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Restoring soft tissue function & native anatomy within tested boundaries
Total Knee Arthroplasty (TKA) is a clinically successful and effective procedure with patients typically experiencing meaningful improvements in function and pain relief. Mechanical Alignment (MA) has been the gold standard up to now.[1]MA aims to position both femoral and tibial components perpendicular to themechanicalaxis of each bone. This allows to obtain a hip-knee-ankle (HKA) angle of the limb of 180° considered as neutral under static weightbearing conditions.[2]Current situationThe challenge is that not every knee is the same2 | Patient specic alignment
Patient specic alignment | 3Whilst MA has been seen to generate excellent Clinical Outcomes [1, 2] 20%of TKA patients are unhappy with MA[4, 5]54%of MA TKA patients have residual symptoms such as pain, swelling and grinding[4]Current situationMA is not widely representative of human anatomyA study of 4,884 knee CT scans were analysed from a database of patients undergoing TKA.As shown in the chart below, the study identied the following: [3] - 4% had a neutral tibial mechanical axis - 5% had a neutral femoral mechanical axis - Only 0.1% had both at neutral tibial and femoral mechanical axis0-15 15ValgusVarus9%8%7%6%5%4%3%2%1%0%MPTALDFAUp to
- Resections are made perpendicular to Mechanical Axis- ‘Wedge’ shape / unequal resections are made- This results in straightening of the leg thus changing the leg alignment for the majority of patientsCurrent situationMechanical Alignment alters native leg alignment4 | Patient specic alignment
Current situationAltering native leg alignment results inPatient specic alignment | 5Control KA MA0-1-2-3-4-51234567891011120 10 20 30 40 50 60 70 80 90 100Adduction + ()Gait cycle (%)Fig 1. Correlation between Tibio-Femoral angle and Polyethylene thicknessChanges to JL orientation and height[5]MA results in changing the native Tibial and Femoral joint line angle (3.3° and 3.2°, respectively) and height for most patients.Less natural kinematics[6] MA showed signicant differences in kinematic parameters compared to the native knee, including ROM and Abduction-Adduction (Fig 1)Greater soft tissue imbalance[5]A study comparing MA to a restricted KA approach, showed signicantly greater frequency of imbalance (%) and larger gap (mm) in extension space for MA compared to rKA (P<0.001)DELTA in MM MA rKA0-2 68% 92%3-5 22% 7%>5 11% 2%6mmUnwornWornResection9mm9mm2mmMMLLJL ChangeResectionTibial JL (diseased)
Patient Specic Alignment (PSA) is a surgical philosophy that aims to restore soft tissue function and native anatomy, within tested & validated boundaries, utilizing a wide range of technologies. A combination of the ATTUNE® Knee prosthesis and PSA target restoration of native kinematics and may ultimately aim to improve functional outcomes and PROMS when compared to Mechanically Aligned TKAs.Patient specic alignment“ Restoration of soft tissue function and native anatomy, within tested boundaries.”6 | Patient specic alignment
In order to determine the efcacy of PSA, the necessary testing was completed to ensure implant survivorship is not compromised whilst aiming to improve patient outcomes, below are some examples of the extensive tests carried outTest conditions – PSA vs. MA, with boundary parameters of 3º HKA and 5º tibial varusTesting and validationPatient specic alignment | 71. Insert Wear[8] Result: No deleterious impact of PSA on ATTUNE® Knee in vitro wear rates 2. Tibial Fixation[9] Result: No statistical difference in xation3. Patello-femoral kinematics[10] Result: PSA was better than, or equal to MA for creep, lateral patella ligament length and Bi-facet contact4. ATTUNE® PS Implant Testing[11] Result: No impact of alignment on post / cam engagement or V/V constraintMA AAMA FB CR: 3.91±0.6AA FB CR: 2.46±2.13AA FB PS: 1.15±1.13-101234567Wear rate (mg/Mcycles200022502500275030003250350037504000Pull-off force (N)AlignmentPSA shown at 30°MA shown at 30°+0.000e+00+1.667e+00+3.333e+00+5.000e+00+6.667e+00+8.333e+00+1.000e+00+1.167e+00+1.333e+00+1.500e+00+1.667e+00+1.833e+00+2.000e+00S. Mises (Avg: 100%)
PSA is deliberately executed within Joint Line and HKA boundaries (+/-3º JL &+/-3º HKA) due to several factors:8 | Patient specic alignmentBoundaries3. Some anatomies may be biomechanically inferior and so not suitable for Alternative Alignment TKA[14,20]Fig 2. Correlation between TF angle and PE thicknessTibiofemoral angle (°}Difference in thickness (mm)-0.5°-1.0°-3.0°-3.5°-4.0°0.5°-15 -10 -5 5 102. Greater Tibio-Femoral angles are seen to result in higher PE wear and increased revision rate[13,19] 1. Increased deviations from neutral result in increased medial load [12,18] 1° varus from neutral alignment increased the medial load share by 5%Fig 1. Correlation between angular deviation and medial forceAngular deviation (°}Medial force % (Fmed/-Fz(%)1009080706050400-5 -4 -3 -2 -1 0 1 2 3 4 51st Maximum 2nd MaximumValgus VarusUnder correctionR2 = 0.75R2 = 0.87Varus Valgus
Patient specic alignment | 9Fig 2. Natural Knee Motion [16]Fig 3. Average kinematic pattern in patients treated with TKA using the ATTUNE® CR Knee.[16] -5°0°10°20°30°70°,80°120°140°130°120°110°100°90°80°10°,60°0°50-5-10-15-20Fig 4. Average AP displacement in patients treated with TKR using the ATTUNE® CR Knee [18]0° 50° 100°Med. CondyleLat. CondylemmATTUNE® Knee displays natural kinematic motionThe native knee is seen to be stable medially, and roll back laterally, however free to move posteriorly on the medial side in high exion (Fig2) [15]Multiple in vivo studies have demonstrated ATTUNE® Knee to exhibit similar medial stability to native knee, also allowing the freedom to roll back in high exion [16]A study looking at in vivo kinematic performance of ATTUNE® Knee vs. a Multi Radius design showed:- Signicantly higher lateral rollback though the ROM [6]- The kinematic pattern in AP shift was a medial pivot pattern in the ATTUNE® CR Knee group (Fig 3) [16]- Compared with the medial condyle of the femur, the lateral condyle signicantly moved posteriorly (Fig 4). [18]
Dossett et al observed:2 year Randomised Control Trial [17] demonstrated:- Oxford – 6.2 point improvement over MA (p=0.005)- WOMAC – 11 point improvement over MA (p=0.005)- ROM – average exion of 212° v. 113° (p=.002)Blakeney et al observed:- > 1 year RCT comparing 18 rKA to 18 MA TKA demonstrated: [6]- KOOS+13.5 point improvement (p=0.034)KA MA P-ValueKOOS 74 61 0.034Alternative alignment: Improved performanceStudies have shown that a PSA style technique improves PROMS scoringStudies have indicated that a PSA style technique have equivalent survivorship of 97.5% at 10 years. [19]10 | Patient specic alignment
Surgeon choicePSA can be delivered with a range of technologies, including Intuition instruments, PSI blocks, Computer Assisted Navigation and VELYSTM Robotic Assisted Solution. Therefore, providing a cost-effective solution for various hospital requirements COMPUTER ASSISTEDPatient specic alignment | 11
References:[1] Brenkel, I. (et al). Ten-year results of the Press Fit Condylar Sigma total knee replacement. 2013. Bone Joint J. 95-B(2): 177-180 [2] Insall J. (et al) (1979) The total condylar knee prosthesis. A report of two hundred and twenty cases. J Bone Joint Surg Am 61, 173–180 [3] Abdulaziz M. Almaawi, MD, MSc, Jonathan R.B. Hutt, MA, Vincent Masse, MD, Martin Lavigne, MD,Pascal-Andre Vendittoli, MD. (2017) The Impact of Mechanical and Restricted Kinematic Alignment on Knee Anatomy in Total Knee Arthroplasty. The Journal of Arthroplasty 32 (2017) 2133e2140 [4] WillemA.M.vanLieshout, et al. The negative effect ofjoint line elevation aftertotal knee arthroplasty onoutcome: Knee Surgery, Sports Traumatology, Arthroscopy (2019) 27:1477–1486 [5] W. Blakeney, J. Clement, F. Desmeules, N. Hagemeister, C. Riviere, P. Vendittoli. Kinematic alignment in total knee arthroplasty better reproduces normal gait than mechanical alignment. Knee Surg Sports Traumatol Arthrosc.2019 May;27(5):1410-1417 [6] Gunarante R, Et Al (2017) Patient dissatisfaction following total knee arthroplasty: a systematic review of the literature. J Arthoplastty 32:3854-3860 [7] Nam D (ET AL) (2014) Patient dissatisfaction following total knee replacement: a growing concern? Bone Joint J-B 96:96-10 [8] Cracaoanu, et al. ‘In vitro’ wear testing for Mechanical and Anatomic Alignments in TKA: (2019) ORS [9] Rullkoetter, et al. Impact of surgical alignment, tray material, PCL condition, and patient anatomy on proximal tibial strains after TKA.ISTA 2019 [10] Aram L. Evaluation of the Patella: Contact Pressure and Bi-facet Contact for the Attune Implant in Anatomic Alignment.DePuy Synthes Engineering Study 103573761. 2019. [11] Attune Anatomic Alignment PS Vivo Knee Simulator Wear Test: (2017) Report 103399361 [12] Halder, A., et al, “Inuence of Limb Alignment on Mediolateral Loading in Total Knee Replacement: In Vivo Measurements in Five Patients.” J Bone Joint Surg Am 94, no. 11 (2012): 1023-9. [13] A. Cerquiglini, et al. Computed Tomography Techniques Help Understand Wear Patterns in Retrieved Total Knee Arthroplasty. Journal of Arthroplasty 2018 Sep;33(9):3030-3037 [14] M. T. Hirschmann, · R. Becker · R. Tandogan, P Vendittoli, S. Howell. Alignment in TKA: what has been clear is not anymore! Knee Surgery, Sports Traumatology, Arthroscopy (2019) 27:2037–2039 [15] P. Johala, (et al) Tibio-femoral movement in the living knee. A study of weight bearing and non-weight bearing knee kinematics using ‘interventional’ MRI. J Biomech.2005 Feb;38(2):269-76 [16] Adrija Sharma (et al) In Vivo Kinematic Performance of Gradually Variable Radius PS Primary TKA J Arthroplasty.2020 Apr;35(4):1101-1108 [17] Adrija Sharma , Thomas K. Fehring , William L. Grifn , J. Bohannon Mason. In Vivo Kinematic Performance of Gradually Variable Radius PS Primary TKA J Arthroplasty.2020 Apr;35(4):1101-1108. [18] H. Takagi S Asai. (et al) Case series report of navigation-based in vivo knee kinematics in total knee arthroplasty with a gradually reducing femoral radius design. Ann Med Surg (Lond). 2017 May; 17: 33–37 [19] Dossett et al. Is the Function of Kinematically Aligned TKA Better Than Mechanically Aligned TKA? Results of a Two-Year Randomized Control Trial. Bone Joint J.2014 Jul;96-B(7):907-13 [20] W. Blakeney, J. Clement, F. Desmeules, N. Hagemeister, C. Riviere, P. Vendittoli. Kinematic alignment in total knee arthroplasty better reproduces normal gait than mechanical alignment. Knee Surg Sports Traumatol [21] Howell (et al): Implant Survival and Function Ten Years After Kinematically Aligned Total Knee Arthroplasty: (2018) Primary ArthroplastyA combination of ATTUNE® and PSA permits the restoration of soft tissue function, native anatomy and natural kinematics.©DePuy Synthes 2021. All rights reserved 169902-210309 DSUS/EMEA Please refer to the instructions for use for a complete list of indications, contraindications, warnings and precautions.