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3D Knee3D Knee™™ Longevity & WearLongevity & Wear
Why Knees Fail?Why Knees Fail?• 212 consecutive revised TKA, 1997-
2000Sharkey et al., CORR, 404, 2002
Key Observations
• Contact area for many TKR designs decreases with increased flexion >20°– Bourne, Clin Orthop 2003
• Small areas and high contact stress increases potential for PE wear and delamination
in vivo 6.6 years
Retrieved LCS (Harman, ISTA 2003)
3D Knee™ Articular 3D Knee™ Articular DesignDesign
• Fully congruent lateral compartment
• Widened medial condyle
• Constant sagittal profile > 70° flexion
3D Knee™ Contact Area and 3D Knee™ Contact Area and Stress Evaluated Using Finite Stress Evaluated Using Finite Element ModelsElement Models
• “Activity Model” of Gait, Stair, Squat – Morra & Greenwald, ORL, Cleveland OH– 2.5 – 4.5 BW loads– Flexion angles 0° - 135°– Non-linear UHMWPe material properties– Measured actual
manufactured implants
Competitive data from: Morra, Harman, Greenwald: Computational models can predict polymer insert damage in total knee replacements. Surgery of the Knee 4th Edition (Eds. Insall & Scott), 1(13):271-83, 2006
Contact Area and Stress at Heel Contact Area and Stress at Heel StrikeStrike
3D Knee™ vs. Fixed Bearing TKR DesignsContact Area
0 100 200 300 400
Duracon
PFC SigmaCurve
GenesisIICR
NKII Ultra
3D Knee
Contact Area (mm2)
Contact Stress
0 10 20 30 40
Duracon
PFC SigmaCurve
GenesisII CR
NKII Ultra
3D Knee
Contact Stress (MPa)
Stress Range
Competitive data from: Morra, Greenwald: Polymer insert stress in TKR designs during high flexion activities. AAOS 2005
Contact Area during High Flexion Contact Area during High Flexion ActivitiesActivities
3D Knee™ vs. “High Flexion” TKR Designs
Contact stresses < 20 MPa during stair climbing
0 100 200 300 400 500
Legacy LPS-Flex Fixed
PFC SigmaRPF
3D Knee
Contact Area (mm2)
Squat (135)Chair (90)Stair (60)
Includes Includes post/cam post/cam
contact areacontact area3D KneeTM has 32% - 61% greater contact area
during stair climbing compared to other “high flexion” designs
3DKneeTM Wear Test• Industry Contract Between
DJO Surgical and Clemson University
• Clemson UniversityBioTribology Laboratory
• Testing occurred between June - December 2007
III: 3DKneeTM Wear Test
Dynamic Wear Test Dynamic Wear Test DataData
• Instron/Stanmore 4-station force-controlled knee simulator
• 25% bovine serum at 37°C
• 5 million cycle tests
Avg. weight loss Avg. weight loss was less than was less than other designsother designs
Results: TKR Kinematics
III: 3DKneeTM Wear Test
• Lateral Pivoting Observed During Walking
PLAY VIDEOSimulator Video 2
Highly Cross-linked vs. Non-cross-
linked
IV: Comparisons to the Literature
GUR 4150100% BS
GUR 105050% BSGUR 4150?% BS
GUR 102050% BS
DJO Surgical 3DKneeTM
3D Knee™ – Retrieval 3D Knee™ – Retrieval AnalysisAnalysis
• 100 knees @ 2-5 year follow-up• 4 retrieved UHMWPe inserts
– 1 Male, 3 Female– Age at Index: 58-72– BMI: 27-33
• Reasons for Revision– Infection (2) at 11 and 13 mos.– Hemarthrosis (1) at 7 mos.– Diabetic capsulitis (1) at 6 mos.
11 Mon.
L M
6 Mon.
L M
7 Mon.
L M
13 Mon.
L M
UHMWPe Articular Damage UHMWPe Articular Damage PatternPattern
Dominant wear
mode is
burnishing, with
some scratching &
pitting
Damage consistent
with observations
from other designs
with short
functional duration Scratches
Burnish
Pits Creep
StriationsDelamination
Emb. DebrisAbrasion
Indistinguishable
Conclusions
• Wear Testing Simulators at Clemson University Performed To ISO Force-Control Standards
• 3DKneeTM system exhibited very low wear rate
• 3DKneeTM simulation confirms lateral pivot design
• 3DKneeTM outperforms a majority of published competition
V: Conclusions
Analysis of 3D Knee™ Results: Analysis of 3D Knee™ Results: Clinical Outcomes at 5 YearsClinical Outcomes at 5 Years
WA Hodge1,2,3, MK Harman2, A. Mori2, SA Banks2,3,4 1Hodge BioMotion Orthopaedics, Good Samaritan Medical Center, West Palm Beach, FL,
USA 2Institute for Mobility & Longevity, West Palm Beach, FL, USA
3Dept. of Mechanical & Aero Engineering, Univ. of Florida, Gainesville, FL, USA4Dept. of Orthopaedics & Rehabilitation, Univ. of Florida, Gainesville, FL, USA
Research grants have been received in support of these studies. One or more authors are paid consultants and/or receive royalties from DJO Surgical (Encore Medical).
509 knees509 knees• Nov 2001-Aug 2008 Nov 2001-Aug 2008 • 235 males, 274 females235 males, 274 females• Age: 73Age: 73++9 (30-93) yrs9 (30-93) yrs• Weight: 83+18 (50-159) Weight: 83+18 (50-159) kgkg• BMI: 28BMI: 28++5 (19-55)5 (19-55)
5 Year Clinical Outcomes of5 Year Clinical Outcomes of
“ACL substituting” TKR Design “ACL substituting” TKR Design
using Standard Approachusing Standard Approach
• 100 knees in 88 patients 100 knees in 88 patients – Avg. follow-up: 4.2 (3-6) yearsAvg. follow-up: 4.2 (3-6) years– surgery Nov. 2001 – Aug. 2004surgery Nov. 2001 – Aug. 2004– 45 males, 55 females45 males, 55 females– Age: 73Age: 73++8 (43-88) years8 (43-88) years– Weight: 81Weight: 81++16 (51-121) kg16 (51-121) kg– BMI: 28BMI: 28++5 (20-40)5 (20-40)– DiagnosisDiagnosis
• OA - 90 kneesOA - 90 knees• RA - 10 kneesRA - 10 knees
Initial 100 “ACL substituting” TKR Initial 100 “ACL substituting” TKR with Average 4 Year Follow Upwith Average 4 Year Follow Up
• Knee Society Score Knee Society Score (pain, function)(pain, function)
• Range of motionRange of motion
• ““Digital Goniometer” tool Digital Goniometer” tool for computerized measurement for computerized measurement of digital radiographsof digital radiographs
Outcome MeasuresOutcome Measures
JR090 at 2 yrs.
Knee Society Scores (Pain/Motion)Knee Society Scores (Pain/Motion)
Pre-OpPre-Op4747++1111
3 mos3 mos9292++1111
1 year1 year9696++77
2 year2 year9898++44
00
2020
4040
6060
8080
100100
Mean Knee Society Score (Pain/Motion)Mean Knee Society Score (Pain/Motion)
5 years5 years9797++55
3 year3 year9797++77
Knee Society Scores (Function)Knee Society Scores (Function)
Pre-OpPre-Op5151++1212
3 mos3 mos8585++2020
1 year1 year9595++1111
2 year2 year9595++1010
00
2020
4040
6060
8080
100100
Mean Knee Society Score (Function)Mean Knee Society Score (Function)
5 years5 years9595++12123 year3 year
9797++77
Passive FlexionPassive Flexion
Pre-OpPre-Op107107++88
3 mos3 mos113113++1212
1 year1 year119119++1010
2 year2 year121121++1010
8080
9090
100100
110110
120120
130130
Mean Passive Flexion (deg)Mean Passive Flexion (deg)
5 years5 years
121121++10103 year3 year
121121++1010
At last follow-up, At last follow-up, 68% have 68% have >> 120 120°° of flexion of flexion
Radiographic ResultsRadiographic Results
TKR radiolucent linesTKR radiolucent lines• 4 TKR exhibited “wide” RLL at 5 4 TKR exhibited “wide” RLL at 5
yearsyears
• All showed no progression from All showed no progression from 3 years3 years
• 3 patients had clinically 3 patients had clinically recurrent effusionsrecurrent effusions
Pre-Op (3:1 varus : Pre-Op (3:1 varus : valgus)valgus)• Varus 183° (176°-196°)Varus 183° (176°-196°)
• Valgus 170° (156°-175°)Valgus 170° (156°-175°)
• Limb correction = 6° (0°-15°)Limb correction = 6° (0°-15°)
Post-op Alignment @ Post-op Alignment @ avg. 4 yrs.avg. 4 yrs.• AP Limb = 176°AP Limb = 176°++3° valgus3° valgus
• Tibial Slope = 5°Tibial Slope = 5°++4°4°
• Patellar Tilt = 3°Patellar Tilt = 3°++3°3°
Thank You
West Palm Beach, Florida USA