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

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

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

INNEX-Knee The 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

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

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°

INNEX-Knee PCL preservation : 42 Postero-stabilisation : 12 UCOR : 19 PCL normal : 73 (100 %) ACL normal : 45 (61.5 %) ACL ruptured : 28 (38.5 %)

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.

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 : 7 % Good : 20 % Excellent : 73 %

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

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

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 %

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

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

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

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

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

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

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

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%

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

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

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

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

In conclusion, the precision of the cut is satisfactory All the cases are included (learning curve) Other TKAs INNEX-knee N = 73 90°±1 88°±2 89°±2 87°±2 no difference between Innex and other types of TKR in our experience

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

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

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

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

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

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, 42-47.

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

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

UCOR Post drawer Ant drawer n = 14 n = 10 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

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)

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)

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

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

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

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

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

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.

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

Tiroir antérieur et pente tibiale favorisant la bascule