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What should be considered in using standard knee radiographs to estimate mechanical alignment of the knee?
Osteoarthritis and Cartilage 18 (2010) 1545
Letter to the Editor
What should be considered in using standard knee radiographs to estimate mechanical alignment of the knee? Dr. Cooke and his colleagues correctly note that the relationship between anatomical axis and mechanical axis of the knee can vary as a result of many factors including ethnicity, gender, and, fundamentally, variations in bone geometry. We also agree with their view that deformity patterns in patients with knee osteoarthritis may vary by the ethnic origin, and varus deformity would be much more common in Asian individuals1. However, considering our finding that alignments in patients without osteoarthritis and male osteoarthritic subjects differ from those in female patients with severe osteoarthritis, we suspect that many unknown acquired factors are associated with deformity patterns2, which warrant future studies. In addition, we certainly would like to echo their concern over the validity of a standard 14 17 inches knee radiograph to estimate the mechanical axis of a whole limb. Nonetheless, the knee radiographs would remain to be a standard radiographic tool for practice or epidemiologic studies3,4 and are only the radiographic information available in major total knee arthroplasty (TKA) series in literatures5. Therefore, clinical values of the standard knee radiographs cannot be defied, and our study would provide valuable insights when estimating mechanical axis using standard knee radiographs. Once again, we are grateful to Dr. Cooke and his colleagues for their high appreciation of our study as well as their substantial contribution to the literature regarding this important issue. Author contributions Conception of the article: CB Chang, TK Kim; Drafting the article: CB Chang; Revising critical for important intellectual content: TK Kim. Conflict of interest The authors declare no conflict of interest.
Acknowledgements Grant support: none. References 1. Cho HJ, Chang CB, Yoo JH, Kim SJ, Kim TK. Gender differences in the correlation between symptom and radiographic severity in patients with knee osteoarthritis. Clin Orthop Relat Res 2010;468:1749–58. 2. Cooke TD, Harrison L, Khan B, Scudamore A, Chaudhary MA. Analysis of limb alignment in the pathogenesis of osteoarthritis: a comparison of Saudi Arabian and Canadian cases. Rheumatol Int 2002;22:160–4. 3. Janakiramanan N, Teichtahl AJ, Wluka AE, Ding C, Jones G, Davis SR, et al. Static knee alignment is associated with the risk of unicompartmental knee cartilage defects. J Orthop Res 2008;26:225–30. 4. Hunter DJ, Niu J, Felson DT, Harvey WF, Gross KD, McCree P, et al. Knee alignment does not predict incident osteoarthritis: the Framingham osteoarthritis study. Arthritis Rheum 2007;56:1212–8. 5. Ritter MA, Faris PM, Keating EM, Meding JB. Postoperative alignment of total knee replacement. Its effect on survival. Clin Orthop Relat Res 1994;299:153–6. C.B. Chang, T.K. Kim* Joint Reconstruction Center, Seoul National University Bundang Hospital, Seongnamsi, Republic of Korea * Address correspondence and reprint requests to: Tae Kyun Kim, Joint Reconstruction Center, Seoul National University Bundang Hospital, 300 Gumidong, Bundangu, Seongnamsi, Gyunggido (463–707), Republic of Korea. Fax: 82-31-787-4056. E-mail address: [email protected]
1063-4584/$ – see front matter Ó 2010 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.joca.2010.08.007
Letter to the Editor
What should be considered in using standard knee radiographs to estimate mechanical alignment of the knee? Dr. Cooke and his colleagues correctly note that the relationship between anatomical axis and mechanical axis of the knee can vary as a result of many factors including ethnicity, gender, and, fundamentally, variations in bone geometry. We also agree with their view that deformity patterns in patients with knee osteoarthritis may vary by the ethnic origin, and varus deformity would be much more common in Asian individuals1. However, considering our finding that alignments in patients without osteoarthritis and male osteoarthritic subjects differ from those in female patients with severe osteoarthritis, we suspect that many unknown acquired factors are associated with deformity patterns2, which warrant future studies. In addition, we certainly would like to echo their concern over the validity of a standard 14 17 inches knee radiograph to estimate the mechanical axis of a whole limb. Nonetheless, the knee radiographs would remain to be a standard radiographic tool for practice or epidemiologic studies3,4 and are only the radiographic information available in major total knee arthroplasty (TKA) series in literatures5. Therefore, clinical values of the standard knee radiographs cannot be defied, and our study would provide valuable insights when estimating mechanical axis using standard knee radiographs. Once again, we are grateful to Dr. Cooke and his colleagues for their high appreciation of our study as well as their substantial contribution to the literature regarding this important issue. Author contributions Conception of the article: CB Chang, TK Kim; Drafting the article: CB Chang; Revising critical for important intellectual content: TK Kim. Conflict of interest The authors declare no conflict of interest.
Acknowledgements Grant support: none. References 1. Cho HJ, Chang CB, Yoo JH, Kim SJ, Kim TK. Gender differences in the correlation between symptom and radiographic severity in patients with knee osteoarthritis. Clin Orthop Relat Res 2010;468:1749–58. 2. Cooke TD, Harrison L, Khan B, Scudamore A, Chaudhary MA. Analysis of limb alignment in the pathogenesis of osteoarthritis: a comparison of Saudi Arabian and Canadian cases. Rheumatol Int 2002;22:160–4. 3. Janakiramanan N, Teichtahl AJ, Wluka AE, Ding C, Jones G, Davis SR, et al. Static knee alignment is associated with the risk of unicompartmental knee cartilage defects. J Orthop Res 2008;26:225–30. 4. Hunter DJ, Niu J, Felson DT, Harvey WF, Gross KD, McCree P, et al. Knee alignment does not predict incident osteoarthritis: the Framingham osteoarthritis study. Arthritis Rheum 2007;56:1212–8. 5. Ritter MA, Faris PM, Keating EM, Meding JB. Postoperative alignment of total knee replacement. Its effect on survival. Clin Orthop Relat Res 1994;299:153–6. C.B. Chang, T.K. Kim* Joint Reconstruction Center, Seoul National University Bundang Hospital, Seongnamsi, Republic of Korea * Address correspondence and reprint requests to: Tae Kyun Kim, Joint Reconstruction Center, Seoul National University Bundang Hospital, 300 Gumidong, Bundangu, Seongnamsi, Gyunggido (463–707), Republic of Korea. Fax: 82-31-787-4056. E-mail address: [email protected]
1063-4584/$ – see front matter Ó 2010 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.joca.2010.08.007