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Letters to the Editor to:

Scientific Articles:
Young-Hoo Kim, Jun-Shik Kim, Yoowang Choi, and Oh-Ryong Kwon
Computer-Assisted Surgical Navigation Does Not Improve the Alignment and Orientation of the Components in Total Knee Arthroplasty
J Bone Joint Surg Am 2009; 91: 14-19 [Abstract] [Full text] [PDF]
*Letters to the Editor: Submit a response to this article

Electronic letters published:

[Read Letter to the Editor] Dr. Kim and colleagues respond to Drs. Ferretti and Conteduca
Young-Hoo Kim, MD, Jun-Shik Kim, MD; Yoowang Choi, MD; Oh-Ryong Kwon, MD   (29 April 2009)
[Read Letter to the Editor] Computer-Assisted Surgical Navigation Does Not Improve the Alignment and Orientation of the...
Andrea Ferretti, MD, Fabio Conteduca, MD   (29 April 2009)
[Read Letter to the Editor] Dr. Kim and colleagues respond to Dr. Matziolis and Mr. Perka
Young-Hoo Kim, MD, Jun-Shik Kim, MD; Yoowang Choi, MD and Oh-Ryong Kwon, MD   (1 April 2009)
[Read Letter to the Editor] Computer Assisted Surgical Navigation for Total Knee Arthroplasty
Georg Matziolis, Carsten Perka   (18 March 2009)

Dr. Kim and colleagues respond to Drs. Ferretti and Conteduca 29 April 2009
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Young-Hoo Kim, MD,
Professor
Ewha Womans University School of Medicine,
Jun-Shik Kim, MD; Yoowang Choi, MD; Oh-Ryong Kwon, MD

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Re: Dr. Kim and colleagues respond to Drs. Ferretti and Conteduca

younghookim{at}ewha.ac.kr Young-Hoo Kim, MD, et al.

Thank you for your interest in our recent article (1). You are correct in stating that since we did not navigate the rotational alignment of the tibial competent, the rotational deviation and the incidence of outliers of the tibial component between the two groups were similar.

Although there was a tendency to have a better alignment in both coronal and sagittal planes in the navigated group, these differences were not significant between the two groups (P > 0.05). Furthermore, we believe that these marginal differences are not clinically meaningful.

Therefore, we believe the title of the paper is appropriate and the conclusions are fully justified by the results.

Reference

1. Kim YH, Kim JS, Choi Y, Kwon OR. Computer-assisted surgical navigation does not improve the alignment and orientation of the components in total knee arthroplasty. J Bone Joint Surg Am. 2009;91:14-9.
Computer-Assisted Surgical Navigation Does Not Improve the Alignment and Orientation of the... 29 April 2009
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Andrea Ferretti, MD,
Chairman
Orthopaedic Department Sant'Andrea Uniuversity Hospital, Rome, Italy,
Fabio Conteduca, MD

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Re: Computer-Assisted Surgical Navigation Does Not Improve the Alignment and Orientation of the...

aferretti51{at}virgilio.it Andrea Ferretti, MD, et al.

To the Editor:

We congratulate Dr. Young-Hoo Kim and co-authors for studying this important topic (1), but we question whether their conclusions are actually supported by the data. After a careful reading of the paper, we have two concerns that we would like to share with the authors.

The first concern is about rotational alignment. The authors did not provide details about the ability of the system used in their study to actually navigate the rotation of the tibial implant. As the majority of the navigation systems currently in use do not allow navigation of the rotation of the tibial insert, the lack of difference in this parameter between standard and CAOS is not surprising.

The second, and more important concern, is about the reported results of coronal and sagittal alignment of the two groups. In analyzing all of the radiographic parameters, as shown in Table III, all the results in the CAOS group are much better when compared to the standard group, with a difference ranging from about 40% (outliers > 3° in tibial sagittal plane) to 100% (outliers > 3° in tibial coronal plane). Even if the differences are not statistically significant according to the statistical method used, the results seem to indicate a strong trend in favor of the CAOS, at least in the radiographic results and in the accuracy of the implant positioning.

Therefore, we believe the title of the paper is misleading and that the conclusions are too strong and not fully justified by the results.

The authors did not receive any outside funding or grants in support of their research for or preparation of this work. Neither they nor a member of their immediate families received payments or other benefits or a commitment or agreement to provide such benefits from a commercial entity. No commercial entity paid or directed, or agreed to pay or direct, any benefits to any research fund, foundation, division, center, clinical practice, or other charitable or nonprofit organization with which the authors, or a member of their immediate families, are affiliated or associated.

Reference

1. Kim YH, Kim JS, Choi Y, Kwon OR. Computer-assisted surgical navigation does not improve the alignment and orientation of the components in total knee arthroplasty. J Bone Joint Surg Am. 2009;91:14-9.
Dr. Kim and colleagues respond to Dr. Matziolis and Mr. Perka 1 April 2009
Previous Letter to the Editor Next Letter to the Editor Top
Young-Hoo Kim, MD,
Professor
Ewha Womans University School of Medicine, Seoul, South Korea,
Jun-Shik Kim, MD; Yoowang Choi, MD and Oh-Ryong Kwon, MD

Send letter to journal:
Re: Dr. Kim and colleagues respond to Dr. Matziolis and Mr. Perka

younghookim{at}ewha.ac.kr Young-Hoo Kim, MD, et al.

We thank Drs. Matziolis and Perka for their interest in our recent article(1). We acknowledge errors in our Table E-1 for the outliers in the sagittal (9 navigated vs 24 conventional) and the coronal plane (15 navigated vs 27 conventional). "9 of 160 knees (6%)" should be corrected to, "16 of 160 knees (10%)". Also, "27 of 160 knees (17%)" should be corrected to, "25 of 160 knees (16%)". We did not notice these errors when we submitted the manuscript or on the galley proofs.

The precision of the hip center may be different when comparing different navigation systems. Our previously published data (2) using the Vector Vision CT- free knee (Brain LAB, Munich, Germany) and another previous unpublished data using Ci Version CT-free knee (Brain LAB, Munich, Germany) revealed similar results to those of the current study.

References

1. Kim YH, Kim JS, Choi Y, Kwon OR. Computer-assisted surgical navigation does not improve the alignment and orientation of the components in total knee arthroplasty. J Bone Joint Surg Am. 2009;91:14-9.

2. Kim YH, Kim JS, Yoon SH. Alignment and orientation of the components in total knee replacement with and without navigation support: a prospective, randomised study. J Bone Joint Surg Br. 2007;89:471-6.
Computer Assisted Surgical Navigation for Total Knee Arthroplasty 18 March 2009
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Georg Matziolis,
Consultant Orthopaedic Surgeon
Orthopaedic Department, Center for Musculoskeletal Surgery, Charité - University Hospital Berlin,
Carsten Perka

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Re: Computer Assisted Surgical Navigation for Total Knee Arthroplasty

Georg.Matziolis{at}Charite.de Georg Matziolis, et al.

To the Editor:

I read with interest the paper by Kim et al. (1) in which the authors address the ongoing controversy about the role of navigation in total knee arthroplasty(TKA). Although the number of patients included in the study seems sufficient, I believe that their conclusion that the use of navigation does not result in more accurate implant positioning is not supported by their results.

The data presented in Table E-1 for the tibial outliers in the sagittal (9 navigated vs. 24 conventional) and the coronal plane (15 navigated vs. 27 conventional) show a significant difference in the X˛ test (p=0.006 for the coronal plane and p=0.047 for the sagittal plane). Although navigated as well as conventional tibial component positioning is based on extramedullary bone landmarks, the computer assistance significantly reduced outliers in both planes.

Regarding the femoral component, the precision with which the hip center is determined is crucial for determining the optimal femoral alignment. Finding the hip center depends on the mathematical algorithm used by each specific navigation system and differs between the systems and even different software versions of the same system. Therefore the conclusion about navigated femoral alignment precision should not be generalized to all navigation systems.

The authors did not receive any outside funding or grants in support of their research for or preparation of this work. Neither they nor a member of their immediate families received payments or other benefits or a commitment or agreement to provide such benefits from a commercial entity. No commercial entity paid or directed, or agreed to pay or direct, any benefits to any research fund, foundation, division, center, clinical practice, or other charitable or nonprofit organization with which the authors, or a member of their immediate families, are affiliated or associated.

Reference

1. Kim YH, Kim JS, Choi Y, Kwon OR. Computer-assisted surgical navigation does not improve the alignment and orientation of the components in total knee arthroplasty. J Bone Joint Surg Am. 2009;91:14-9.