iAssist versus conventional total knee arthroplasty in patients with varus and valgus deformities

Senthur Rajendren Vanniar, Li Ming Wang, Qing Qiang Yao, Taraka Venkata Pavan Maddali


Background: Accelerometer and gyroscope based iAssist system's accuracy in restoring the hip knee angle (HKA) in valgus and varus deformity patients is compared to that of conventional system.

Methods: In this retrospective study we compared the HKA of 26 patients in iAssist group with that of 26 patients in conventional group. The knee joints were evaluated with full leg length radiographs.

Results: The iAssist group patients’ post-operative hip knee angle was much near to our target angle when compared to that of patients in conventional technique group.

Conclusions: iAssist brings the high accuracy associated with large console CAS systems with lower costs and helps surgeons in low volume hospitals achieve specific intra operative goals with the familiarity of conventional guides.


iAssist, Navigated TKA, Varus and valgus deformity, Conventional TKA

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Kurtz S, Ong K, Lau E, Mowat F, Halpern M. Projections of primary and revision hip and knee arthroplastyin the United States from 2005 to 2030. J Bone Joint Surg Am. 2007;89:780.

Scuderi GR. Total knee arthroplasty performed with inertial navigation within the surgical field. Seminars Arthroplasty. 2014;25:179-86.

Jeffery RS, Morris RW, Denham RA. Coronal alignment aftertotal knee replacement. J Bone Joint Surgery Br. 1991;73:709–14.

Iorio R, Mazza D, Drogo P, Bolle G, Conteduca F, Redler A, et al. Clinical and radiographic outcomes of an accelerometer-based system for the tibial resection in total knee arthroplasty. Int Orthop (SICOT). 2015;39:461–6.

Goh GSH, Liow MH, Lim WSR, Tay, DKJ, Yeo SJ, Tan MH. Accelerometer-Based Navigation Is as Accurate as Optical Computer Navigation in Restoring the Joint Line and Mechanical Axis After Total Knee Arthroplasty. J Arthroplasty, 2016;31:92–7.

Thiengwittayaporn S, Fusakul Y, Kangkano N, Jarupongprapa C, Charoenphandhu N. Hand-held navigation may improve accuracy in minimally invasive total knee arthroplasty: a prospective randomized controlled trial. Int Orthop. 2016;40:51–57.

Ritter MA, Davis KE, Meding JB. The effect of alignment and BMI on failure of total knee replacement. J Bone Joint Surg Am. 2001;93(17):1588–96.

Berend ME, Ritter MA, Meding JB. Tibial component failure mechanisms in total knee arthroplasty. Clinical Orthop Rel Res. 2004;498:26–34.

Nam D, Cody EA, Nguyen JT, Figgie MP, Mayman DJ. Extramedullary Guides Versus Portable, Accelerometer-Based Navigation for Tibial Alignment in Total Knee Arthroplasty: A Randomized, Controlled Trial: Winner of the 2013 HAP PAUL Award. J Arthroplasty. 2014;29:288–94.

Anderson KC, Buehler KC, Markel DC. Computer assisted navigation in total knee arthroplasty: comparison with conventional methods. J Arthroplasty. 2005;20(7):132.

Gharaibeh MA, Solayar GN, Harris IA, Chen DB, Samuel J. MacDessi SJ. Accerelator-based, portable navigation (KneeAlign) Vs conventional instrumentation for total knee arthroplasty: A prospective randomized comparative trial. J Arthroplasty. 2017;32(3):777-82.

Anderson KC, Buehler KC, Markel DC. Computer assisted navigation in total knee arthroplasty: comparison with conventional methods. J Arthroplasty. 2005;20:132–8.

Mason JB, Fehring TK, Estok R, Banel D, Fahrbach K. Meta-analysis of alignment outcomes in computer-assisted total knee arthroplasty surgery. J Arthroplasty. 2007;22:1097–106.

Bathis H, Perlick L, Tingart M. Alignment in total knee arthroplasty. A comparison of computer assisted surgery with conventional technique. J Bone Joint Surg Br. 2004;86B:682–7.

Mahaluxmivala J, Bankes MJ, Nicolai P. The effect surgeon experience on component positioning in 673 press fit condylar posterior cruciate-sacrificing total knee arthroplasties. J Arthroplasty. 2001;16:635.

Blakeney WG, Khan RJ, Wall SJ. Computer-assisted techniques versus conventional guides for component alignment in total knee arthroplasty: a randomized controlled trial. J Bone Joint Surg Br. 2011;93:1377–84.

Barrett WP, Mason JB, Moskal JT, Dalury DF, Oliashirazi A, Fisher DA. Comparison of radiographic alignment of imageless computer-assisted surgery vs conventional instrumentation in primary total knee arthroplasty. J Arthroplasty. 2011;26:1273–84.

Hoke D, Jefari M, OrozcoF, Ong A. Tibial shaft stress fractures resulting from placement of navigation tracker pins. J Arthroplasty. 2011;26(3):504.

Fujimoto E, Sasashige Y, Nakata K, Yokota G, Omoto T, Ochi M. Technical Considerations and Accuracy Improvement of Accelerometer-Based Portable Computer Navigation for Performing Distal Femoral Resection in Total Knee Arthroplasty. J Arthroplasty. 2017;32:53-60.

Scuderi GR, Fallaha M, Masse V. Total knee arthroplasty with a novel navigation system within the surgical field. Orthop Clin North Am. 2014;45(2):167.

Available at: ortho/rotational alignment of femoral app cutting guide. Accessed on 3 October 2017.

Abdel MP, Oussedik S, Parratte S, Lustig S, Haddad FS. Coronal alignment in total knee replacement: historical review, contemporary analysis, and future direction. J Bone Joint Surg. 2014;96:857-62.

Rand JA, Coventry MB. Ten-year evaluation of geometric total knee arthroplasty. Clin Orthop Related Res. 1988;232:168.

Parratte S, Pagnano MW, Trousdale RT. Effect of postoperative mechanical axis alignment on the fifteen-year survival of modern, cemented total knee replacements. J Bone Joint Surg Am. 2010;92:2143.

Desseaux A, Graf P, Dubrana F, Marino R, Clave A. Radiographic outcomes in the coronal plane with iASSITTM versus optical navigation for total knee arthroplasty: A preliminary case-control study. Orthop Traumatol Surg Res. 2016;102:363-8.

Pickering S, Armstrong D. Focus On Alignment in Total Knee Replacement. J Bone Joint Surg. 2012;1:3.

Nam D, Cody EA, Nguyen JT, Figgie MP, Mayman DJ. Extramedullary guides versus portable, accelerometer-based navigation for tibial alignment in total knee arthroplasty: a randomized, controlled trial. J Arthroplasty. 2014;29:288-94.

Owens Jr RF, Swank ML. Low incidence of postoperative complications due to pin placement in computer-navigated total knee arthroplasty. J Arthroplasty. 2010;25(7):1096-8.

Confalonieri N, Chemello C, Cerveri P. Is computer assisted total knee replacement for beginners or experts? Prospective study among three groups of patients treated by surgeons with different levels of experience. J Orthop Traumatol. 2012;13:203-10.