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Letter to the Editor

No Difference Between Trabecular Metal Cones and Femoral Head Allografts in Revision TKA

Minimum 5-year Followup

Chen, Zhuoyuan MD; Yang, Yang MD; Xiao, Tao PhD

Clinical Orthopaedics and Related Research®: May 2018 - Volume 476 - Issue 5 - p 1120
doi: 10.1007/s11999.0000000000000210
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Z. Chen Y. Yang, T. Xiao, Department of Orthopaedics, The Second Xiangya Hospital of Central South University, Changsha, China

T. Xiao PhD, The Second Xiangya Hospital of Central South University, 87 Xiangya Rd, Changsha 410011, China, Email: xiaotaoxyl@163.com

(RE: Sandiford NA, Misur P, Garbuz DS, Greidanus NV, Masri BA. No Difference Between Trabecular Metal Cones and Femoral Head Allografts in Revision TKA: Minimum 5-year Followup. Clin Orthop Relat Res. 2017;475:118-124).

The authors certify that neither they, nor any members of their immediate families, have any commercial associations (such as consultancies, stock ownership, equity interest, patent/licensing arrangements, etc.) that might pose a conflict of interest in connection with the submitted article.

All ICMJE Conflict of Interest Forms for authors and Clinical Orthopaedics and Related Research® editors and board members are on file with the publication and can be viewed on request.

The opinions expressed are those of the writers, and do not reflect the opinion or policy of CORR® or The Association of Bone and Joint Surgeons®.

Received November 26, 2017

Accepted January 17, 2018

To the Editor,

We read the article by Sandiford and colleagues [3] with great interest. Although this is a valuable study, we have some queries for the authors.

In the Patients and Methods section, the authors noted that 45 TKA revisions were performed using augmentation of host bone. Of those 45, surgeons used “femoral head allograft in 30 (75%) and trabecular metal cones in 15 (25%).” Shouldn’t the percentages be 66.7% and 33.3%, respectively?

In the Trabecular Metal Cone Technique section, the authors stated: “Nine Type 2A and two Type 2B femoral defects and 13 Type 2A and six Type 2B tibial defects were treated with femoral head allografts. Four Type 2B and two Type 3 femoral defects and two Type 2A and seven Type 2B tibial defects were treated using trabecular metal cones.” However, the second sentence does not match up with the data in Table 1. Are the data in the text or in Table 1 correct?

In the Conclusions section, the authors state that both techniques are viable options for the management of Anderson Orthopaedic Research Institute (AORI) Type 2 and 3 defects. But in the study, no patients with Type 3 bone defects were treated with femoral head allografts. Because of this, we believe that that the study’s conclusions may be overstated as published.

Finally, the authors used the Oxford Knee Score, WOMAC, SF-12, and the UCLA activity score to assess knee function and quality of life, and additionally, radiographs were assessed for signs of loosening. But radiostereometric analysis (RSA) is also important because the AORI classification referenced in the article is based on radiological images. In fact, in a study by Jensen and colleagues [2], the difference between the mean maximum total point motion of the trabecular metal cone group and the no trabecular metal cone group was almost 2 mm, but they could not detect this as a significant difference. However, in Sandiford and colleagues, perhaps there is a significant difference between the trabecular metal cone and femoral head allograft groups. If Sandiford and colleagues compared outcomes of the two groups’ images at 3 weeks, 6 weeks, 3 months, and 1 year using RSA [1], and then annually after 1 year, using the methods they used, perhaps their conclusions would have been more convincing.

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References

1. Brown NM, Bel JA, Jung EK, Sporer SM, Paprosky WG, Levine BR. The use of trabecular metal cones in complex primary and revision total knee arthroplasty. J Arthroplasty. 2015;30:90–93.
2. Jensen CL, Petersen MM, Schrøder HM, Flivik G, Lund B. Revision total knee arthroplasty with the use of trabecular metal cones: A randomized radiostereometric analysis with 2 years of follow-up. J Arthroplasty. 2012;27:1820–1826.
3. Sandiford NA, Misur P, Garbuz DS, Greidanus NV, Masri BA. No difference between trabecular metal cones and femoral head allografts in revision TKA: Minimum 5-year followup. Clin Orthop Relat Res. 2017;475:118–124.
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