Knee Society Score(200 pts)

Pre op : 116 ± 27 (50-173)

Post op : 184 ± 24 (87-200)

Bad : 1 Correct : 7 % Good : 20 % Excellent : 73 %

n = 30 cases (1 year)

Flexion = 106° ± 18

(45° - 140°)

Extension : 0° : 55 cas - 5° : 6 cas -10° : 5 cas

After 2 monthsn = 66

• 45-80° : 5 • 85°-95° : 8• 100°-105° : 12• 110°-115° : 14• 120°-125° : 16• 130°-135° : 9• 135°-140° : 2

Mobility Mobility

Follow-up : 1 yearn = 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

Mobility Mobility

Flexion = 112°± 18°

(45° - 140°)

Extension : -1° ± 3°

0° : 29 cases

- 5° : 2 cases -10° : 3 cases

Follow-up : 1 yearn = 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

Mobility Mobility

112°± 18°

> 120° : 47 %

Anatomical resultsAnatomical results

Varus knees (n = 60)

HKA = 172° ± 5°

(160° - 180°)

preop

Varus

HKA = 179° ± 2°

(173° - 186°)

178 to 182° : 88 %

postopH

K

A

HKA= mechanical axis

Varus knees (n = 60)

HKA = 172° ± 5°

(160° - 180°)

Valgus knees (n = 13)

HKA = 184° ± 3°

(181° - 189°)

preop

varus

HKA = 179° ± 2°

(173° - 186°)

Valgus

HKA = 180° ± 3°

(178° - 184°)

postopH

K

A

Anatomical resultsAnatomical results

Precision of the cuts

F (femur A-P) : 90° ± 1

T (tibia A-P) : 89° ± 2

Femur lateral : 88° ± 2

Tibia lateral : 87° ± 2

n=71

F angle : 90° ± 1°

Distal fémoral cutDistal fémoral cut

• 87° : 1• 88° : 8• 89° : 10• 90° : 27• 91° : 10• 92° : 11• 93° : 4

n = 71

F

F angle : 90° ± 1°

Distal femoral cutDistal femoral cut

• 87° : 1• 88° : 8• 89° : 10• 90° : 27• 91° : 10• 92° : 11• 93° : 4

n = 71

F

93%

HKS angle : 6° ± 2

• 2° : 1 case

• 3° : 2

• 4° : 6

• 5° : 29

• 6° : 14

• 7° : 9

• 8° : 6

• 9° : 2

• 10° : 2

• 11° : 2

n = 73

H

K

S

Important pre operative measurement to do a

precise distal cut

Tibial cutTibial cut

• 85° : 1• 86° : 1• 87° : 9• 88° : 14• 89° : 8• 90° : 25• 91° : 7• 92° : 3• 93° : 3 n = 71

T angle : 89° ± 2°

Tibial cutTibial cut

• 85° : 1• 86° : 1• 87° : 9• 88° : 14• 89° : 8• 90° : 25• 91° : 7• 92° : 3• 93° : 3 n = 71

T angle : 89° ± 2°

81%

Position of the componentsPosition 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

The intramedullary axis is not always the recommended guide for anterior and posterior cuts

Sometimes, metaphyseal axis should be better

Position of the componentsPosition of the components

82° : 2

83° : 3

84° : 9

85° : 5

86° : 9

87° : 18

88° : 9

89° : 1

90° : 11

91° : 3

Inclination of tibial component : T lateral

87° ± 2

Instrumentation takes into account the mean anatomical slope : 6° (or 84°)

Position of the componentsPosition of the components

82° : 2

83° : 3

84° : 9

85° : 5

86° : 9

87° : 18

88° : 9

89° : 1

90° : 11

91° : 3

Inclination of tibial component : T lateral

87° ± 2

The difference comes probably from the fact that the measurements are done on short X-ray films and not on

the complete tibia

N = 73

90°±1 88°±2

89°±2 87°±2

Other TKAs INNEX-knee

In conclusion, the precision of the cut is satisfactory

All the cases are included (learning curve)

no difference between Innex and other types of TKR in our experience

PatellaPatella

• 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

• 9 patellar resurfacing (12 %)

• Thickness of bone = 22 ± 2 mm

• Post-op thickness of bone = 14 ± 1 mm

PatellaPatella

Interest of the CSTI used successfully with the « Natural knee »

CSTI

530 knees

follow-up max. : 4.5 Y

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

UCOR

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

Innex CR + osteotomy

Extension Post drawer Ant drawer

• 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

Second part

« 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, 42-47.

Radiological anterior drawerRadiological anterior drawer

• Flexion : 20°Flexion : 20°• 9 kg load9 kg load• Free translation Free translation • Free rotation Free rotation

Radiological anterior drawerRadiological anterior drawer

• Flexion : 20°Flexion : 20°• 9 kg load9 kg load• Free translation Free translation • Free rotation Free rotation

Anterior drawer6.5 ± 5.4 mm (6-16)

n = 34

Posterior drawer Posterior drawer

Test used for PCL rupture :Test used for PCL rupture :

Lateral view with harmstrings Lateral view with harmstrings contractedcontracted

Flexion : 70°Flexion : 70°

Posterior drawer7.3 ± 4.7 mm (1-15)

n = 65

UCOR

Post drawer Ant drawer

Post drawer : 10 mm ± 4 Ant drawer : 4.3 mm ± 5

n = 14 n = 10

Study of the mobility of mobile bearing

Anterior-posterior translation

Combination of translation and rotation

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

Extension in standing position

The MB is situated post. to metal : 2.2 ± 2.4 mm

33 cases : posteriorly (3.4 mm)

7 cases : anteriorly (3.7 mm)

n = 40

Mobility of mobile bearing

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)

n = 21

Flexion 50° in standing position

The plateau is always situated post to metal : 4.3 ± 2.7 mm

n = 9

Post drawer : 7.3 ± 4.7 mm

• M B situated 1.7 mm post to metal

35 cases post : 4.5 mm18 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 mm24 cases post : 4.4 mm

n = 24 cases

Position of the mobile bearing in ant. and post. drawer

Posterior drawer + Anterior drawer

Total A-P translation of Mobile Bearing : 5.7 ± 3.9 mm (0.5 - 14.2) range : 13.7 mm

X-ray Mobility StudyINNEX CR & INNEX UCOR

E. Berthonnaud, J. Dimnet

Laboratoire de Biomécanique du mouvementCentre Hospitalier Lyon-Sud

3 balls in the polyethylene

Study of the rotation - Preliminary results

Calculation of the PE mobility with one X-ray

X-ray plate

X-ray source

INNEX with 3 steel balls embedded in the PE

.

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.

Calculated:- The rotation between the PE and the tibial base plate.- The translation t between the PE and the tibial base plate.

Measured :

The position of rotation axis

The position of the balls

The position of the tibial plots

Mobility of the PE plateau vs tibial component(first results)

10.5°

8°

4.5°

3.5°

1°

2°

3,5°

Total amount of rotation from full extension to 50° of flexion in standing position

The study is just starting and should be multicentric

Tiroir antérieur et pente tibiale favorisant la bascule

1 an