Abstract
After a knee replacement procedure, postoperative radiological assessment is carried out to evaluate outcome and predict procedure success. For this assessment, long-standing load-bearing antero-posterior radiographs are used to carry out manual identification of anatomic landmarks. These landmarks are subsequently used to estimate leg alignment. The positions of the landmarks in the radiographs are affected by the patient pose and the X-ray projection center. Although there is some past work exploring the impact of patient pose on the landmarks in the radiographs, there is no previous work on the impact of the X-ray projection center on the estimated leg alignment. In this work, we carried out a study of the impact of patient foot rotation, and X-ray projection center on landmark measurement errors, and estimation of leg alignment. In this evaluation, landmarks were first identified in three-dimensional computed tomography scans. Digitally reconstructed radiographs were then obtained from these scans under varying rotation and projection centers. Subsequently, landmarks were manually identified in these radiographs and leg alignment was estimated from these landmarks. We found that foot rotation leads to increased errors in certain landmarks. We also found that variations in the X-ray projection center do not lead to significant (p<0.01) errors in landmark measurements. Also, errors as large as 13.1 mm for the femoral knee center and 13.6 mm for the lateral malleolus led to a maximum error of 1.46° for the femoral mechanical axis and 0.66° for the tibial mechanical axis.
References
[1] Akagi M, Asada S, Mori S, Matsushita T, Hashimoto K, Hamanishi C. Estimation of frontal alignment error of the extramedullary tibial guide on the bi-malleolar technique: a simulation study with magnetic resonance imaging. Knee 2012; 19: 836–842.10.1016/j.knee.2012.03.006Search in Google Scholar PubMed
[2] Choi WC, Lee S, An JH, Kim D, Seong SC, Lee MC. Plain radiograph fails to reflect the alignment and advantages of navigation in total knee arthroplasty. J Arthroplasty 2011; 26: 756–764.10.1016/j.arth.2010.07.020Search in Google Scholar PubMed
[3] Cobb JP, Dixon H, Dandachli W, Iranpour F. The anatomical tibial axis reliable rotational orientation in knee replacement. J Bone Joint Surg Br 2008; 90-B: 1032–1038.10.1302/0301-620X.90B8.19905Search in Google Scholar PubMed
[4] Cooke TD, Scudamore RA, Bryant JT, Sorbie C, Siu D, Fisher B. A quantitative approach to radiography of the lower limb. Principles and applications. J Bone Joint Surg Br 1991; 73: 715–720.10.1302/0301-620X.73B5.1894656Search in Google Scholar PubMed
[5] de Chaumont F, Dallongeville S, Chenouard N, et al. Icy: an open bioimage informatics platform for extended reproducible research. Nat Methods 2012; 9: 690–696.10.1038/nmeth.2075Search in Google Scholar PubMed
[6] Hunt MA, Fowler PJ, Birmingham TB, Jenkyn TR, Giffin JR. Foot rotational effects on radiographic measures of lower limb alignment. Can J Surg 2006; 49: 401–406.Search in Google Scholar
[7] Ibanez L, Schroeder W, Ng L, Cates J. The ITK software guide: the Insight Segmentation and Registration Toolkit. Clifton Park, N.Y.: Kitware Inc. 2003.Search in Google Scholar
[8] Lonner JH, Laird MT, Stuchin SA. Effect of rotation and knee flexion on radiographic alignment in total knee arthroplasties. Clin Orthop Relat Res 1996; 331: 102–106.10.1097/00003086-199610000-00014Search in Google Scholar PubMed
[9] Luo C-F. Reference axes for reconstruction of the knee. Knee 2004; 11: 251–257.10.1016/j.knee.2004.03.003Search in Google Scholar PubMed
[10] Prakash U, Wigderowitz CA, McGurty DW, Rowley DI. Computerised measurement of tibiofemoral alignment. J Bone Joint Surg Br 2001; 83: 819–824.10.1302/0301-620X.83B6.0830819Search in Google Scholar
[11] Radtke K, Becher C, Noll Y, Ostermeier S. Effect of limb rotation on radiographic alignment in total knee arthroplasties. Arch Orthop Trauma Surg 2010; 130: 451–457.10.1007/s00402-009-0999-1Search in Google Scholar PubMed
[12] Rauh MA, Boyle J, Mihalko WM, Phillips MJ, Bayers-Thering M, Krackow KA. Reliability of measuring long-standing lower extremity radiographs. Orthopedics 2007; 30: 299–303.10.3928/01477447-20070401-14Search in Google Scholar PubMed
[13] Schroeder W, Martin K, Lorensen B. Visualization Toolkit: an object-oriented approach to 3D graphics. 4th ed. Clifton Park, N.Y.: Kitware 2006.10.1016/B978-012387582-2/50003-4Search in Google Scholar
[14] Skyttä ET, Haapamäki V, Koivikko M, Huhtala H, Remes V. Reliability of the hip-to-ankle radiograph in determining the knee and implant alignment after total knee arthroplasty. Acta Orthop Belg 2011; 77: 329–335.Search in Google Scholar
[15] Swanson KE, Stocks GW, Warren PD, Hazel MR, Janssen HF. Does axial limb rotation affect the alignment measurements in deformed limbs? Clin Orthop Relat Res 2000; 371: 246–252.10.1097/00003086-200002000-00029Search in Google Scholar PubMed
[16] Yaffe MA, Koo SS, Stulberg SD. Radiographic and navigation measurements of TKA limb alignment do not correlate. Clin Orthop Relat Res 2008; 466: 2736–2744.10.1007/s11999-008-0427-9Search in Google Scholar PubMed PubMed Central
©2017 Walter de Gruyter GmbH, Berlin/Boston
