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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
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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
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
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 %) INNEX-Knee
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 (200 pts) Pre op : 116 ± 27(50-173) Post op : 184 ± 24(87-200) Bad : 1 Correct : 7 % Good : 20 % Excellent : 73 % Functional results n = 30 cases (1 year)
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 Follow-up : 1 year n = 34 112°± 18° • 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 %
Anatomical results HKA= mechanical axis postop preop H Varus HKA = 179° ± 2° (173° - 186°) 178 to 182° : 88 % Varus knees (n = 60) HKA = 172° ± 5° (160° - 180°) K A
Anatomical results postop preop H varus HKA = 179° ± 2° (173° - 186°) Valgus HKA = 180° ± 3° (178° - 184°) Varus knees (n = 60) HKA = 172° ± 5° (160° - 180°) Valgus knees (n = 13) HKA = 184° ± 3° (181° - 189°) K A
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
Distal fémoral cut F angle : 90° ± 1° • 87° : 1 • 88° : 8 • 89° : 10 • 90° : 27 • 91° : 10 • 92° : 11 • 93° : 4 n = 71 F
Distal femoral cut F angle : 90° ± 1° • 87° : 1 • 88° : 8 • 89° : 10 • 90° : 27 • 91° : 10 • 92° : 11 • 93° : 4 n = 71 93% F
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 • 90° : 25 • 91° : 7 • 92° : 3 • 93° : 3 n = 71
Tibial cut T angle : 89° ± 2° • 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
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
Patella • 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 Test used for PCL rupture : Lateral view with harmstrings contracted Flexion : 70° Posterior drawer 7.3 ± 4.7mm(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
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)
Flexion 30° in standing position n = 21 The MB is situated post to metal : 2.7± 2.4 mm 17 cases : behind (4 mm) 4 cases : before (3 mm)
Flexion 50° in standing position n = 9 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 StudyINNEX CR & INNEX UCORE. Berthonnaud, J. DimnetLaboratoire de Biomécanique du mouvementCentre Hospitalier Lyon-Sud
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
1 an Tiroir antérieur et pente tibiale favorisant la bascule