Preliminary experience with an image-free handheld robot for total knee arthroplasty: 77 cases compared with a matched control group

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Achieving an optimal limb alignment is an important factor affecting the long-term survival of total knee arthroplasty (TKA). This is the first study to look at the limb alignment and orientation of components in TKA using a novel image-free handheld robotic sculpting system.


This case-controlled study retrospectively compared limb and component alignment of 77 TKAs performed with a robot (Robot-group) with a matched control group of patients who received conventional alignment with intramedular rods (Control group). Alignment and component positioning was measured on full-leg weight-bearing and standard lateral X-rays by two independent observers. The image-free handheld robotic sculpting system calculated the planned and achieved mechanical axis (MA). Outliers were defined as > 3° deviation from planned alignment.


Mean MA was 180.1° (SD = 1.9) in the Robot-group, compared to the Control group with a mean MA of 179.1° (SD = 3.1, p = 0.028). We observed 5 outliers (6%) in the Robot-group and 14 outliers (18%, p = 0.051) in the Control group. Fraction of outliers of the frontal tibial component was 0% in the Robot-group versus 8% in the Control group (p = 0.038). There were no other statistical differences regarding the implant positioning between both groups.


The Robot-group showed significantly less outliers compared to the conventional technique. Whether these differences are clinically relevant is questionable and should be investigated on the long term. Randomized controlled trials with larger patient series will be needed in the future to confirm our preliminary results.

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  1. 1.

    Bourne RB, Chesworth BM, Davis AM, Mahomed NN, Charron KD (2010) Patient satisfaction after total knee arthroplasty: who is satisfied and who is not? Clin Orthop Relat Res 468(1):57–63.

  2. 2.

    Gothesen O, Espehaug B, Havelin L, Petursson G, Lygre S, Ellison P, Hallan G, Furnes O (2013) Survival rates and causes of revision in cemented primary total knee replacement: a report from the Norwegian Arthroplasty Register 1994–2009. Bone Joint J.

  3. 3.

    Parratte S, Pagnano MW, Trousdale RT, Berry DJ (2010) Effect of postoperative mechanical axis alignment on the fifteen-year survival of modern, cemented total knee replacements. J Bone Joint Surg Am 92(12):2143–2149.

  4. 4.

    Lotke PA, Ecker ML (1977) Influence of positioning of prosthesis in total knee replacement. J Bone Joint Surg Am 59(1):77–79

  5. 5.

    Golladay GJ, Bradbury TL, Gordon AC, Fernandez-Madrid IJ, Krebs VE, Patel PD, Suarez JC, Higuera Rueda CA, Barsoum WK (2019) Are patients more satisfied with a balanced total knee arthroplasty? J Arthroplast 34(7s):S195–s200.

  6. 6.

    Fehring TK, Odum S, Griffin WL, Mason JB, Nadaud M (2001) Early failures in total knee arthroplasty. Clin Orthop Relat Res 392:315–318.

  7. 7.

    Ritter MA, Faris PM, Keating EM, Meding JB (1994) Postoperative alignment of total knee replacement. Its effect on survival. Clin Orthop Relat Res 299:153–156

  8. 8.

    Jeffery RS, Morris RW, Denham RA (1991) Coronal alignment after total knee replacement. J Bone Joint Surg Br 73(5):709–714

  9. 9.

    Bargren JH, Blaha JD, Freeman MA (1983) Alignment in total knee arthroplasty. Correlated biomechanical and clinical observations. Clin Orthop Relat Res 173:178–183

  10. 10.

    Mason JB, Fehring TK, Estok R, Banel D, Fahrbach K (2007) Meta-analysis of alignment outcomes in computer-assisted total knee arthroplasty surgery. J Arthroplast 22(8):1097–1106.

  11. 11.

    Hetaimish BM, Khan MM, Simunovic N, Al-Harbi HH, Bhandari M, Zalzal PK (2012) Meta-analysis of navigation vs conventional total knee arthroplasty. J Arthroplast 27(6):1177–1182.

  12. 12.

    Cheng T, Pan XY, Mao X, Zhang GY, Zhang XL (2012) Little clinical advantage of computer-assisted navigation over conventional instrumentation in primary total knee arthroplasty at early follow-up. Knee 19(4):237–245.

  13. 13.

    Gothesen O, Espehaug B, Havelin LI, Petursson G, Hallan G, Strom E, Dyrhovden G, Furnes O (2014) Functional outcome and alignment in computer-assisted and conventionally operated total knee replacements: a multicentre parallel-group randomised controlled trial. Bone Joint J.

  14. 14.

    Harvie P, Sloan K, Beaver RJ (2012) Computer navigation vs conventional total knee arthroplasty: five-year functional results of a prospective randomized trial. J Arthroplasty 27(5):667–672.e661.

  15. 15.

    Lonner JH, John TK, Conditt MA (2010) Robotic arm-assisted UKA improves tibial component alignment: a pilot study. Clin Orthop Relat Res 468(1):141–146.

  16. 16.

    Tigani D, Busacca M, Moio A, Rimondi E, Del Piccolo N, Sabbioni G (2009) Preliminary experience with electromagnetic navigation system in TKA. Knee 16(1):33–38.

  17. 17.

    (2013) World Medical Association Declaration of Helsinki. JAMA 310 (20):2191

  18. 18.

    Kazis LE, Anderson JJ, Meenan RF (1989) Effect sizes for interpreting changes in health status. Med Care 27(3 Suppl):S178–189

  19. 19.

    Insall JN, Binazzi R, Soudry M, Mestriner LA (1985) Total knee arthroplasty. Clin Orthop Relat Res 192:13–22

  20. 20.

    Longstaff LM, Sloan K, Stamp N, Scaddan M, Beaver R (2009) Good alignment after total knee arthroplasty leads to faster rehabilitation and better function. J Arthroplasty 24(4):570–578.

  21. 21.

    Abdel MP, Ollivier M, Parratte S, Trousdale RT, Berry DJ, Pagnano MW (2018) Effect of postoperative mechanical axis alignment on survival and functional outcomes of modern total knee arthroplasties with cement: a concise follow-up at 20 years. J Bone Joint Surg Am 100(6):472–478.

  22. 22.

    Bellemans J, Colyn W, Vandenneucker H, Victor J (2012) The Chitranjan Ranawat award: is neutral mechanical alignment normal for all patients? The concept of constitutional varus. Clin Orthop Relat Res 470(1):45–53.

  23. 23.

    Thienpont E, Schwab PE, Fennema P (2017) Efficacy of patient-specific instruments in total knee arthroplasty: a systematic review and meta-analysis. J Bone Joint Surg Am 99(6):521–530.

  24. 24.

    Ren Y, Cao S, Wu J, Weng X, Feng B (2019) Efficacy and reliability of active robotic-assisted total knee arthroplasty compared with conventional total knee arthroplasty: a systematic review and meta-analysis. Postgrad Med J 95(1121):125–133.

  25. 25.

    Sabharwal S, Zhao C (2008) Assessment of lower limb alignment: supine fluoroscopy compared with a standing full-length radiograph. J Bone Joint Surg Am 90(1):43–51.

  26. 26.

    Jang KM, Lee JH, Cho IY, Park BK, Han SB (2017) Intraoperative Fluoroscopic assessment of limb alignment is a reliable predictor for postoperative limb alignment in biplanar medial opening-wedge high tibial osteotomy. J Arthroplasty 32(3):756–760.

  27. 27.

    Berend ME, Ritter MA, Meding JB, Faris PM, Keating EM, Redelman R, Faris GW, Davis KE (2004) Tibial component failure mechanisms in total knee arthroplasty. Clin Orthop Relat Res 428:26–34.

  28. 28.

    Lonner JH, Smith JR, Picard F, Hamlin B, Rowe PJ, Riches PE (2015) High degree of accuracy of a novel image-free handheld robot for unicondylar knee arthroplasty in a cadaveric study. Clin Orthop Relat Res 473(1):206–212.

  29. 29.

    Smith JR, Riches PE, Rowe PJ (2014) Accuracy of a freehand sculpting tool for unicondylar knee replacement. Int J Med Robot 10(2):162–169.

  30. 30.

    Casper M, Mitra R, Khare R, Jaramaz B, Hamlin B, McGinley B, Mayman D, Headrick J, Urish K, Gittins M, Incavo S, Neginhal V (2018) Accuracy assessment of a novel image-free handheld robot for total knee arthroplasty in a cadaveric study. Comput Assist Surg (Abingdon) 23(1):14–20.

  31. 31.

    Solayar GN, Chinappa J, Harris IA, Chen DB, Macdessi SJ (2017) A comparison of plain radiography with computer tomography in determining coronal and sagittal alignments following total knee arthroplasty. Malays Orthop J 11(2):45–52.

  32. 32.

    Schmidt GL, Altman GT, Dougherty JT, DeMeo PJ (2004) Reproducibility and reliability of the anatomic axis of the lower extremity. J Knee Surg 17(3):141–143

  33. 33.

    Hirschmann MT, Konala P, Amsler F, Iranpour F, Friederich NF, Cobb JP (2011) The position and orientation of total knee replacement components: a comparison of conventional radiographs, transverse 2D-CT slices and 3D-CT reconstruction. J Bone Joint Surg Br 93(5):629–633.

  34. 34.

    Boonen B, Schotanus MGM, Kerens B, Hulsmans FJ, Tuinebreijer WE, Kort NP (2017) Patient-specific positioning guides for total knee arthroplasty: no significant difference between final component alignment and pre-operative digital plan except for tibial rotation. Knee Surg Sports Traumatol Arthrosc 25(9):2809–2817.

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Author information

PB conceived, designed, coordinated the study and drafted the manuscript. AB coordinated the study, collected data and drafted the manuscript. JM conceived the study and critically reviewed the manuscript. SK analyzed the data and drafted the manuscript. MS participated in the design of the study, analyzed the data and critically reviewed the manuscript. DJ participated in the design of the study, coordinated the study and critically reviewed the manuscript. All authors have read and approved the final manuscript.

Correspondence to P. Bollars.

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Conflict of interest

PB and JM are consultants on the NAVIO Robotic technique for Smith & Nephew, Europe. The other authors certify that they have no commercial associations (e.g., consultancies, stock ownership, equity interest, patent/licensing arrangements) that might pose a conflict of interest in connection with the submitted abstract.

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Ethical approval by the local ethical committee was obtained for this study.

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Informed consent was not necessary since it was a retrospective study.

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Bollars, P., Boeckxstaens, A., Mievis, J. et al. Preliminary experience with an image-free handheld robot for total knee arthroplasty: 77 cases compared with a matched control group. Eur J Orthop Surg Traumatol (2020).

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  • Total knee arthroplasty
  • Total knee replacement
  • Knee
  • Robot
  • Image-free handheld
  • Precision freehand sculpting system
  • Outliers
  • Alignment